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MG Midget and Sprite Technical - Lumpy Running with 97 RON - '73 Midget

Evening,


I have a 1973 midget III and have recently balanced the carbs after a full (spindles and all) re-furb. I then sorted the mixture and gave her an oil and plugs service.

She sat for a week and stared fine yesterday, took her up to BP as I was on 1/4 tank. Thought I might try some super and advance the ignition to make the most of it.

A few minute of running after I put the super unleaded in it started to run really lumpy and be very hesitant at low rpm/high load.

This morning I stared her again. Started fine but idled lumpy and with any increase of throttle would be running on 3 cylinders.

I checked the plugs, all were black and 1,2 and 3 were wet it was running so rich, interestingly 4 was dry.

Another observation was the behavior of my in-line fuel filter. Before the fuel level only ever sat at 1/4 up the fuel filter, but she ran fine. Now, with the 97RON fuel the fuel filter is full. Coincidence? or another hint?


Is this all down to the ignition timing needing changing due to the higher octane fuel? I am just shocked it made this much of a difference, from a smooth runner to un-drivable.


Any help much appreciated,

Sincerely,
- Richard
R L J Oakley

Has nothing to do with the higher octane fuel.
It is likely to be the carbs where something has not gone 100% right in the refurb.
Leave the ignition as it was and check the needle valves
Onno Könemann

As Onno, plus release choke and check jets are returning to fully 'up' position.

#4 was dry as it was the one that was managing to fire reasonably regularly.

A
Anthony Cutler

Choke was fine.

She was actually running on 2 cylinders... I checked the mix first with the lifting pins and it sounded fine. Pulled the HT leads off to see which were not working. Neither 1 or 2 was.

Checked the dizzy cap and rotor. Both still look brand new. Swapped the HT leads around to see if they were faulty, 1 and 2 still not firing.

Shoved the old plugs back in (replaced in December) and she started and ran fine.

The plugs were NGK coppers. Anyone else had two fail suddenly with only 50 miles usage?


Sincerely,
- Richard
R L J Oakley

Check carb float height. Float tips must be 1/8" to 3/16" from the bowl chamber top when the needle valve closes. Over the years, needle and seats have changed according to vendors and sources and so has the height. Usually, floats seem to end up sitting too high and the seats must be shimmed to achieve proper mixture. No amount of adjusting jet height will compensate if the floats are not properly set.
Glenn Mallory

Well done on finding the problem

The failure of a new part part is so annoying and common enough to be a suspect but not spark plugs I'd have thought

I've been replacing my plugs every 6 to 12 months on my present Midget as they are so cheap as NOS (altho' I might stop doing that as they had a 2 year unlimited mileage warranty when new)

Pro-mechanics or breakdown Bill will know better but I've never had any problems with spark plugs that I can remember in the over 30 years I've been driving

I've used a few NGK copper over the years but same as any other plugs I've used I've never had a problem

Last 3 years I've been using NOS Champion copper 'plus'
Nigel Atkins

Sad to say Nigel I have seen many new plugs fail

Usually of a famous name too (Not often NGK)

Ten or fifteen years ago it was Champs that could cause trouble when new, but I've seen Bosch and others do it

I used to carry old plugs in my van to give to folks whose new ones let them down

A good "old" plug could save the day for people going on their hols
Bill 1

There you go, Bill has a much wider experience

I expect my NOS Champion plugs will turn out to be from 10-15 years ago I'll hold on to the old one that come out a bit longer just in case
Nigel Atkins


I was very surprised the spark plugs had had it. Or had they? Was it just coincidence that they started firing when I replaced them with old...

I'll explain why I've got my doubts, and apologise for this introduction sounding like the start of a bad horror movie... Sorry.

I went on a long run today after resetting the mix and checking my plugs were nice and sandy.

First 20 minutes of the run was the usual Midget fun. It's been a lovely day here in Oxford so I went round the houses; Oakley, Brill, Dorton, Thame (if you're au fait with the area).

I found, under load at high rpm the engine would conk out, well, go back down to two cylinders again and of course die pretty soon after, along with some pops as the unburned fuel hit the exhaust. I got my assistant to fiddle with the leads and re-seat them, and she started back up on 4 cylinders sounding fine.

This happened 3 times and seemingly up hills when I had to grab third.


Does anyone else suspect the coil, or should I be looking elsewhere?

Thanks for the help so far. With the sun, it's a shame not to be having trouble free jaunts.


Sincerely,
- Richard
R L J Oakley

Hi Richard I have been using NGK for many many years and some of those were racing years.

In that time I have NEVER changed an NGK plug due to failure. So imagine my surprise when I read your post with 2?

Finding your fault ought not to be too difficult but easy said.

With your car being a 73 you will have an electrical rev counter fitted, when the engine begins misfiring does the rev counter remain fairly constant?

This tells you if the low tension circuit is working correctly. If the rev counter swings around wildly when the engine misfires then the problem is with the low tension side of the ignition.


