Misfiring and cutting out

[Paulspooner]

Can anybody help. My tr4a, reliable for over 10 years in my ownership developed a problem last Spring where after driving about 20 miles it would begin to misfire and soon after would cut out completely and refuse to start again for 15 minutes. After which it was fine and the cycle began again. The problem has slowly become worse throughout the Summer and now I cannot even get to the end of the road! I have changed every part of the ignition system; coil, leads, plugs, points, condenser, dist.cap and arm. There is fuel in the carbs. I have reached the end of my knowledge. Any ideas?

[dpb]

I had similar problems, which I though had two causes: 1) turned out to be firstly a failed or failing condenser, followed by faulty from new condensers. This caused misfiring from the off. Fitted electronic ignition in the end. 2) not starting for 20 minutes or so after a run, which I put down to fuel vaporisation, but honestly never convinced this was the real cause, and still suspect the condenser.

 

Dave

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[Icarus60]

Paul

I wonder if you have a blocked filter in the fuel line somewhere. When you initially start the fuel flows ok and the engine starts but as the fuel continues to flow it deposits crud on the filter face and then after a time the filter eventually blocks and the engine misfires and stops. The crud then slowly falls away from the filter face and the car will start again and the cycle repeat itself.

Might be worth a look - Best of luck

 

Rog

[Peter Cobbold]

Paul,

Welcome to the forum.

At least you have a consistent problem so it should not take too long to pin down. Next time it fails immediatley check for sparks - it might be a poor connection or weak ign switch that has steadily deteriorated. If no sparks, measure the voltage at the wire detached from the SW connector the coil.

If you havent changed the short, thin woven wire on the disy moving plate, do so. That can fail erratically.

Unfortunately not all repro parts are good out of the box, so we might need to revsit the new ig parts you have fitted.

I tend to suspect sparks before SU carbs.

Peter

Edited October 4, 2015 by Peter Cobbold

[RogerH]

Hi Paul,

either fuel or sparks

 

For the fuel - 1, very carefully look inside the fuel tank to see if there is a fungal mass blocking off the fuel.

you could disconnect the tank outlet pipe and see how the fuel flows.

2, Next time it happens very quickly flip the fuel tank cap and listen - did you hear a suck of air. The tank should be vented. If blocked the fuel eventually stops. Run with the cap undone and see what happens

3, To ease the difficult starting after stopping pop the bonnet open - leave on its catch. This will allow the hot air to escape.

 

Sparks - you must suspect ALL elecy items whether new or old, used or unused.

Get new rotor arm, capacitor and points form Martin Jay (AKA the Distributor Doctor).

Most coils work OK - the Lucas gold sports coil normally works out of the box.

As Peter C states check that flexible LT wire in side the dizzy - remove and inspect the terminals very very carefully.

 

I bet it is the non-venting.

 

Roger

Edited October 5, 2015 by RogerH

[Paulspooner]

Thanks, any idea where I might get a replacement thin woven wire and what it is called. I will try the fuel filters as well.

[stillp]

Speak to Martin at Distributor Doctor. I've been having similar problems, and have renewed points, plugs, plug leads, dist cap and all the LT leads. There are 2 thin woven wires: one on the bit of white plastic that has the LT lead from the coil, and another attached to the baseplate. A new baseplate is £lots, but Martin sells a supplementary wire.

 

 

Pete

[ctc77965o]

i would suspect the Condensor - the new parts are **** quality.

Also check that the coil is the right way round..