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MG Midget and Sprite Technical - Fuel Pump on 1275

Hello,

is the fuel pump on the 1275 serviceable.
reason - On start up this morning it went ok at first then started dying on me,had a look around all the usual places but then found fuel pouring out from underneath,on closer inspection it was coming from the top of the fuel pump (the end where the lines push on and the "O"ring is) When we took it off it came apart quite easily.Anyway was wondering is it serviceable or once it has gone like this i need to buy a new one and if so which one is best to get.

Thanks for looking Wayne.
W Williams

Not sure what you mean by "came apart quite easily".

Is it a standard SU pump?

If you have a Haynes manual, there is plenty of useful info in there.

While this BBS is a great source of information, it is no substitute for a (half)decent workshop manual.
Dave O'Neill 2

Cheers Dave,

yes i have a Haynes manual and when i say came apart i mean when i undid the clamp then the top of the pump came off


W Williams

Hi Wayne

Yes, that's definitely in two halves.

It isn't an original SU pump, probably a Moprod or similar aftermarket. I was a bit surprised when you said it came apart, because they are normally held together with 6 screws and don't come apart without a fight.

I would be tempted to replace it with a standard SU pump from any of the usual MG specaialists.
Dave O'Neill 2

This is what a standard pump looks like...


Dave O'Neill 2

Is it for sale.
W Williams

go electronic for fuel pump

don't spend money on cosmetics like wheels until you've . . . well you know what I advise

perfect example here

Wayne I could be well wrong, and often am, but if I had your car, or most others, I'd concentrate on regular servicing, maintanance and driving it
Nigel Atkins

Cheers Nigel,

Driving it shown this up.
W Williams

Which elctronic fuel pump do you mean Nigel and where from.

Cheers Wayne.
W Williams

Sorry Wayne, it's long gone. I just found the photo on my PC.
Dave O'Neill 2

Wayne - SU makes an all electronic pump. There are also the after market pumps, Facet, Fuel Flow ECCO, Carter, Airtex, all of which are electronic. Cheers - Dave
David DuBois

I bought this to replace my faulty SU pump

http://cgi.ebay.co.uk/FACET-POSI-FLOW-FUEL-PUMP-1-5-4-0-Psi-UNIONS-/370379988001?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item563c5e1c21

Your replacement pump needs to deliver 1.5 to 4 psi.

Facet pumps are recommended by others in the archives on this bbs as being good value & reliable... Mine has done about 400 miles with no problems.

The facet required different mounting points to the SU that it replaced & I had to replace the flexible pipes, partly due to age & part to make fitting to the new pump easier.

Alan.
Alan cotterill

Good point, Alan, that has not been made clear to him yet, and it is something that can easily be missed: make sure that whatever pump you buy, that it delivers no more than 3 or 4psi.

More than that will require an additional pressure regulator (and MOST fuel pumps will deliver too much more than that), which is one more piece of hardware in the fuel line that can fail, and the whole point of buying an electronic fuel pump is to get away from things that can go bad.

If you stay below that, then you're fine. Some folks find the constant noise of a Facet annoying, some mount them onto rubber blocks to reduce the noise. Others use SU pumps that are made today with solid state "points" (making them as dependable as any other kind of pump). Others simply use whatever is the very cheapest (the little, "no-name" cube pumps sold at all auto parts stores).

Norm
Norm Kerr

Wayne, the SU electronic is for keeping original appearance but if you're not worried about that hidden under the car then -

I put a Q&H electronic one on about 3 and a half years ago, no problems, plenty of mileage on it too

it fits to original bracket, hoses and location and no need for vent

inlet and outlet may loop the other way round (I can't remember) mark up anyway for easy future reference

renew electric connetions and protect them as the pump lives in a dirty place

renew hoses if required

then it'll be a fit and forget

one like this (free P&P on this one) - http://cgi.ebay.co.uk/MG-midget-Electric-Electronic-Replacement-Fuel-Pump-/150524394504?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item230bf3fc08

note this may be on sale elsewhere at a lower price, I've not looked and there may be better pumps but I'm happy with it
Nigel Atkins

try these guys http://www.fuelflow.co.nz
I recently installed one and it is great. The Facet had too much pressure and caused rich running.
Warren

Wayne,
I would go for a facet rather than an electonic 'SU' type of pump. The electronic 'SU' that I fitted (from MGOC) could not supply the engine with fuel at full throttle for more than a few seconds. The engine is only very mildly tuned - about 75BHP.
Don't forget that you will need a fuel pressure regulator with a facet, your carbs will flood without one (I am assuming you still have SU carbs).
Dave
D Brown