After that, do you have a timing lamp? if so then fit it to the main coil leads and go for a run (with lamp inside car). The lamp should show a consistant spark. When the engine misfires check the lamp is flashing consistantly. If it does not flash consistantly then the problem is probably the coil. If the lamp stays flashing consistantly then fit it to one of the leads. Same again with a failure indicating a problem with the rotor arm/ cap/ leads
Best of luck but not convinced this is not a fuel problem :)
Robert (Bob) Midget Turbo

The tacho is consistent when misfiring.

You believe it could be a fueling problem? In what way? After a run the plugs are Sandy in color. If I turn off the engine straight after the 2 cylinder running, the plugs in cylinder 1 and 2 are wet with fuel.

As with my second post, when I pull the leads off 1 and 2 it makes no difference, the spark plug is definitely not firing, but, shown by the wet plugs, the cylinders are definitely getting fuel. Surely this screams ignition?

I'll pick up a timing lamp and try your test. New HT leads are on their way. What coil would you guys recommend? They seem so cheap I wouldn't mind replacing it just for piece of mind.


Thanks for the continued help.

- Richard
R L J Oakley

Hi Richard I feel for you but diagnosing problems over the network is not easy, wish I was there!

The coil? let me ask this if the coil was faulty why would it select plugs 1 and 2 not to fire?

The only item common to cylinders 1 and 2 is the front carb? Thats why I think it maybe uel related. Also a rich mixture for whatever reason could cause the symptoms described
Robert (Bob) Midget Turbo

I'm thinking along the same lines as Bob... that the problem was actually with the front carb, and not the plugs. Abnormal enrichment of either carb can be caused by the float valves not seating properly, which can lead to overfilling and an overly rich mixture. I've been there with my single ZS carb, and the symptoms were similar... but affected all four cylinders.

Best,

-:G:-
Gryf Ketcherside

I'll check the gaps again. When I check the plugs in 1 and 2 they were slightly whitey-sand, so if anything, heading towards lean.

As I say, I'll check. Does anyone know the correct gaps off the top of their heads?


- Richard

R L J Oakley

The correct plug gap is 25 thou but if the plugs were set at between 15 and 30 thou these symptoms would not occur.
Bob Turbo Midget England

As it seems to be heat related and going from weak to non combustable on the front carb it would point to a sticking piston. I think maybe you swapped the dashpots over or otherwise have an interference in the bellchamber which prevents the piston rising and falling when hot. Plug 4 keeps running becuase it's farthest from the balance tube.
F Pollock

Apologies, I was asking about float gaps.

A sticking dashpot damper? I'll have a look. What's the best test?

Get her hot and take the air filter off, then lift up the piston?

- Richard
R L J Oakley

Drop the jet from the front carb and clean it and the feeder tube out thoroughly. You could have a bit of crud stuck in the jet which is preventing the needle from dropping down fully, and generally intermittently upsetting the fuel flow to the cyls. 1 & 2. It could have been introduced when you filled up, maybe dislodged from the filter hence the apparent change in fuel level there too.

Guy
Guy Oneandahalf Sprites

The dashpots need to go back to their respective pistons since thsy are matched as an assembly. If you've inadvertently swapped them over the piston in one might get tight and cause this problem. So you'd need to take them off, clean them in thinners and do a timed drop test and get the best match. With the dashpots and pistons off and jet reassembled following a clean look at the height of the fuel in the jet (pump on) You should be able to see the fuel level in both carbs bobbing up and down about 2 - 3mm below the top of the jet. Once reassembled push both pistons right to the top of the dashpot and let go. They should both drop at the same rate and hit the bridge with a soft clunk.
F Pollock

Here you go... a master class in air piston matching from John Twist:

http://www.youtube.com/watch?v=IfU47Oqq9wA

I recalled seeing this some time ago, and found it with a quick search. For that matter, he's got a wealth of great videos there, covering pretty much all aspects of MG maintenance.

Cheers,

-:G:-
Gryf Ketcherside

I was very careful to refurb one SU at a time in order to ensure there was no mix up.

I shall check how smooth they operate in the morning.

I will then post here how they behave. I shall also try and get a video if I can think of a way to host it.


Sincerely,
- Richard
R L J Oakley

Richard,
I was suggesting in my earlier message that some dirt has got washed into the front jet when you filled up with petrol, and since you refurbished them. It seems to me to fit the symptoms.

Guy
Guy Oneandahalf Sprites

Update:

I cleaned out the jet. blew some petrol through it. I also emptied the filter out as there was quite a bit of crap had found its way into it.

I matched the dashpots and they were fine, number 2 carb needed a little more oil in the dashpot but that was it.

I then replaced the old spark plugs I had put in cyl 1 and 2 with the new ones that I initially thought had failed. I cleaned these plugs up before fitting them.

Turned the car over. Nothing. Gave it a while and a little rock on the starter and she fired up... on 2 cylinders.

Replaced the plugs in 1 and 2 with the old ones and she fired up fine first time.

I then replaced the coil as I had a new one to hand.


Went for a long test drive with some big hills. Everything was fine. So I don't know if I'm waiting for her to miss again or if I've solved it. The plug issue still baffles me.


Sincerely,
- Richard
R L J Oakley

Update II:

Continuing on from before. Went for a drive today, car has been behaving fine since.

A few minutes from home and she splutters down to 2 cylinders and dies. Starts again on two.

