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MG Midget and Sprite Technical - engine will not turn off

hi,any body any clues to why car will not turn off when running it seems to have decided to do this all by its self while away for the winter. forgot to say its a 1974 1275 RWA.cheers andy


a moverley

The fuses have been connected together and now the ignition is permanantly live so once started then it will keep running until the battery is disconnected or dynamo/alt is disconnected?

I am sure you must have done something that has caused his problem please try to recount everything you have done or indeed who else may have done?
Robert (Bob) Midget Turbo

Something to do with the wiring sequence between the ignition switch, the ignition warning light and the coil. It sounds like it is set so that with the engine running the alternator is powering the warning light as it should, but the coil is on the same side of the ignition switch so that once running power continues to be supplied to the coil from the alternator even when the ignition is turned off?
Guy

ignition switch would be my first thought
Nigel Atkins

alternator feeding the 'off' side of the ignition switch via the charge light. Fixed in modern cars by a diode in the charge light circuit. I know this because when I started the K up for the first time it would not stop, even after unplugging the battery. A diode fixed it. Don't think A series cars have such a diode so check the charging to ignition circuit as Guy says.
Rob Armstrong

Diode sounds another very likely cause I agree?
To test this disconnect the plug out of the rear of the alternator and see what happens.
Robert (Bob) Midget Turbo

Assuming nobody has altered the wiring whilst sitting still in the winter, then it's the ignition switch sticking on would be my guess. There isn't a diode in the external wiring to the alternator on a 74. -- Unless someone put one in.
Lawrence Slater

Its just the car telling you to use it - not pack it away!!! get out there and dont stop till u run out of fuel!!! lol
Mick - still wiring!!

I don't have any idea opn your problem.....but I want your roof!

Is that removeable?
I'm new to midgets, and never seen that style before
Matthew T

hi,thanks to all will go through list and let you know how i go .
also matthew the roof is removeable and is a ashley hardtop.
a moverley

just stall it

C L Carter

Andy where in West Yorks are you
I'm In Morley (LS27)
Mick - still wiring!!

hi mick.i am in crofton near wakefield so not too far away
a moverley

Well I've kept my mouth shut on this one as mine had started to do the same last summer. I had a plan to swap out the solid steering column and install a collapsible one with steering lock/ignition switch so thought that may fix it.

This afternoon I swapped the columns over, taking my time to get everything lined up with straight ahead.

I came to look at the wiring for the new ignition switch and got confused without evening touching the existing connections to the dash mounted ignition switch.

The only no standard thing is the introduction (when I first build the car 18+ years ago) of a FIA cut out master switch.

Anyway, as I said I didn't touch anything electrical relating to the switch and lo and behold the bloomin thing will only run now when the key is cranked all the way round to the energise the starter point on the existing switch....

Me and Electrics don't mix... I give in!

The road Midget is again parked up until a certain Mr Hiley comes round to no doubt look at me as if I'm some kind of electrical retard and then promptly try to explain it to me where it will go straight over my head again....

I'll try to make notes to pass on to you here.

Ho Hum!
Andrew McGee

Is the engine diesaling... Keeps running but just wont die

If its not wiring.... And it is diesaling, then it could be the timing is to advanced and / or its running lean, which makes the engine run hotter thus making the fuel continue to explode, thus making the engine continue to run... Albiate lumpy

Prop
and and the Blackhole Midget

No Prop it's not dieseling, I used to have that on a previous race engine which ran on and had to be stalled to get it stationery.

This is definitely Electrics as it used to switch off on the master switch with no issues. Yesterdays change was that it wouldn't stay running now other than when the ignition key is fully round to the point that it would be kicking in the starter.

A case of the Gremlins I think.

A
Andrew McGee

When the engine is running on, stall it (clutch or whatever).

Now... if it will start on manual operation of the solenoid, it means the ignition is connected/live to coil.

If it won't start, it means that the engine was being kept alive by the alternator.

Worth a try.

A
Anthony Cutler

now sounds even more like ignition switch, perhaps location in/to key barrel
Nigel Atkins

Yes, it does seem like broken or faulty internal connections on the ignition switch in both cases.

