1997 328is Engine won't start

Giorgio · 10-05-2010, 08:58 PM

Car was running good and Engine light was not ON and suddenly the engine just died. Battery and starter are good. Checked the DME main relay and there is voltage at terminal 30 and NO voltage at terminal 85 or 86 (there should be voltage on these terminals when ignition is off). Checked the B+ start junction box and power distribution box positive power post and there is battery voltage. Can somebody give me suggestions where else to look?

Manolito · 10-05-2010, 09:11 PM

It sounds like you must have done some detective work to get to the DME (e.g. the fuel pump is spinning up, right?) Can you list what you checked and what you found on the way to checking DME terminals?

Giorgio · 10-22-2010, 10:17 AM

I found out that I am testing the wrong relay sockets. I was relying on the picture of the power distribution box in the service manual book that I used. So I decided to unplug the Three sockets that are lined up together (fuel pump, DME amd O2 sensor heater relays) and looked underneath the sockets for wiring color code (electrical wiring diagrams) . Everything went well and I was able to diagnosed that the fuel pump is not working. I am sorry I was not able to reply to your questions right away because I got sick. Thanks Manolito.

andyr_negro · andyr_negro's Garage

Did you check the Crank position sensor and the camshaft position sensor? That's something common in many cars.

Giorgio · 11-03-2010, 09:00 AM

I replaced the fuel pump and the car is running good. The lesson that I got from diagnosing this problem is don't rely on the position of the relays in the book. You have to look underneath the sockets relay and use the electrical diagrams (wiring color code)to make sure you are testing the right relays, thanks.

bazar01 · bazar01's Garage

Quote:

Originally Posted by Giorgio

I replaced the fuel pump and the car is running good. The lesson that I got from diagnosing this problem is don't rely on the position of the relays in the book. You have to look underneath the sockets relay and use the electrical diagrams (wiring color code)to make sure you are testing the right relays, thanks.

The DME relay can be jumpered to test that the fuel pump is working. We do it all the time on Porsche Bosch motronic systems.