I get under the bonnet and check the chock is in situ and the pistons aren't sticking. No sign of either. Checked the pistons lift fine when cracking, indeed they did. Wait a while and attempt a re-start. Nothing. Lots of cranking.

I took out the plugs for to replace them and instead of being wet and black as I was expecting they were white. I had just checked the mix with the lifting pins before leaving the house. Spot on.

I used the fuel filter to check was was happening when getting my (cold and frustrated) assistant to crank. Nothing was coming through. Took it out and attempted to check for blockages in the filter and re-tried, it didn't fill up at all. So, fuel pump gone? Any sure fire tests/best replacements to buy?

Anyway, rang a friend and got a lift back home to collect my Volvo. Towed back. Fin.


Any ideas again, gratefully received...

Sincerely,
- Richard
R L J Oakley

Hi Richard

Contrary to the thoughts of others the NGK plugs are not the problem. They do not fail, you may damage one occasionally but that will be rare.

So getting back on track we are back to the fuel problem

The 73 Midget had an electric fuel pump, so the first thing to ask is, do you hear this ticking in normal use? Is it ticking when the engine Stops/misfires?
Robert (Bob) Midget Turbo

It was ticking in the garage this morning before fire up. Which took a few attempts this time. The car's rather loud with the LCB exhaust on so I wouldn't be able to tell either way in use.

It's not the loudest pump so couldn't hear it at the side of the road (traffic or not working, I don't know).

- Richard
R L J Oakley

You need to check if fuel is coming from the pump when the engine refuses to fire.
This can be done by checking for fuel flow at the inlet to the carbs (carefully) If the pump is working correctly fuel will spill everywhere when the pipe is removed so be ready to switch off the ignition quickly.

I am begining to think the pump is faulty. When you had the engine firing on only the rear 2 cylinders this could be because fuel was being scavenged by the rear carb. The flow passes that carb first.
Robert (Bob) Midget Turbo

Air vent in filler cap blocked perhaps? How far does it go before it starts to splutter?
Guy

It seems to be about 30 minutes of running before the bad times occur.

I checked the lines at the road side (emptied the filter and reattached, I would have been able to see fuel being pumped in it working) and nothing was coming through.

I have found this: http://www.merlinmotorsport.co.uk/p10861/SOLID-STATE-ELECTRIC-FUEL-PUMP-1.5-2.5-PSI/product_info.html

I shall remove and check over the current one. I have been made aware that one really doesn't need a powerful fuel pump, in fact a powerful one can be detrimental. Is this one too weedy?


- Richard
R L J Oakley

Hi mate that is the fuel pump I have always fitted to MGs when replacing the original. Great pump.

I can not say for sure that your existing pump is faulty without me checking it, but if you are convinced fuel is not coming through then I would change it.
Robert (Bob) Midget Turbo

Well if you get 30 minutes of running then it isn't going to be a blocked air vent. But it was worth the thought!
Guy

What seems to suggest that it isn't a mixture setting is that the fault apparently appeared quite suddenly on what previously had been a good-running engine. It suggests to me either a faulty component or a fuel blockage from stirred-up sediment in the fuel tank. Things like mixture settings may deteriorate steadily, but rarely suddenly alter unless something has broken.

Guy
Guy

The mixture was checked after the car had reached 'N'.

I also checked the plugs after the last jaunt. Sandy brown.


Thanks for the advice gentlemen. Great help as always. I'll test the pump again in the morning, if not, I'll by the Facet. I've heard they're noisy, I'll have to see if it's acceptable to me.



- Richard
R L J Oakley

Their noisy on start up (engine not running) and when very low on fuel.
When the engine is running you should not realy hear it.
Provided you mounted it on ruber blocks
Onno Könemann

If, when it falters, it isn't delivering fuel then it could also be a partial blockage in the pipework, or it could be drawing in air in the pipe between the tank and the pump. It could also be a poor / loose electrical connection to the pump.
If it is one of these faults then fitting a new fuel pump isn't going to cure it! I would check and clear the pipework first and check the wiring. If it is the pump, the usual problem is a build up of deposits on the little contacts under the end cap. These will often clean up with a needle file or emery.
Guy

What would be the best method to clear the pipework out?

I take the existing pump off and have a play.

Can anyone suggest the best jacking/support points for these midgets? The rear diff is screaming to be used, but I don't like the idea of jacking it on the threaded drain plug.


Regards,
- Richard
R L J Oakley

Do you have an airline? Blowing air back through the pipework into the tank should clear any blockage debris.

I just jack on the rear diff, but use a hard rubber block or a piece of wood as a buffer on top of the jack saddle. The best idea is a pad with a 1" diameter hole drilled in it that will locate around the drain plug. Then put axle stands either under the outer ends of the back axle, or on the mounting plates for the front ends of the rear springs.
Guy

I have a compressor yes. I assume one blows back from the feed pipe to the carbs, and remove the pipe from the pump (aiming it into a bucket or something). Then from the pre-pump pipes to the tank. Or should I just leave everything in situ and blow straight back into the tank?


Thanks for the help,
- Richard
R L J Oakley

Richard, I think I would do as you suggest, in two stages.. I suspect blowing compressed air through the pump itself could split the diaphragm.

