MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Stalling problem

This is not an MGB problem however it is not necessarily car specific and I was always impressed my the amount of good advice provided on this BBS when I owned my 73 B.

My 75 TR6 starts easily when cold but often stalls when hot and is then a pig to restart. Often OK if I wait a while. I know that the tappets need adjusting since they are quite noisy, hoever, this has been the case for some time. The engine sometimes misses when pulling away at low revs which makes me lean towards an ignition problem. The cap, leads and rotor were replaced recently and the car is fitted with an aftermarket electronic ignition module (Allison) which has eliminated the points.

Any suggestions for a logical diagnostic process?

Regards,

Barry
BJ Quartermaine

Some MG fuel systems have a vent line, some have a vented cap. If your car calls for a vented cap and your cap is not, a vacuum can develop.

When your warm car refuses to start, open the gas filler cap and listen for a "whoosh".
Dan Robinson

Is this an injected 6, Su's or Strombergs? Sounds like fuel vapourisation could be a possibility. Have a good look at the heat shielding for the fuel lines near to heat sources. Could be faulty coil. Does the coil get hot, i.e., really hot? When it stalls what happens to the tacho? Does it die quickly, go erratic or slow down with the engine?
Al
Allan Reeling

Thanks for the quick responses.

Dan: The gas cap is a unique quick flip type which is the original - not sure whether this is vented or not. Had already checked if opening had any effect.

Allan: Engine has twin Strombergs - I am much more familiar with the SU's fitted to my MGB! Will check out the vaporisation suggestion - I don't beleive that there is a heat shield over the exhaust manifold as on the MG but will have a look.

Barry
BJ Quartermaine

I had a similar problem with my 'B with the original '
Stromberg. Turned out to be a scratched needle. HTH

Jim
JMcHugh

Also check the diaphrams for holes, stretch then slightly by running your finger over them.
Allan Reeling

The Stromberg carburetors, used on N.A. TR6 applications, have a hot air bypass valve, that comes into play when the engine heats up. These can become problematic, over time, and cause poor running conditions. Any good rebuild kit will come with everything needed to get the carbs running as close to new as possible. There not the greatest carbs when new, but I've worked on much worse designs. RAY
rjm RAY

Thanks guys. Problem on hold until I set the valve clearances and then undertake a logical process. WIll update later.

Barry
BJ Quartermaine

I believe that the problem has been solved. Valve clearances checked and only minor adjustments required. The coil was replaced with some perceived improvement but then stalling returned when hot. Based on specific local advice, I replaced the carb diaphragms since they appeared to have a tiny crack at the fold. The engine now idles so much more smoothly and pulls away without the previous hesitation and stumbling. No stalls experienced todate even when crawling through town on a hot day in Sunday afternoon traffic. I will keep my fingers crossed. I also replaced the rotor with the blue upgraded item as a hedge against future problems with reported substandard items.

Thanks again for the advice.

Barry
BJ Quartermaine

I forgot to mention that Allan R gets the prize! I'm heading your way shortly - Cambridge area, my hometown.
BJ Quartermaine

This thread was discussed between 23/05/2011 and 07/06/2011

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now