Hello! I've got a problem with my '85 740 Turbo, which has 248,000 miles.

It all began with the motor suddenly quitting while driving and then abruptly restarting before it slowed down enough to pull over(the dash lights didn't come on). Eventually, this behaviour became more and more frequent until the car would quit and have to be restarted every 100 feet or so. Finally, it just wouldn't restart and I had it towed to my mechanic.

I suspected a clogged fuel filter at this point...

My mechanic replaced the fuel filter. He also replaced the plugs, ignition wires, cap, and rotor , which were all in unusually bad condition(Very badly burnt).

Anyway, with this work done the car started and ran fine. It was driven on a 15 minute trip without incident. * I must mention that the temperature was about 15 degrees fahrenheit during this trip.*

What is happening since this initial trip is as follows: The car will run for a few minutes until it warms up, and then it will just quit completely, without any sputtering. After it quits, you can hear the fuel pump continue to run for a few seconds until the relay shuts it off. If you immediately attempt to restart the car with a good plug in one of the ignition wires you can see that it's getting spark, but it won't fire. However, if you wait a minute or two it will start up and run for a short time until it quits again. It seems that the longer you wait before an attempted restart, the longer it will run. However, when the air temperature is about 40 degrees F, it will only run for about two minutes at most.

I hope you can be of assistance...This is my first time on your site and it is absolutely AMAZING! Keep up the great work.

Before you start shoveling truck-loads of money into repairs, you need to try and determine if your problem is ignition or fuel delivery related. You can "T"-in a fuel pressure gauge to the fuel injector rail and tape the gauge to the outside of the windshield for monitoring while motoring.

For the ignition side, Don Foster once described on this board a method of wiring up a small neon bulb to one of the plug wires and then you can monitor that from inside the car also. Check the archives for that one.

You may want to just go ahead and resolder the fuel pump relay right from the start to see if that is the culprit. It may work fine when cold but fail when hot. (Check the archives on that one too.)

"...once described on this board a method of wiring up a small neon bulb to one of the plug wires..."

Yes, sort of. You would NOT connect it TO a plug wire, only run the neon bulb lead NEAR the plug wire (I wrap the neon bulb lead around the plug wire insulation about 10 times).

This picks up the spark pulse by induction, kinda like an "antenna."

Don Foster (near Cape Cod, MA)

Now there's a small detail I omitted. The bulb would have flashed .... once ...... real bright ..... with smoke?

I dunno. Let us know once you've tried it!

Don Foster (near Cape Cod, MA)

I had the exact same problem with a 1986 wagon. What it turned out to be was a dirty ignition switch block connection. To solve, reach under and behind key switch and gently rock the ignit. switch connection off of the male prongs. Use a good electrical connection spray cleaner and reassemble.