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MG Midget and Sprite Technical - 1500 Cutting out on roundabouts

1979 midget 1500 owned by my close friend since 1980 has developed an odd fault. Standard set up.
On going round sharp roundabouts and right hand corners the car cuts out for a second or two and restarts. The length of time of the cutting out is getting worse.
All the obvious things have been checked on car both fuel and electrical.
Any ideas?
G R Wilder

See thread "Dash and steering wheel with pics" and try the roundabout the other way round.
Alex G Matla

Alex
How does this thread help?

I am afraid we have nooption with roundabouts in the UK - could be amess we some went the other way.

George
G R Wilder

is it fuel or sparks? what happens to the rev counter needle when it cuts out?
David (davidDOTsmithAT stonesDOTcom)

Does it cut out completely, as if both carbs are starving? Or does it stumble, as if one carb, etc.? If it's a fueling issue, losing both carbs would seem to suggest that the problem is upstream of the carbs.

How much fuel is in the tank when this happens? Taking a roundabout clockwise will slosh fuel in the tank away from the pickup tube, and if there's only a little bit of fuel in there, it could leave the pickup sucking air.

David's point is good, by the way. If you can verify that the problem isn't electrical by watching the tach, that will help isolate the actual cause.

Best of luck,

-:G:-
Gryf Ketcherside

If it is only on right hand bends then check the coil.
A strange fault I had some years ago on a frogeye. It related to the oil in the coil causing a short. Took me ages to discover.
Alan Anstead


Thanks for your ideas.

Some replies to the ideas suggested

Haven't been quick enough to see rev counter so far.

Sharp cut-off and return of power, so more likely electrical than fuel.

Tank almost full the last time it did it.

Coil fault sounds a possible. Would that take the rev counter out?

Any other ideas?

George
G R Wilder

I'd also check your engine mounts. The engine could be moving and pulling on or shorting out a wire making something cut out.

Tim
Tim Michnay

the rev counter works by sensing the pulses as the coil switches for every spark, so yes a coil problem means the tach drops to zero. No sparks, no pulses, nothing for the tach to read.
David (davidDOTsmithAT stonesDOTcom)

I suspect Coil as I have had exactly the same problem as Alan some years ago on a Mk1 Cortina GT, the other things it could be are bad connection on the Low Tension side of the Ignition or a break in one of the Low Tension wires. Finally check the little earth wire on the distributor base plate.

Mark.
M T Boldry

Hi,
I had this and it was fuel and the pump was old and not strong enough to push the fuel through against the G force going round the roundabout.
Tim Fisher

Tim

What about the residual fuel in the float chambers... enough to keep the engine going for a short period...

A
Anthony Cutler

All
Thanks for all your suggestions. Will be having a very good look this weekend/holiday to check all possible solutions.
George
G R Wilder

The car has had a through check this weekend for broken wires,engine mounts, earth straps etc. The car was run in the garage and was tested by pushing down hard and quickly on the bumpers to simulate going round a roundabout.
Could not find any faulty wires etc or make the car cut out.
The only thing not tried is the coil - need to borrow one to test this theory. Then road trials with a passenger who can watch the rev counter.
Any other ideas?
George
G R Wilder

This thread was discussed between 25/08/2009 and 07/09/2009

MG Midget and Sprite Technical index

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