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Sputter and die

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philknight

Jedi Hopeful
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My 73 TR6 engine loses power and then stalls after warming up and running a few miles. If I let it cool down a bit it will start and run well until it warms up again. Thought it might be a problem with the optical electronic ignition installed by the dpo and in removing that realized that the wiring in the car had been hacked up so much that replacement was required.
This is what I've done/installed so far.
new main harness from British Auto Wire
Petronox ignition
New spark plug wires
new sport coil
rebuilt original fuel pump
new fuel filter
blew out fuel lines from the fuel pump to the carbs
adjusted floats
replaced float valves
replaced diaphrams
replaced vacuum lines
installed heat shield
timed at 4 deg atc
then timed at 4 deg btc
Everything seems perfect until I'm about 10 miles from home and then it sputters and dies. It's fun to limp home a half mile at a time. Any Ideas?
 
I once had a "restored" TR6 delivered to me that had almost everything fixed on it. Everything but that little piece of rubber hose from the down spout of the fuel tank to the back of the steel fuel line. Pulled that out, put in a $.50 piece of rubber fuel line and varooooom. It is usually the little things that cause big problems.



Bill
 
I've opened the fuel cap when it's happened and their didn't appear to have a vacuum. and i've disconected the fuel line and pumped the lever on the fuel pump to see if it was clear and everything was fine.
 
I recall the OEM carbs have a thermal compensator or something to that effect. Been awhile since I rebuilt them but the devise was under a plastic cover on the side of the crabs'. This was on a '74 but I think '73's are the same. My '74 has a temp actuated switch that keeps the timing retarded until the motor warms up. If the '73 has that you might want to check for vacuum leaks. You know, it could be the condenser in the ignition system or since many people have had trouble with ignition coils, it may be suspect too.
 
[ QUOTE ]
...loses power and then stalls after warming up and running a few miles. If I let it cool down a bit it will start and run well until it warms up again.

[/ QUOTE ]

Sometimes brand-new just out of the box electronic components can be faulty. My first thought is the coil.

If you have a spare coil you might take it along. Rubber-band, bungeee or duct tape the spare right next to the current coil. When the engine dies promptly move the connections to the spare and see if all is well.
 
Have you checked fuel pressure? You might be pulling in air from a cracked or broken fuel line (between pump and tank).

Bill
 
Thanks for the replies.
The petronix ignition doesn't use a condenser,unless I didn't install it correctly. I've switched coils with no effect, i've run the single vacuum line directly to the distributer, and I did a visual inspection of the fuel line to the tank and it looks fresh. I just recieved a ss shroud from Good Parts in the mail today and I had them provide a hole on the carb side to provide cool air across the carbs out of concern that the headers are radiating too much heat right where I want it least.
Phil
 
When I removed the existing optical electronic ignition I installed points and condenser. The timing wavered 1 or 2 degrees so I switched to the Petronix ignition. with that the timing is rock steady. With all 3 ignitions I have the same condition. Is there a fuel pressure gauge I could install in line just before the carbs to monitor when my gremlin rears its ugly head?
 
You can get a pressure guage from any automotive store and test the pressure while the car is sitting in your driveway. Also you should check the volume of fuel that is being pushed through the line. There is enough fuel in the float chamber to allow you to run the car for the few minutes it would take to see how much fuel the pump is pushing in 10-15 seconds. Disconnect the fuel line just before it goes into the 1st float chamber and place it in a graduated glass container. Have a friend start the engine and see much fuel empties into the container. Compare your results to the Bentley manual.
My guess to your problem is a vacuum leak, possibly around your manifold gasket, or at the carbs, maybe even the carbs themselves. I had a similar problem last summer that darned near took the whole summer to locate and fix. Mine would idle ok but as soon as I tried to go anywhere it would sputter so bad I thought I would never make it home. Try driving the car with either the choke all of the way out or the needles in the carbs set to their richest setting and see if that doesn't improve the situation. If it does, chances are too much air is entering the engine from some point in the system. I fixed my problem by using a high temp silicone sealer and carefully sealed the manifold gasket to the head and to both manifolds, then sealed the carbs to the manifold. It made a huge difference in the way my car idles and runs.
 
Sure, any cheap combo fuel pressure/vacuum gauge can be installed with a Tee in the fuel line... but I have doubts low fuel pressure is the problem as I would expect that to be starving at higher RPMs rather than dying when warmed up.

Do you have to use the choke to start the engine when it's cold?
 
I only use a scoash of choke when starting cold, I'll try full choke when it tries to stall. Would the manifolds be tightest when cold or hot? I know the bolts would expand as they heat up but wouldn't it all expand equally or does the aluminium intake not expand with heat? I'll try to retorque them and/or try the silicone trick. I'll also purchase a pressure/vacuum gauge and check that. Thanks, Phil
 
I checked the fuel pressure and it was reading 3.5 lbs. spec says it should be 1.5-2.5 lbs. Per the book I put in additional fuel pump gaskets and got the pressure down to 2.5 lbs. Thinking maybe that was the problem took it for a spin and She was running right. Thought I had it licked petting the dash, good TR and.... deja-vu all over again. Took me about an hour and a half to limp back home. I'll try the high temp silicone on the intake manifold today.
Guess I'll miss "Brits Invade Gettysburg" that going on today. Phil
 
I had a similar problem. My 6 would run fine for 10 to 15 minutes then spit and sputter and try to die on me. Turned out to be the charcoal filter for emissions. Replaced it and all was well.

Ed
 
I threw in the towel, bit the bullet and had it towed (nc through AAA) to Mountjoys autoshop. Turned out to be the fuel line towards the back was crimped where it couldn't be seen without being on a lift. I'll have to invest in one of those ramp/lifts. I'll be cruising the backroads this weekend.
 
[ QUOTE ]
Turned out to be the fuel line towards the back was crimped

[/ QUOTE ]

TAH DAH!! Do I get the award for the correct diagnosis, or what?? Ask me how I knew the answer to that one....


Bill
 
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