Hi all,

My car died and I had to have it towed last week. The mechanic I had it towed to is so busy I may have to have it towed back to my house and fix it myself. Anyhow here is what happened.

Car has been running very well - no problems of any kind. (1985 740 Turbo 86000 miles) . I was stuck in a traffic jam for about an hour so everything was fairly hot. When I got back on the highway and hit the gas I had a severe drop in power so I pulled over. I opened the hood and turned the throttle a few times and it sounded fine. I continued and about a mile later the engine shut off and would not restart. While waiting for the tow truck about 30 min, I tried it again and it started. The engine was very smooth as usual. I let it idle and the engine abruptly shut off again after about 1 min of smooth operation. It would not start again. The wiring and voltage are in good shape overall. I did not have any tools with me so I could not check much at the time.

I was thinking it might be the main fuel pump or relay. I am just wondering if anyone had a pump that acted like this or would the relay be more likely the cause or some other part. It does have a new fuel pressure regulator (3 months old or so).

Any suggestions would be appreciated. I read the FAQs and they look very helpful but thought I would ask anyhow.

regards,
Randy

last Tuesday my car would not start and if was fine the days before I noticed when i turned the key to the no position the car sounded differnt so I guessed the fuel pump. I removed the first spark plug and placed it against the headers and crank the engine it sparked so I removed the main fuel supply line and crank the engine hardly any fuel but some came because of the in tank fuel pump. Your problem is most likly not timing or ignition as the car started once and idled smooth its most likly fuel good luck

Those are great suggestions from Chris, but your 1985 car doesn't have a Radio Suppression Relay. Those started in the 1987 model year.

I know that you have new induction hoses, but check them for secure connections anyway.

If you need an extra Fuel Injection Relay, let me know and I will mail you a free one on Tuesday.

Does the tach needle bounce when you try to start the car? It should since the distributor is new.

If the cam is turning and the induction hoses are secure, you have either a fuel problem or an ignition problem. Check for spark, you could have a bad Power Stage (ignition amplifier). I would carefully loosen the fuel supply hose connection at the fuel rail just after you have tried to start the car. There should be lots of gasoline there just waiting to squirt out under high (~42 psi) pressure. If the main pump fails, the pressure will be measly.

Althought it stands to reason that you can't check something that doesn't exist.

Note to self; add more stipulations to posts.
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Chris Herbst, near Chicago.

Thanks for the tips guys. I forgot to look at the tach when I tried to start it. I assume a moving tach means I am picking up a signal off the distributor's sensor - which is new like you said.

What is a good way to check for spark. Can I just connect my timing light and check for flashing? That seems like it would be an easy go/no go test for the coil/power stage/ignition coil/wiring. I think it does get those components hotter than usual when you sit in traffic for a long time. When the car is moving I think they run much cooler.

So If it dies and won't start again. I can check the tach and timing light to make sure it's a fuel delivery problem.

Does that sound like a plan ? If I can narrow it down to fuel delivery, I have no problem changing both pumps and fuel relay just to make sure I got the problem nailed. I hate getting such with an intermittent problem.

Thanks
Randy

"Thanks for the tips guys. I forgot to look at the tach when I tried to start it. I assume a moving tach means I am picking up a signal off the distributor's sensor - which is new like you said."

Yes, that will at least verify the Hall effect/

"What is a good way to check for spark. Can I just connect my timing light and check for flashing? That seems like it would be an easy go/no go test for the coil/power stage/ignition coil/wiring. I think it does get those components hotter than usual when you sit in traffic for a long time. When the car is moving I think they run much cooler."

The timing light check should be okay, but the timing light will work even with a weak spark. I like to pull a spark plug and watch and listen for a nice hot spark.

"So If it dies and won't start again. I can check the tach and timing light to make sure it's a fuel delivery problem."

Yes.

"Does that sound like a plan ? If I can narrow it down to fuel delivery, I have no problem changing both pumps and fuel relay just to make sure I got the problem nailed. I hate getting such with an intermittent problem."

Yes.

If you still have the original Fuel Injection Relay in the car it will have cracks in the solder joints, I guarantee it. Remove the Fuel Injection Relay, and remove the white cap. Use a magnifying glass and you will see cracks in the solder joints where the larger pieces of copper protrude through the printed circuit board. Re-solder the bad joints. It may not be your problem this time, but it will stop future problems.

Thank for the info. That gives me an idea. I think I am going to keep an old spark plug and ground wire in the trunk so I can just pop a wire on the spare plug rather than removing a plug.

Thats interesting about the relay. I wonder why there are so many solder failures - temperature cycling, high current, and vibration I suppose. I wonder if the solder used in a wave soldering machines is more prone to mechanical failure than your typical rosin solder. I may just bring the car back home and fix it myself since the mechanic is too busy.

Thanks,
Randy

In addition to Chris' list, think about the hall sensor.

1. Fuel pressure relay
2. Radio interference suppression relay (since that is under the hood)
3. Pump
4. Ignition related issue.

My bet goes to the first two, but until you establish the conditions it has when it doesn't run, it is hard to figure out what it might be. There could be other causes as well.
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Chris Herbst, near Chicago.