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Faltering and stalling engine


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Hello all again,

My TR6 is up to mischief again. 

Car starts ok, and runs pretty well, however after a few miles of driving (and particularly if stuck in a steady moving queue of traffic where my speed is consistent), the engine will have the odd falter and stutter.  If stopped at traffic lights or stationary traffic, the engine can just cut out, literately dying.

Give it a minute or two and she will start up again. 

She stalled right at the lights in my local town at the weekend and much to the annoyance of the cars behind only restarted when the lights went red again !

I am thinking that she may be running very rich, and if running at steady speed then the fuels overwhelms the engine, thus faltering and stalling. 

FYI, there are no loose wires (anymore!), all electrics checked and running sweetly, and injectors spraying correctly (these have just been replaced).

My question: if the car is running  too rich, is there any adjustment that can be made apart from replacing the Metering Unit ?

Thanks, Neil  

 

 

 

 

 

 

 

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If you unscrew your spark plugs, and the tips look all wet and black, then you will have determined if that is the problem, or not.

It is a simple diagnostic starting point.

There are electrical issues about the distributor that could be the problem.

Walt

 

Edited by Sapphire72
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Neil my twopeneth would be blocked filler cap breather or rubbish in the fuel system causing a blockage. 

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There is an old trick for leaning the mixture of putting a strip of shimstock between the cam follower in the 'castle' and the moving piston in the MU. It might be described in the Technicalities CD, it was originally desribed  in TRA back  when it was typewritten.

You have tried blipping the throttle repeatedly to try ot prevent the stall?

Peter

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Thanks Sapphire.. actually yes that would be the most instant diagnosis. I will check the plugs next time it happens. Also, the electrical, the Coil was replaced very recently, and distributor fully electronic, as it has been for a while now. 

Thanks Peter... yes I try to blip the throttle but this doesn't help, it still just stalls. I will try to find the article on leaning the mixture using the shimstock. When you say 'castle' I assume you mean the black plastic cap on top of the MU ?

Thanks Graham....  I think I can rule out crud in the fuel and the fuel cap should also be ok. 

 

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To be honest, Neil, there are an almost infinite number of adjustments you can make to the metering unit if you are brave enough, Peter's trick will give you an idea of which direction to take, it is simply reducing the gap between the cam and the following roller, (I seem to remember that the gap here at zero vacuum should be 57thou) .... Google "Lucas Mk2 Pi" and you can download the full Lucas service manual which gives absolutely every adjustment you would ever want to make, having said all that to get it right the engine must be in good condition, pulling a decent vacuum, and the ignition spot on before making any adjustments to the metering unit.

Cheers Rob 

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Neil,  As Rob says first check the spark timing. Or simply rotate the disy a few mm either way with the engine ticking over, reclamp it at the fastest rpm. Wear rubber gloves and use a dry rag to try to avoid getting a jolt. This method allows for the possibilty that the damper timing mark has shifted. Peter

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Hi Neil,

if your car stops, you can pull one HT lead off and put a good working sparkplug in there, then start the engine (needs 2 persons). If you then have a spark but the engine does not fire (on rhe remaining 5), you can rule out ignition related matters.

Waldi

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1 hour ago, Waldi said:

Hi Neil,

if your car stops, you can pull one HT lead off and put a good working sparkplug in there, then start the engine (needs 2 persons). If you then have a spark but the engine does not fire (on rhe remaining 5), you can rule out ignition related matters.

Waldi

Waldi, By the time Neil has done that the engine will start anyway - see first post. Peter

The problem seems to me to be due to an accumulation of heat in the combustion chamber at tickover, and too-retarded sparks will do that. And as the mixture temperature rises the mixture will burn faster and the timing prgressively more retarded for the mixture. A couple of minutes to cool down and normality is restored- for me that's the clue. .

Peter

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Take off the vacuum line to the MU at the manifold and suck on it and seal the pipe with your tongue, it should hold the vacuum, (or use a vacuum pump)  if it doesn't hold you need to check the diaphragm under the black top. If there is little or no vacuum the MU will run rich.

Also make sure that the enriching lever/cable on the MU returns to rear and is not causing the MU to be running with choke.

Check also the balance of all the throttle bodies with an air volume meter.

John

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