I take it that you are getting no delivery from the fuel pipe feed to the carbs?
Does your pump make a ticking noise? If it is the standard pump and it doesn't tick at all then the pump or electrics is faulty. Standard pumps do stick. You know, I presume, about the trick of a sharp thump to the side of the pump to get it to start up again?
Guy

I hear about 3 or four clicks when I turn the key to coil. The clicking then stops. If I turn off and turn back to coil I don't hear any clicking again, although I sometimes do...

Lately (yesterday) this has forced enough fuel through to get the car temporarily started on 2 cylinders.

I'll get the pump off this week for a fiddle. I'll wait to buy the new pump until I work out if the current lines are 6 or 8mm, and if the existing pump is servicible.

75psi should clear the lines... Or crack them.



- Richard
R L J Oakley

Richard, a few clicks then silence is exactly what you would expect from a good pump. It clicks until the carbs are full, then stops. Once the car is running it will then start to click again depending on how fast you are using fuel. From your description l think your pump is ok.

If you disconnect the fuel line at the carbs and turn on the ignition it should tick rapidly and pump fuel. If it ticks just a few times and then stops, you have a fuel pipe or filter blockage between the pump and carbs.
Guy

It was not clicking when I removed the pipe. Even attatched it definitely doesn't pump through enough to fill up the float chambers.

I'll stick with the blast and clean plan. Mine kick it back into life.

Any suggestions for in-situ fuel tank cleaning?


- Richard
R L J Oakley

Unless you know you have a fuel tank problem l would leave it alone as you may just loosen up more crud. Unless you remove the tank it is impossible to swill out any loosened rubbish.
For starters, l would disconnect the delivery pipe at the pump and at the carbs and clear this length with the airline.
The pump definitely sounds normal to me.
Guy

Hi Richard,
I have been following your thread on this problem with a particular interest as throughout I have had some very similar symptoms. An intermittent misfire that developed after several miles of perfectly normal running. Apparently dropping first one, then two cylinders before packing up all together. Other similar symptoms were fairly whitish plugs making me think it was fuel supply related, but then wet on other occasions. Leaving the car for a while it would start and run again. Following and joining in your thread I thought might give me some clues!

Yesterday I found and cured the problem. It was the feed wire between coil and dizzy (in my case an MG Metro electronic) that was faulty. The wire had broken internally part way along inside the insulation. Externally it seemed perfectly normal, but inside the wire ends were making a make/ break contact giving rise to the intermittent fault. Even when testing the wire for continuity with a meter it appeared OK as the ends happened to be making contact. But in use, as the wire warmed up after a while the insulated covering became softer and allowed the ends inside to part company. It then either stopped completely, or allowed a spark to periodically jump the gap as the capacitance altered resulting in a hesitant misfire and on at least one occasion when it ran like a single cylinder Perkins diesel!

Not saying yours is the same problem, but it shows just how elusive the answer can be sometimes!

Good luck with your fault finding!

Guy
Guy

Guy,

Thank you.

I had the fuel pump off today, blasted the system through from feed line back and collected the fuel in a jerry to examine. A few little bits of crud, but nothing that could block a jet let alone a pipe.

I tested the pump again the battery, clicked on fine. I then took it apart so check for any ingrained crud. All seemed very clean, so I put it back together again.

The wiring seemed very messy and everything was filthy, so I re-made the connection ends and strapped it back up, flipped the car onto coil and... nothing.

By this point I was very wet and cold so am leaving it for another day. Will get the multimeter out to see if it's the live or ground side that's faulty.


I'll replaced the HT leads also.


Regards,
- Richard
R L J Oakley

Richard - fault finding - they say you should only replace / repair one thing at a time and then re-test. Otherwise when you do fix it you won't know which bit was the culprit!

Are you saying there is no power on the live feed to the pump when you switch on the ignition? Or that there is power but it doesn't make it tick? It won't tick when there is resistance to the flow on the delivery pipe, as when the carb bowls are full and the needle valves are therefore closed. Or if there is some other blockage. The only other reason would be a faulty pump, but I think that you mean that when tested off the car it ticks away perfectly.

My pump packed up once during a track day session at Croft, which was mightily annoying! It then proceeded to stop 24 times on the 76 mile journey home. Each time I had to get out and reach under the car to thump the pump back into life with my fist.

Guy
Guy

The live feed was fine. The pumped worked off the car while being tested on a battery. I re-re-assembled the pump and hooked it back up. It worked this time, clicking away nicely.

The car started... On two cylinders. I replaced the (aforementioned 'faulty') plugs with two known working ones and she started on four.

Great, I thought I'd cracked it. I replaced all five HT leads. Started and heated up fine.

I went for a drive last night, a little misfire under heavy load that cleared itself after 10 minutes of running.

I then started to notice the fuel gauge, it was on empty. I had just brimmed it. My initial thought was that a line had come off or had a leak. I let off and pulled over, and as I let off the needle came back to full. I applied the throttle again and it slowly reduced to empty, pulled over and the needle rose back to full.

I checked the pump, all seemed fine, expect there was no clicking from it on coil.

