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Bad coil mimicking fuel starvation?

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tdskip

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Hi folks - have the bard find TR6 out for a while today. She, of course, died on me again. She starts fine and runs OK (lumpy - but that is a bad spark plug wire) until she has been running for around 10 minutes and then her power fades and then just dies.

I was thinking fuel but that doesn't seem to be the issue. I thought from other posts here that this could also be a symptom of a bad coil... Any ideas?
 
I had an old Dodge that acted like that. It turned out to be a bad fuel pump. The diaphragm had a tiny rip in it. It would pump for a while then gradually it stopped. Once cool the pump functioned again. Also the higher the RPM the less fuel it would pump.
Don't know if that is your trouble but might be worth a look.
Hope you solve your problem! /ubbthreads/images/graemlins/hammer.gif
 
Thanks Roman. The fuel pump is new from Moss, but I shouldn't assume it is working OK I guess. (it does keep the filter full of fuel however...)
 
Ok, so the fuel pump is probably not the problem.
How is your fuel tank vent system? Is it intact? Do you have the charcoal canister connected? Is it clean? When you pop open the fuel cap do you hear a whoosh sound? If you do then you have a fuel tank venting problem. If you drive with the gas cap unlatched the car will keep running.
Sorry about all of the questions I am just trying to eliminate fuel as a cause of your troubles.
 
I'd replace the coil...It's a cheap, easy task and it will give you a good place to start. Bad coils have given me tons of problems throughout the years. Heat tends to break down coils so if it's only happening when the car is warmed up this could very well be your problem.
 
Thanks guys.

New coil is on its way!

I'll have to check the fuel tank vent system - I recently hooked it up after having tank dipped.
 
Fuel mixture too rich? Choke sticking? (just thinking maybe mixture becomes too rich after the engine warms up). Cracked distributor cap? Just thinking about things that have happened to me. Also check the primary and secondary wires to the coil for corroded/loose/broken connections
 
Hi Skip, I think its going to be tough to diagnose the problem if you have so many variables.
You are apparently trying to run the car with a plug wire you know is no good, what else might be no good? I think you will need to change the carb. diaphragms, plugs and wires, points, condenser and distributor cap just to get these things off the list of possible causes. Then you should be able to zero in on the problem.
(I hope the tone of my post does not sound critical, it is meant to be helpful advice so you don't waste a lot of time looking for the wrong solution!)

Good luck! Simon.
 
I'm having the same problem with my TR6 right now (see"Non-Running Diagnosis). I have replace the coil. Still nothing. I'm going to start looking at the fuel side now.
Reid.
 
Whenever I hear "Runs 10 minutes, then dies" I automatically think "Ballast resistor". 10 minutes of run time is just enough to heat a coil/points/condensor until it's all so hot it can't function anymore.

I hope that new coil you're getting is internally ballasted.

JACK
 
I dont know if this will help...but the same thing just happend to me...fuel tank boiled out and all the little bits cloged up the new fuel filter in 30 miles. I replaced that 3 dollar part and everything was fine. Gubba
 
It's not the ballast resistor, that heats up and knocks the voltage down to about 9 volts, which is about how much the points can handle long term. If the resistor burns open then no spark. Get a spare plug and a long plug wire and when it craps out put the plug wire in the distributor cap and ground the plug on the body. You need the long wire so you can see the plug gap while you crank the engine.

If you have some help you won't need the wire, or if you have jumpered the starter solenoid so you can crank from under the hood. Just stick the plug in one of the wires. Just make sure the key is on and it's in neutral.

My guess is a coil or the cap, carbon button breaks down.
 
Well I changed the coil, cap, rotor, condenser, plug wires and double checked the timing - and she's still dying when she warms up.

If I let her sit for even a minute or two, she'll start right up and then die again after a shorted time period.

Carb diaphragms are OK, and no venting noises from the gas tank. If I leave the gas cap lid open it still happens.

Argh!
 
What is the condition of your fuel lines? I was experiencing the same symptoms and it ended up being the ONE fuel line (tank to pump) that was not replaced. The clue was the color of the fuel in the pump bowl, which was orangish-brown from the varnish/gum rather than good ol' clear gasoline.

Good luck.
 
I'll throw my hat into the ring with:

Has you checked your gas tank for something peeling off the inside and clogging the pickup/lines? My first TR3 would do the exact same thing, and it turned out the fuel tank at some point had been sealed with a rubber-like material (to prevent leaking and rusting.) The material had begun to break apart and it would clog my lines just enough to reduce the amount of fuel to the point of starvation. Give it enough time, and the fuel would work its way past and run again. It would die randomly. With a new tank, it ran perfectly.
 
Hi guys.

I had the tank dipped, so that shouldn't be the problem. BUT, Jeremy the fuel in the filter does look a little orangish-brown still.

Let me try blowing out the fuel line again.

Thanks for the coaching.
 
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