Hi everyone,

I saw a couple of recent no start posts I read with interest, but still not sure of next step on my no restart situation. Also worked through the 700 FAQ section. It guided the things I have done so far on my 1991 740 with non-turbo.

Symptoms:
Car starts fine and I can drive to a destination (e.g. go get gas), but when I try to restart after a short interval (e.g., after I have put in gas) it is about a 50:50 chance of being a no restart situation. If I cool my heels for a while (usually 10 to 15 minutes)it starts and I drive home just fine. When I get home and turn it off it might start or it might not.

Here is what I've done so far:

1. Hoooked up ipd fuel pressure device/gague to fuel rail. I have 38 pounds pressure when I pop the hood after a no-restart event.
2. Replaced flywheel sensor with a new one.
3. Exchanged radio supression relay.
4. Exchanged Regina coil device (called an ignition amplifer module or power stage amplifier or something like that?).

Any other ideas on diagnosising the cause of this intermitent no-restart situation?

Thanks for your help.

Mike

I had fuel pressure (39 pounds) and a good spark, but car would not restart until cold. Suspected a relay. Today I replaced white fuel injection relay (second row left) and my problem is solved. Thanks to those who offered ideas.

Mike

Classic symptom of hot power stage amplified.
It might be simply overheating from bad thermal contact (old dried heatsink grease) not helping cool it. It's supposed to dissipate heat into the sheet metal on the side of the engine bay. If it's all hooked up right.

Good luck,
Will
--
1990 740 Turbo, on its way to stock specs, maybe beyond

For your information, that is about how mine - 1990 745T - started declining months ago. At first I suspected bad gas or gas formula, i.e. ethanol, and ran various cleaners through the tank. They helped, or seemed to, and so did switching brands of gas a couple of times. I am still investigating per FAQ, F.Su's no-start book, and suggestions here at the brickboard.

Hey Mike,


Have you tried re-soldering your fuel pump relay? Really easy to do. Check out the FAQ.



Regards, Jon 'Uncle Olaf'

Do the Radio Suppresion Relay while you're at it.
That kills the injectors when it fails.