I drove off again and the needle wasn't pratting about anymore.

5 minutes later she was down on two. I performed the usual checks, and still the pump was not clicking, I was aware it wouldn't if it felt there was enough pressure.

Eventually she would only crank with no attempt to fire. I checked the plugs on the block, all were working.

I was parked on a slight hill facing up, so I turned the car around (manually) and blew through the filler aperture and restarted. She was back on 4. Ran for 15 seconds, then down to two then 10 seconds later died.

Surely this is fuel pump?!


- Richard
R L J Oakley

I think it's time to drain the tank and fish out whatever is causing the blockage. It's a shame the tank is full because you'll need several washing up bowls to catch it all. But if you decide to drop the tank you can also check the sender wire and earth are OK.
F Pollock

Richard,
I am not surprised that you are getting frustrated by this - it's very bizarre!
Maybe the fuel gauge behaviour is related to the pump problem and is the clue.
I think that on a '73 car the feed that goes from ignition switch to the pump, also supplies fuse 5/6 which supplies the fuel gauge, indicators and the brake light switch.

So possibly the erratic fuel gauge is related to a fault on that circuit, also leaking power from the fuel pump supply. Perhaps the ignition switch contacts are faulty so that you are getting an intermittent power supply. Maybe the brake lights are shorting to earth when in use and cutting out the pump and gauge? You could temporarily remove that fuse (2nd down from the top, I think) and try it again. Without the fuse you should still have a working pump but no brake lights, fuel gauge, or indicators so a careful drive on quiet roads might be the best test.

I'm running out of guesses!

Guy
Guy

Hi Richard I will again try and help you mate.

It is almost obvious that this problem is fuel as many of us have discussed. I accept the efforts of Guy in particular to try and ensure the pump is faulty before condemning it completely but you need to move on.

If you can not be 100% sure the pump is not faulty then you either have to pay someone to confirm it or use that money to buy the new pump! Even if the pump is found not to be the problem you have not wasted your cash as you will have fitted a far better pump and will have avoided a problem in the next year or 2!

However it ought not to be too hard to determine a Midget pump issue.

First jack up the rear of the car to see he pump above the axle. Remove the flexi hose from the pump that goes to the tank. Blow down this pipe into the tank. This should be clear and you should feel the tank "bubbling" this will be the air you are blowing bubbling in the tank. If it oes not bubble then the pipe is broken in the tank or you have run out of fuel

Second connect the pump back up and remove the pipe feeding the carburettors. Place in a large tin (gallon can) start pump by turning the ignition to on the pump should pump fuel and fill the tank in 5 or so minutes. You should also do this test when the car stops on the road.

I only have one concern and that is the acion of the fuel gauge. Only 2 things can make that occur either the level is reduced in the tank? or the voltage to the gauge is reducing drastically. This is the same voltage potentially that is feeding the coil and if correct would cause the issues you are having.

However the very first thing to do is PROVE the fuel pump is NOT the problem
Robert (Bob) Midget Turbo

I'm very concious of Bob's (?) previous advice of not changing components for the sake of it and what he's just put but if you have the old type of fuel pump swapping it to an electronic will probably come up some time in the future or even now

As always I must say I've very little idea of mechanics and electric but I do have experience of annoying and difficult to pin down problems (if I can remember the solutions that is)

Some I'm sure think I've made up or mistaken the solutions sometimes

Certainly I'd follow the advice given by Bob but also go along with Guy on the electrics front

Full disconnect the battery before any electric work of course

Clean up and test as many connections including ignition switch wires and connectors as you can starting with the fuse box, you could try replacing the fuse Guy's on about as well as cleaning its connectors 5-6 (replacing the fuse that should get derision from some)

If that don't work I'd take the fuse box out and check it and clean it front and back noting all connections and which way it's fitted (it can get fitted in wrong orientation so the links on the back of the box are on the wrong wires)

Sometimes it's the things you can't see - recently a chap had a coil HT lead that only went faulty when warm (broken inside), I've had bulbs with intermitent filiment connections, when hot they disconnected and once cool again they'd reconnect until hot again - tested on a meter (when cold) before, during and after it
Nigel Atkins

I very rarely change something that is not proved faulty as you suggest Nige however here is a situation where for one reason or another Richard can not determine if the pump is faulty or not. His only option appears to be to find someone who can determine if the pump is faulty , which may cost him or change the pump

I am sure Richard will not mind me stating that sometimes people with limited ability will have to change things simply to eliminate that item unfortunate as that may be.
I also stated that on this occasion the money would not be wasted as changing an old SU pump is always a good thing IMO
Robert (Bob) Midget Turbo

Bob - As I understand it Richard has already cleared the fuel lines - blowing through them. He has also tested the pump off the car.

My suspicion was that the pump was suffering from the common Lucas problem of seeming to work but then intermittently sticking. That's why I mentioned mine stop-starting 24 times in 76 miles! If it is this fault with the pump, then when the fault does occur a sharp thump on the side of the fuel pump will get it ticking again, and at the same time confirm that a new pump is what is needed.

