325e randomly won't start, changed almost all the sensors

[ferrarix99]

Hello guys,

I have a slightly tricky issue that I'm dealing with. My 87 325e will randomly not start. It's a motronic 1.0. Some background info:

Happens when the car sits longer than a day. If I drive the car every day it starts no problem.

Appears to be related to temperature/humidity.

Changed the crank sensor, all coolant temp sensors, cap, rotor, sparkplugs, wires, hp fuel pump, 3 main relays in that separate box.

Noticed that when its having its little fit the hp fuel pump is not kicking on which leads me to believe it's an electrical issue somewhere up the line telling it not to kick on.

Any input you guys may have would be very helpful! Thank you!

[Andy.B]

Crack open the dme and check for corrosion inside. You might have a failed/failing dme.

[ferrarix99]

I will definitely give it a look over. I have been looking into ecu doctors and their rebuilding service. Any recommendations to get a rebuilt dme?

[Andy.B]

For an eta, I absolutely wouldn't bother. There are enough people ditching the motronic 1.0 for 1.1/1.3 that you can buy a whole stack of used 027 dme's for the price of one reman unit. I had one fail due to corrosion, and unfortunately just sold my good one (with a chip) for about $30 shipped. Hit up the classifieds and snag a used one if you need one.

[603Racing]

Check for power coming to the fuel pump relay when it does it. Sounds like it could be a short, wiring or ECU as previously mentioned.

[jprastrullo]

this might sound dumb, but have you replaced your starter?

[ferrarix99]

For an eta, I absolutely wouldn't bother. There are enough people ditching the motronic 1.0 for 1.1/1.3 that you can buy a whole stack of used 027 dme's for the price of one reman unit. I had one fail due to corrosion, and unfortunately just sold my good one (with a chip) for about $30 shipped. Hit up the classifieds and snag a used one if you need one.

From what I've read converting to 1.1 or 1.3 is kind of a pita and I'd prefer just to swap it out as opposed to swapping sensors and redoing wiring. Thank you for the suggestion though. If there is some kind of newer method that is easier I would be open to that but from what I've read it appears to be somewhat involved.

this might sound dumb, but have you replaced your starter?

Sorry, forgot to mention.. Starter is new and car cranks all the time, never had an issue with it not turning over.