Dave B. You could have provided an answer to the problem I have experienced on a couple of occasions. Full thottle in third up a long steep hill and after about 15 seconds the engine started to flutter and die. I backed out of the thottle and it came good again. It's happened more than once, but always goes OK if I back off. I figured that it could be a fuel supply problem, but dismissed it, as the electronic S.U. type pump was new. I got it off Ebay and it works great under most conditions, but when asked to deliver lots of fuel for more than a few seconds, it fails. I've also noticed that after a long run, when I stop, it's rather noisy, sounding like it's struggling to keep up. So I think I may take your advice and go for a Facet.
Thanks
Bernie.
b higginson

before you do bernie, check that any of the fuel pipes are not squashed flat....
Rob Armstrong

there isn't any reason why a good SU pump would struggle to keep up with the carbs. Why not repair whatever is wrong with your particular unit, rather than throwing it away for a whole 'nother kind of pump?

Just curious,
Norm

Norm Kerr

Norm it's not an SU pump that's fell apart, have a look at Wayne's photo

I had a cube Facet on my P6 it was like a jack hammer, swaped it for a cylinder

the Q&H I've put on my present will get you up steep hills and mountains at very repectable speeds - of course subject to your car being . . . well you know the rest
Nigel Atkins

Bernie - Check your fuel system for an air leak. That would certainly cause the problem you are experiencing. Norm is correct, the SU pump, points or electronic is capable of supplying all the fuel that is needed for a Midget.

You can check this by removing the fuel line from the carbs and route it to the bottom of a glass jar, turn the ignition on and watch the stream of fuel going into the jar. If the stream is full of bubbles, then there is an air leak. Remove the line from the tank to the pump (loosen or remove the line from the fuel tank first to remove stop any fuel from siphoning out of the tank) and replace it with a flexible line that can be dipped into a can of fuel. Once again turn on the ignition and observe the flow of fuel into the jar, watching for bubbles. If no bubbles occur with this set up, then the air leak is in the line to the tank or the pickup tube in the tank. If there is still bubbles in the outlet stream, then the pump has an air leak in it, quite possibly a cracked turret on the inlet side of the pump. Cheers - Dave
David DuBois

My fuel system was in very good condition (new tank and flexible hoses, no kinks in the metal hoses) and my car serviced, carbs rebuild and tuned correctly and the engine was new as was the QH electronic fuel pump.
On the rolling road I saw the pressure gauge fall to zero after a few seconds at full throttle. The Rolling road man, Peter Baldwin, said this was common on mildly tuned a series engines (He tunes a lot of minis). Swapping for a facet has cured the problem.
It may not be every electonic SU, but mine certainly had this issue.
Dave
D Brown

I actually think that we may be a bit unfair to the standard SU on here! I 'serviced' mine a couple of years ago, new points, diaphragm etc. and it's been totally reliable ever since. As a precaution, I have a spare new SU in the boot (bargain from Beuilieu). Facets have been known to fail! In my experience, the SU is most likely to require a 'kiss' from a mallet to start the points if the cars been sat un used for a long time and the points have corroded.

The rythmic tick of the SU is all part of the midget experience and should be appreciated. Of course you can fit a near silent electric one, at the same time, stick in a 16 valve k series engine, get fuel injection, do away with the awful draughty body and get a tin top, in fact, why not upgrade for total reliablity and sell the car and buy a Nissan Micra. You get my point!

If you've ever tested an SU with points on a bench with the cover off, it always amazes me how many sparks are created by the points working, just a inch from the fuel!

I'd get a burlen fuel service kit and rebuild the current pump. The only advice I'd give is:

Don't use Silicone to seal the diapgram..it'll send long strands into the pump valves! Use Stag's wellseal or something that remains sticky and won't block the pump with bits.
Robin Cohen

blimey Robin you've not got much confidence in the pump and/or your rebuilding if you need to always carry a new replacement in the boot :)

your's is one way of looking at classic car ownership and good luck to you but it's not suitable for a non-mechanical like me

I've had more than enough of uncertain or reliable car items and certainly my wife has a long time ago

if you carry the pump you'll also have the car jack, the tools, cleaning materials and so on, then what other parts do you need to carry around taking up boot space and extra weight all the time, where does it end

those that like to tinker and get there hands dirty good luck to you I for one want a reliable car to just drive and enjoy, cleaning, servicing ect. has to be done but not extended beyond what is necessary as far as I'm concerned