However the issue about the falling fuel gauge would to me indicate a fault with that supply. And as the same supply feeds the pump this would be well worth following up before spending money on a replacement after-market pump that may not be necessary in which case it wouldn't fix the problem! I doubt it would actually be the fuse as the supply to the pump is taken off "upstream" of the fuse box. But removing the fuse would take the other potential components out of the equation.

It seems to me it could be an erratic contact on the ignition switch which would have the combined effects of no fuel pumping, falling fuel gauge reading and coil misfire.

If it were my car I would remove that fuse and go for a drive. If the car stops I would get out and reach under to thump the pump a couple of times. If this restarts it then it shows that it needs a new pump (as you have already tried cleaning the contacts) If the pump doesn't restart when thumped then I would wiggle the ignition switch and wires from it in case the problem is there.
Guy

Bob, sorry I couldn't resist (you went hook, line and sinker, whatever a sinker is) and I agree sometimes it's more economically to change something that investigate or put up with it being faulty and being myself a less compotent I'm also agreeing with changing stuff once you've run out of your competence zone

Also if you're a less compotent like myself you are less likely to find or notice other stuff that would be obvious to more compotent others like POs' mistakes

Personally I'm not prepared to put up with intermitent problems and wouls sooner replace stuff that is, might be or will be faulty

I replaced my fuel pump on this Midget soon after getting the car as the one fitted was the old type and looked old altho' it worked, anyone could have had that old pump for free it may have worked well for years to come but I wasn't trusting it I'm too old, fat and impatient to crawl under cars to tap fuel pumps now

Guy, fuse was for fuel gauge plus who knows what else is going on when the problem happens that you can't see from the drivers seat - some PO wiring and fittings could throw up funny effects
Nigel Atkins

the end words went missing (did I type them ??) on a previous bit of mine -

>>I've had bulbs with intermitent filiment connections, when hot they disconnected and once cool again they'd reconnect until hot again - tested on a meter (when cold) before, during and after it<< the bulb would show as not faulty
Nigel Atkins


Thanks for all this help gentlemen.

I have indeed cleaned the lines out, and after first re-assembly the pump worked (I could hear it) and shot fuel through to the carbs, my transparent inline fuel filer is a useful window for this.

The pump was not working this morning, no clicking no fuel. I can try and clean out the lines again, but I can't see it making any difference.

I'll try and play with the fuses and get the multimeter on the ignition wires.

Although I'll try and not be offended by being labeled as having limited ability, I can use some of it to operate a multimeter.

With the new light of tomorrow, I'll see if, not I know the pump isn't clicking, it's still getting it's 12V feed. If it is, then I'm just buying a new Facet pump, I'm not going to cry over £35 as, as people have mentioned, I'm sure to have to replace it anyway in the future, I also think the SU diaphragm pump is a bad design. I'm certain the cost of a new pump is far less than the time someone will take to tell me "yer guv, looks like ya need a new fuel pump..."

If there is no feed, I'll get jiggling with the ignition barrel.



Thanks again all, more to follow tomorrow. I will fix her. I'm remaining British.


- Richard

R L J Oakley

If you can use a multimeter then you're well ahead of me I can only use a simple yes/no meter type thing

I'm a pessimist who's usually unlucky (is it self perpetuating?)

Bearing that in mind I'd still say, be aware:

intermittent problem could still possibly beat a multimeter reading

push or pull fuel pump

I managed to get a Facet fuel pump on my Rover P6 the type of which was always reliable and worked well but of course mine just didn't

If you fit a good electronic one in the original position with good clean electric supply and connections and fuel supply pipes and protect them with whatever they will give many years and tens of thousands of miles of trouble free service so the exposed and difficult to access location doesn't matter they look like the old pumps and give the same sort or clicking when fuelling noises - but they cost a lot more than £35 (or £22)

New shape Facet seem to start at £22 ! but if you’re fitting at the front of the car you may need to fit the two exhaust bobbins and bridging earth lead latter if like me you find that the Facet pump vibrates VERY noisily at tick over (unless that was just the old shape of pump or mine was excessively noisy)

Good luck, it might turn out to be just one bad electric connection somewhere (if you're lucky :) )
Nigel Atkins

I got - MG Midget Electric fuel pump
Suitable all Chrome bumper models AUF214Z £49.95 (£36 when I bought 3 years ago so shop around)

It looked very much like a Q&H item but I cant remember if it was boxed and marked as such but I've had no trouble with it or simular pumps fitted to my previous cars over many miles
Nigel Atkins

Afternoon,

I'm sure enough of you know the situation thus far, so I'll just plough on with an update.

New Facet pump arrived and I got down to Maplin to re-do the connections down there.

I went and bought some more fuel line and another small filter to protect this pump.

Drilled, mounted, fresh connections, 12V feed? Affirmative. Thrice checked the area. Turned on to coil and the pump clicked around 5 times and stopped. I thought this would be it stopping from there being enough pressure, car didn't start, there was no fuel going into the carb bowls.

I pressurised the tank and got some fuel through, By this point the battery was waning so I hooked the battery up to my 850 with some leads.

Turned over again, life... 2 cylinder life. Eventually dies again, must have been running on the fuel I got into the float manually.

I'm back at square 1.

