Ok, I have been fighting some electrical gremlins.

74 2.0L FI 037 brain (now with 270 ohm ballast resistor)

The car runs great for 10-15 minutes then dies.

I tested the power relay and fuel pump relay and fuel pump itself and have power to all.

After it cools off for 3-5 minutes it will start again.

I have not checked for spark, but am guessing when it dies this is what is stopping.

What could this be??? ECU / Brain / Computer? I know they rarely fail

When I unplug my air intake sensor it has no affect on running. I thought maybe another sign of potentially a bad ecu / brain / computer. I have read it is supposed to richen the mixture.


Here is a pic of my car just because I like threads with pictures.
Click to view attachment

Points or electronic ignition?

Possibly a bad coil (although some say coils "never/rarely" go bad). I replaced my coil recently (and new spark plug wires) and now my idle/lumpiness of my 2.0L has really smoothed out.

Have you looked through this site? http://members.rennlist.com/pbanders/djetparts.htm#setups

Make sure you ECU and MPS match.

Fuel filter, pump, tank outlet or some other restriction in fuel flow. Check the vent in the gas cap and fuel pressure at the engine.

CHTS (Cylinder Head Temp Sensor)
Or
AAR (Aux Air Regulator)

coil, and they do go bad. runs fine cold, as engine warms up, coil expands,windings separate discharge breaks down. cheap easy check before getting into chasing sparks in the dark, swap coils and rule it out first.

Go to the Anders site and use the flow chart as suggested.

...then come back......

My .02.

Temp II sensor. Try jumping the fuel pump relay and see if it stays running

Intake air temp sensor has a small effect on mixture. Head temp sensor has a very large effect.

Check to see if it is in fact spark that you are missing. Use an extra plug, taped with the outer electrode or threads on a ground, hooked to a plug wire. Crank the starter, watch for spark.

--DD

vapor lock?

How does it die ????
Spitter... Sputter.
Or off like a light switch?

My bet is faulty gas cap (try runnning it with the cap off and see if it stays running) or faulty coil.

When I rebuilt my 73 2.0FI I had the same exact problem. After getting everything as perfect as I could. It still died after 10 minutes. I messed with everything, focusing on the Temp Sensor II. But everything always checked out as fine.

With nothing left to fix, I thought, I finally went and rented (It was free, but needed a deposit) a fuel injector noid light from Auto Zone. It showed that power to the injectors was random after it warmed up. Sometimes it went on then not for a while then on again. I thought it could be the harness, but that tested okay.

So I took out the distributor and cleaned and checked the whole thing. The trigger points were really dirty, out of position and not working correctly when I tested them. After I got it set up perfectly, cleaned the trigger points, got them set just right, and put everything back together. The car ran perfectly and has for the past year.

That just goes back to the adage with D-jet that you should check everything mechanical first......everything including the valves. Glad you found the problem. That was my suggestion to the OP.

not to hijack the thread but...I have this same typw of issue with my car and I am running Weber 40s.

If warm and car is idling, after about 5 minutes it begins to sputter, revs drop like it's going to die. If I let it go it corrects itself after 10 or 12 seconds; then fine for another 5 minutes.

Happens when I am driving to...feels like car misses a beat or two then carries on.

It started out of the blue. I have fuel at the carbs at 4psi...have a gauge.

So maybe same type problem even tho its carbs.

Now I am thinking coil or condenser is going bad.

Read somewhere here that the coil should be mounted vertical...mine is more horizontal.

Its a new coil with maybe a few hundred miles on it.

When this happened to me, it was crud in the fuel tank (tiny particles of metal that got past the "sock" and then cut thru the filter to the fuel pump) causing the pump to get blocked and over heat and shut down.

I did one better and jumped the fuel pump itself, as it was starting to die. No change.

Somewhere in-between. Closer to the light switch.

Try borrowing a coil from another member here. Also, have a look at your fuel filter and see if it is clogged.

good suggestion! I didn't think of this. My coil only has 15,000 miles on it and is shiny new looking, so didn't even consider it. Then again, that is over 7 years. That would be a cheap easy fix.

CHTS..........Just saying!!

Thanks to all for the numerous suggestions. I can always count on the faithful members on this wonderful site.

Thank you!!

I will report back when I find the problem.

I tested the Coil and it has power when the car dies. I hooked up a volt meter to the +. I was really hoping that would be the problem, as it is cheap and easy.

Someone suggested the CHTS. I thought these worked or didn't. They have a resistor built in, as I understand them. I replaced mine 15,000 miles ago.

I had this exact thing happen to me driving from LA to OKC.
Runs for ~10 minutes, sputters & stops, wont start.
Wait 30 minutes starts right up and runs for 10 minutes.

It was crap in the gas tank

It's almost certainly fuel. You have some blockage, the gas cap vent, the fuel tank outlet, a kinked or deteriorating hose, a clogged fuel filter. The fuel pump will build pressure but the engine consumes more than the reduced supply, so the pump will suck but because of some restriction there's no fuel available to flow. So the engine is starved, dies, and while not running the fuel will seep by, the pressure will equalize so it can start again, but without enough fuel to keep running.

Because it runs for ten minutes the electrical possibility would probably be related to heat, affecting sensors, the coil or condenser. but then it shouldn't run again until cool. From your description it's almost certainly fuel.