I don't carry the car jack or wheel tools ever

or a spare wheel

haven't done for 20 years of daily use, tours, rallies and holidays over many thousands of miles each year

I did used to carry a spare engine in the back of my Skodas in the mid-late '80s though !
Nigel Atkins

1) SU, Facet, Fuel Flow, Carter, Airtex all share one common factor - they are all electromechanical devices that can (and will) fail at any time (usually the most inopportune time) and for any reason. For that reason, I installed a backup pump in line with the SU pump in our MGB, with a switch to select which pump is used (see the article, Backup Pump in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/) after having to replace a pump on the side of a major North/South freeway (read Motorway). Not only was the job uncomfortable, it was downright dangerous and I vowed that I would never put myself in that situation again.

2) Never, let me repeat - Never carry a points style pump as a backup. By the time you need to use it, the points will be filmed over so badly the pump will need to be disassembled in order to get them back in working order. Any of the above listed pumps (all electronic SU pump if it is to be used as a spare) can be used as a backup as they are all electronic)

3) If you are using the OEM, AUF 214 SU pump and having trouble with fuel delivery (and the problems is not a clog in the line or an air leak), then change over to the AZX 1307.

4) If you try to repair your SU pump NEVER use silicone sealer on the diaphragm. In fact, there is not supposed to be any joint compound used on any of the joints in a SU pump, but if the flange of the pump body that the diaphragm mate to is wavy, a small amount of Hylomar will suffice to keep it sealed.

5) If you car is being used on a regular basis, a points style SU pump will give you many years of faithful service. If however, like so many of the colonists on this side of the pond, you only drive your car on sunny Sunday afternoons or put it into hibernation every winter, you need to go to the all electronic SU pump or one of the aftermarket pumps (all of which are electronic). One other alternative would be to send your old points style SU pump to Peter Cole for refurbishment and conversion to solid state. Cheers - Dave

David DuBois

David DB. Yes, come to think of it, I have noticed some bubbles from time to time in the fuel filter. So that's the next thing on the agenda.
When I had the old points type SU it would fill the carb up then stop clicking until the engine was started and fuel was used and it would start delivering again. The electronic one seems never to stop clicking and as I mentioned there are some bubbles, so it does look as if it may be drawing in air somewhere along the line. The metal pipe is new all the way from the pump flexi to the carb flexi, so I'll do as you advise and go right through the system from tank to carb.

Bernie.
b higginson

Berni - If you are getting bubbles in the fuel stream and you don't see any wet spots on the fuel line, the leak will be between the tank and the pump (and can even be in the pickup tube inside the tank). Most likely though it will be at a connection between the ridged line and a flexible line, deteriorated flexible line, or even a crack in the turret (it you have the AUF 214 pump) on the inlet side. Cheers - Dave
David DuBois

Bernie

I have a Facet Silver top (electronic) in a Caterham 7, rubber mounted and it ticks constantly. It has done from new and I am pretty sure it's because it's got a bypass in it. I know that they are designed to continue 'clicking'. When you turn the ignition on, it clicks rapidly for a few seconds as the Webbers float chambers fill then settles to a steady click. I would assume that yours is simply doing this.
Robin Cohen

Electronic from Welsh MG £29.50 - no idea what make but fit and forget, no points to faff about with.
Even makes the original tick,tick when priming the carbs! Had one for 3 years and works a treat (that'll have torn it now).

Jeremy
Jeremy 3

Robin - While the Facet pumps do use a bypass valve that causes them to click continuously, the SU pumps do not use a bypass valve, thus they will stop ticking once the float chamber is full and will then tick only as the fuel is used from the chamber. The Hardi (or HUCO) pumps that are generally referred to as a SU type pump operates the same way. Cheers - Dave
David DuBois

I really cant be bothered reading all the stuff above in detail. Just service or replace with original or the modern electronic equivalent and get on and drive your car, all this stuff about pressures, bubbles, etc is irrelevant when you drive what is essentially a stock car. These cars were not complicated when new, why try to make them so now?
S G Macfarlane

Hi Wayne, sorry not been in touch, the number I have for you is incorrect. Can you give me a call on
01616818015, or 07808243789 so we can arrange to meet.
Cheers John Hall. Manchester
HALL JOHN

Cheers everybody,
Facet cube pump fitted with new flexy fuel hoses and stainless jubilee clips.

Thanks again Wayne.
W Williams

This thread was discussed between 22/05/2011 and 28/05/2011

MG Midget and Sprite Technical index

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