To recap what's new:
Plugs
Leads
Coil
Cap (nearly)
Rotor (nearly)
Fuel pump
Lines


Ok... Next port of call?

Sincerely,
- Richard
R L J Oakley

Did you try a wiggle test on the ignition barrel wiring?
Did you resolve the issue of the fuel gauge dropping?(loosing its power supply)It does sound like your feed to the pump is intermittent. Either that or it isn't fuel related after all!
Guy

Well, I checked the pump supply again, still getting 12V even thought it's not clicking at all.

I wiggles and re sat every wire I could get to. Nothing. I remove the 2nd fuse down and re-tried. Nothing.


- Richard
R L J Oakley

Richard,
I am not familiar with Facet pumps. But I presume that, like the original Lucas ones they only stop clicking when either there is no power to them, or when the resistance to the flow of fuel is to great. The latter occurs when the carb float chambers are full, or possibly if there were a blockage in the fuel lines. You cleared the lines didn't you - both upstream to the tank and downstream to the carbs?

I am still not sure why you think the carbs are not filling properly. How have you determined this?

Guy
Guy

Blow throug all the hard lines and replace all the flex lines.
Flex lines can degrade and blok internaly and still look fine on the outside.
Blowing through with an airline will not work as it creates enough pressure to get through where a fuelpump won't.

Then pull off the fuel hose at the carb put in a bucket and turn on the ignition.
Then you know if the pump works
Onno Könemann

"I pressurised the tank and got some fuel through,"

If you have to pressurise the fueltank I would guess something is blocking the fuels way out of the tank.
Dirt?
Blocked airvent in the fuelcap causing a vacume in the tank?

Hook off the fuelpipe from the tank and put it in a sparecan filled with fuel then try to start the car again.
make sure air can get in the fueltank.
This way you can eliminate the fueltank for being "faulty" or not.

Im not a mechanic like some of the guys here so I have to simply go step by step and eliminate possible causes and hopefully get to the problem. :)
Arie de Best

Hi Richard

The Facet pumps pump vigorously all the time, if yours is not then either power is not at the pump or it is faulty.

Remove the pump and connect it directly across your battery. Does it pump?

If you want you problem solving please do this and start working in a logical manner. This is the very first step!
Bob Turbo Midget England

Hi Richard

You said in the original post, that you had an in-line filter. Have you tried taking that out of the system, just to rule it out?

Keith
Keith Nelson

All flexi lines are new. I shall take the pipes off and try the pump. I am 99.95% sure it will not pump.

For all the starts I had the fuel filler cap off just in case.

I shall whip it off and test it on a battery tomorrow.


Tediously,
Richard
R L J Oakley

Have you definitely confirmed that the float chambers are not filling properly? We are focussing on the pump - or at least on the fuel delivery side, but if the float chambers are full, then the pump won't pump anyway. Check that the carbs are both full and the floats and needle valves aren't stuck. It does sound like a problem with the front carb fuel delivery.

Your fuel filter doesn't incorporate a one-way valve does it? And it isn't installed the wrong way round ? - there is usually an arrow on the side somewhere to show the direction of fuel flow. Actually, I never use a fuel filter - I really don't think it necessary in this country - assuming your tank is in decent condition and not rusted inside I would chuck the fuel filter away.
Guy

"I would chuck the fuel filter away. "


Thats shocking to hear from an eco-friendly man like you Guy.
Dot chuck it away but dispose it in the by the counsil appointed special oilwasteproducts places/bins.

Save the world and think green.

actualy im thinking green as we speak...
Brittisch racing green ... on four wheels ... going for a drive without purpose or destination ... just burning fuell ...
LOL!!
Arie de Best

"All flexi lines are new"

Even the ones from the over flow of the float?
Onno Könemann

Sorry to be a pain but the pump would tick regardless of whether or not the lines were blocked. As would the SU pump albeit at a very low frequency.
Thus either the pump is stuffed or the power is not there. which could include a poor earth on the pump!

If the pump functions when connected to the battery then the issue will be with the wiring to the pump.

If it were a case that the pump stopped when the lines were blocked (which I am sure is not the case) then simply disconnecting the fuel lines would release the pump to operate.
Robert (Bob) Midget Turbo

Your problem seem to be heat related, this tread is interesting and long maybe I missed it. Do you use a nearly new black or a red rotor?

Flip
Flip Brühl 948 frog 59

Update.

Tested the pump without any lines on it at all. Nothing.

Got the multimeter out, 11.9V.

Took the pump off and tested straight on a battery. Worked fine.

Refitted and tried grounding the -ve directly to the battery to make sure it wasn't a ground issue. Nothing.

Sat in the car annoyed and the pump started clicking away. I took the opportunity to hook up the fuel lines again and let the pump pump through some fuel. It did it's job fine and the car started first click. Grand.

Ran for a few minutes and dies. Fuel pump not clicking.


So, electrical gremlins. I've tried the fuse trick to no avail. Why is the pump getting a 12v feed when it's not working, even though the pump works. Surely if it's a faulty wire somewhere, the 12v feed wouldn't be live.

It's getting to the point that I want to call an electrical engineer, but that would end up costing more than the car.


