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MG MGA - Ignition switch

I have noticed once or twice during the year that they car does not fire from cold first start of the day. Turn off ignition. Turn on again and instant success. No other issues all day. Well, yesterday I was driving in traffic when I felt the engine gradually fade. Pulled over with engine barely spluttering. As I stopped so did the engine. Recycled the ignition key. Pulled starter and immediate fire up as if nothing had happened. No return of the issue afterwards.

Question. Is there a history of ignition switch issues causing this sort of thing? Seems too coincidental to be anything else.

Steve Gyles

I had similar with my pushrod A. It was crud in the fuel line at the point where the pipe from the tank curved to connect to the pump.

Symptoms were slow loss of power, to a splutter. Stop, re-start and everything was good again. It was almost a perfectly shaped internal 'plug' of metallic dust that was letting some fuel through, but not flowing enough when under load.

A good airline burst through all the other (separated) pipes revealed no other restrictions.

Colin Manley


Worth a check, although it's a new tank (2 years old).

I still suspect the ignition switch though. I recall occasionally that the ignition light does not come on. Switch off then on and all ok. Rather odd because the pump always ticks when I switch on so I presume its alright, but no.

Steve Gyles

Next time it dies out, check the fuel gauge before you touch the switch. If the fuel gauge is working, the switch is on, and you have a different problem. If the fuel gauge is off, try "tickling" the switch (just a little wiggle on the key) to see if it makes the connection. If that works, then you may need a new switch.

Sounds unlikely to be the ignition switch Steve, although with an MGA you can never say something is impossible.
Whenever I have had any ignition problems the engine would either just not fire at all, or just have a consistant misfire.

Intermittent fuel flow is more likely, usually something floating around in the pipes or a fuel filter if you have one fitted.
If you have a glass in-line filter fitted like mine, I would still take it apart to check what is in there even if it looks clear.

Mine is also a brand new Moss fuel tank fitted at around the same time that yours was.

When I had the same problem about 10 years ago, I found a large piece of transparent silicone sealant floating around inside my in-line filter.
It was absolutely invisible floating around in the fuel but it was large enough to gradually block the pipe as it moved with the flow and cause the engine to drop onto 3-cylinders, then 2, then 1 until the engine died.

Then if you switched the ignition off, the fuel would stop flowing allowing the silicone to gradually drop down to the bottom of the filter and the engine would then start up and run fine again.

Coincidentally, I have just replaced the in-line filter on my MGA for a new one to fit my newly installed fuel line and the picture attached below shows how effective it had been. The junk in it has built up over the last 3 months or so since I last cleaned it out.
(You can see the black triangular bit of debris inside at the Rt side plus what looks like a piece of thread and lots of little black specs)


Colyn Firth

I hate these sort of faults. Checked it out yesterday and could find no issues with fuel supply. Went for a good run and could not reproduce the symptoms. Purred like a kitten. The trouble is it knocks your confidence in the car. Sitting there waiting for something to happen; imagining the likely scenarios pulling out of a junction; middle of a roundabout etc.

I did solve one issue about the ignition light not coming on when turning the key. It helps if you look at the left dial with appropriate lens rather than the high beam lens on the rev counter!!!! Brain going diddly squat.

Steve Gyles

Steve, on my car the high-beam warning light is in the speedometer and the ignition light in the rev counter.
They were originally both red which I found to be confusing at night.

So I solved that issue by having the red high-beam light lens taken out of the speedometer and swapping it for a blue one and so now I can instantly tell which is which.

I believe that both of the warning lights were factory fitted with red lenses, there must be some logic in that choice but I'm not sure what it is.

Colyn Firth

Sorry, I forgot to add that, similar to your problem, occasionally my ignition switch seems to have a poor connection causing the engine to falter.

I then realised that I wasn't fully turning the key because the switch was slightly stiff in operation.
Once I turned the key firmly for the last couple of degrees the switch works fine.

Probably the stiffness in the switch is down to it being a repro part.

Colyn Firth

Thanks Colyn. I confused myself. As you say Ignition on left rev counter and high beam on the right! I somehow got it in to my mind to look straight forward for the ignition light rather than glance to the left. Never the strongest of lights, especially in bright daylight. I find the same with the turn indicator bezel.

My ignition switch is the opposite - rather sloppy. I need to check my used parts bin as I have a vague feeling from the distant past I put my old original barrel into a new holder.

Steve Gyles

Check and make sure the wires have a good connection to the back of the switch. Seems like you may be running out of fuel in the float bowls because the fuel pump isnít getting power. Then when you stop and restart, the connection in the switch is somehow restored and the fuel pump starts again.

JL Cheatham

Following on from Jim's comment I had a similar problem and it was a slightly loose wire to the switch. I only discovered this as I was fitting a new switch!

Paul Dean

This thread was discussed between 08/09/2018 and 12/09/2018

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