My early explanation could well be the case, but only if some changes had been made to the wiring connections - either intentionally or inadvertently! But I am now switching (pun intended) my single transferable vote for the likely cause!
Guy

Might try a little graphite into the key hole...the little barrels and pins might be sticking and keeping the electric from turning off when the key is removed.... I kind unused exterior doors in the spring time like that when they havent been used in awhile in peoples homes... They dont want to completely unlock....its rare, but could be a remote possability for your situation

Prop
and and the Blackhole Midget

hi, just an update just cleaned fuse box and replaced the solenoid and bingo every thing back to normal but have also fitted a kill switch just for back up thanks to all for advice.
a moverley

Andrew,

The new switch is it a 1500/ alternative Leyland one i.e incorrect one for car ?

If so it could be the starter position is using the wire for ballast ignition (wether or not you have ballast), when it drops back to normal run, it would need another wire for ignition feed.

Had the same when I bought my restoration basket - a real 'bitsa' - took me ages to work out why i had a loose (unloomed) wire going to the coil as well as original feed (1275 no ballast coil).

R.
richard boobier

Guy,
you see what happens when we agree :)
Nigel Atkins

Thanks for your various suggestions. I'll try to clarify the current (no pun intended) situation.

Mine wouldn't die when turn the key to off and removing it. It would only die when I killed the FIA master switch.

I swapped out the ignition switch to a brand new one but the situation stayed the same, so swapped it back to the original one and put the new one into the spares box.

I've since swapped the column and installed a new old stock Leyland ignition switch correct for the year BUT NOT connected it as yet so the new column switch has nothing to do with it.

The car now will only run when the ignition key in the dashboard mounted ignition switch is turned and held all the way round to the starter point, as soon as the key is release to it's normal place the engine stops.

As I said previously this is far beyond my limited comprehension now, ballast resistors, coils, soleniods and FIA kill switches have all been mentioned by the AutoElectrican mate who a few on here already know, so I'm going to let him take a look at it and be baffled by his particularly northern dialect expressed diagnosis of what's happened and what I should have done to fix it...

It'll be fine soon no doubt!

A
Andrew McGee

Hunger mice living under the dash

Prop
and and the Blackhole Midget

Oh how embarrassing, but I'm man enough to admit it and you can all take the p!ss out of me now....

someone had put a new fuse box in it and connected all the wires up to it in following the photo he'd taken of it prior to removing the old one.

Only that person put the fuse box in 180° out.... ooops!

That'll be me then!

A.
Andrew McGee

Doughnut... :)

Are you playing at MGCC Brands in May?

J
James Bilsland

Nope James.

Robert is doing his GCSE's so we aren't doing anything until they are done with then plan to be out at Mallory on the telly! :-)

We'll be having a play on our own before that to make sure this PH engine is as good as he says it is.... crossed fingers!

A.
Andrew McGee

Andrew that has turned out to be a cause of problems on other threads so it's not just you

I've fitted something forgetting an important element then redone it exactly the same again, e.g. those electic plug tops that you have to feed the wires through before connecting up
Nigel Atkins

Good luck to Robert with his exams

Will see you at Mallory then - I assume due to your lack of screen and roof you've entered the series in AH Class D or E?

I've entered as an E this year - the race car is now wearing ACB10s :)

J
James B

Yep, we're in the same class again James. So no doubt you'll be disappearing off into the distance again :-)

A.
Andrew McGee

>>The car now will only run when the ignition key in the dashboard mounted ignition switch is turned and held all the way round to the starter point, as soon as the key is release to it's normal place the engine stops.

Sounds like the wires on the switch go to the wrong pins...

A
Anthony Cutler

Sort of Anthony, as I said before and I'm just reaffirming how stupid I am, I'd replaced the fused box and put it on 180° out which was why it wouldn't turn off on the key, this evolved into the not being able to run without holding the key in the energise starter position due to the white lead on the back of the tacho coming adrift. The two combined things caused the issues and the thing that caused those two things was.... me!
Andrew McGee

I remember once having to fix this problem for a customer. It was a broken brake light bulb. The car was an automatic, and it would not turn off at night. The filament had dropped on to the tail light filament. As he was sat with his foot still on the brake in his garage, the engine continued to run. If he had turned his lights off before his engine, he would never have known.
Shawn

This thread was discussed between 05/03/2012 and 18/03/2012

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