- Richard
R L J Oakley

Fantastic Richard now we are cooking so one step at a time
11.9 volts is not a good reading, it suggests a poor connection somewhere and is probably the reason why the pump only works occassionally.

I think the pump is fed from the ignition switch on a white wire. This particular white wire is connected into a push connector that is behind the trim panel next to the drivers knee.

I think it is worth a shot removing the trim panel and finding this white wire connection and cleaning it and making sure it is spot on. This same feed by the way powers the fuse box which in turn powers the fuel gauge. As you are aware your fuel gauge was loosing power also a little the other day.

Alternatively power the pump from a seperate supply and go and enjoy a drive.
Robert (Bob) Midget Turbo

I assumed 11.9 was a healthy reading? Am I looking for 14v? I thought that would only be while cranking.

I'll whip the trim off and see what's what. The whole area behind the dash is like a birds nest.

- Richard
R L J Oakley

Richard,
11.9 is in itself not that low, but just low enough to suggest a possible wiring fault or loose connection which may at times worsen and cause the pump to falter. You may recall I mentioned earlier a fault I found on mine which was an ignition LV wire that had broken inside the insulation. When cold it connected fine, but as it warmed with the current flowing the insulation softened alowing the wire to sag and braek its connection. If you have an intermitten feed to the pump, then this is the sort of fault to look for - most likely at one of the connectors as Bob describes.

As you discovered much earlier, the fuel gauge dropping down was another clue and is fed by the same supply so it looks like you are gradually narrowing down the fault location. I still believe it may be the ignition switch, or the wire between the switch and the connector that Bob describes and which feeds off to both the pump and the fuse box. This would result in your dual faults at both gauge and pump.

Guy

Guy

11.9 is a voltage you expect from a car that has been standing for a while or has had the electrics work with out charging the batery.

a complete healthy charged batery should deliver above 12V

running car should give above 13V

Run a + wire to the pump direct from the batery (smal switch in between)make thick enough.
If that works reconect the loom and start working back from the pump to the batery.
Each time you clean a contact or replace a piece of wire start the car and test it.
Onno Könemann

There's one thick loom running back from the ignition barrel to the rear arch where it splits into rear lights and fuel pump wires.

I've just bought more thick wire and I'm just going to re-wire the connection to the pump. I have the seat out and all the side trim off. It just seems easier to re-wire with nice fresh connections.

I'll be getting on with that in tomorrows light.

Moment of truth coming...

- Richard
R L J Oakley

Richard I think Bob is right to save confusion you should follow one person's advice one step at a time

I've resisted posting but I will add a couple of general comments here (please bear with me)

It's very difficult to do a wiggle and meter test fully without a second person - you can't be in two places at once

Guy has a very good piont about intermitently broken wires

(please don't take offence) you may need to recheck items/connections you've already checked

on a tricky problem always best to start at one end and carefully work your way back (or forward) Sod's Law you'll usually start the opposite end to the problems but at least your checking and cleaning as you go along is helping to prevent future problems

I think you putting >>The whole area behind the dash is like a birds nest<< may (only possibly) point to the problem Spridgets don't have many wires so don't get too messy - unless previous owners have been adding items in (I thought you might find a hidden fuel pump isolating switch with poor connections or possibly some other wires/connections coming off the original wires)

Good thing about simple cars like Spridgets (well UK models at least) is that if the engine doesn't run or runs badly it's usually only either electrics or fuel

With everything else going on I hope you remembered, before or after charging, to check the water levels in your battery too as you've already found a good fully charged battery is extremly handy to have (oh dear, I'm going to get slagged for this last paragraph -"patronising")
Nigel Atkins

I wired up the pump separately. Started via a switch on the dash. Works fine and car started.

Further electrical issues still haunt, namely the gauge sender. It was reading full, even when the ignition was off. I wiggled the wired into the tank under the car and it died to empty, another wiggle and it rises to full.

Also, when reversing into the garage my reverse lights stayed on when i was out of the car. I hit the switch a few times under the tranny tunnel carpet and it sorted it...

I don't know who's been wiring this car, but they certainly haven't done a great job.

Also, on my test drive I stopped off in the supermarket only to find my handbrake not attached. I'll have a look at the linkage tomorrow. Annoying.

Finally, just found AutoWindscreens have gone under and I had my Volvo booked in for Wednesday. Good week.


- Richard
R L J Oakley

Sorry but there's your problem - >>I don't know who's been wiring this car, but they certainly haven't done a great job<<

So a strict forward to back, step by step, methodical appraoch is required to find, resolve and repair each fault as potentially each many be linked to another

Check, clean and redo as required all connections, terminals and wires as you go along start at one end and go all the way to the other

This is why you'll need a good quality, well charged battery with good clean terminals and connections and the same for the fuses and fusebox - start with these and it'll made working on the electrical faults eaier to do

Don't forget to deal with all earthing connections too

Deal with one thing at a time and do seperate threads on them - you have a temp/permaneant solution to the pump problem so I'd suggest you start a new thread to check the fuel guage (onced you've thoroughly checked and cleaned battery and fusebox as above)

Don't rush anything put Radio 3 or 4
Nigel Atkins

This thread was discussed between 17/01/2011 and 14/02/2011

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