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95 525i NO START, electrical issue?

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    95 525i NO START, electrical issue?

    Greetings,

    220K Automatic 95 525i: Drive the car daily about 30 miles. Proper maintenance and served me well during the winter, etc. Drove several times throughout the day with good mileage and no problems. Went to start the car, cranked and cranked and nada. We listened for the fuel pump and no noises.


    Checked the fuel pump fuse (light blue #23) and it was good. Swapped it with #1 (cruise control) and still nada.


    Diag started at the fuel pump relay thinking that might be it and swapped the relay from my E30 into it. The E30 runs with both and the E34 won't run with either.


    The electrical diagrams show that the relay powers fuse 23 (the only one that powers the fuel pump) but this fuse does not get power at all (key on/engine off, cranking, at no time does it receive power.) Measured resistance from relay to fuse and found 4.7 kiloOmhs.


    By unplugging connector into fuel pump and putting a test prob into the power supply into the fuel pump and a test lead where fuse 23 goes we found voltage between the two. We thus believe there is an open circuit from the fusebox to the fuel pump itself. Supposedly there's a connector X14 in a wiring diagram, but we have no idea where it is. There might be resistance or poor connection or an unplugged connector? From the relay to the fusebox there was excessive resistance.


    On top of that the crank positioning sensor had 0 ohms, but would peak to crazy high of 34 megaOhms.


    Even went as far as to use test leads from the power wire to the fuel pump to get it ghetto powered. The fuel pump made a whirrrring noise but did not start the car.


    I know the CPS is giving off crazy numbers, but I don't know if with all these other electrical gremlins that this would be the definitive reason why. Maybe I'm wrong and that's all it is?


    Like I said, this issue happened out of the complete blue. Drove the car all day, parked the car at a friends, went to start again and nothing. The car has served me so well all winter and now this.

    Anyone?

    SC*AR (Schwarz Army)
    No longer stock ride height, rolling as low as a daily driver in New England should without worrying about breaking an oil pan. :up:

    #2
    Maybe Bimmernut.com would be a helpful place to check. The e34 forum is very knowledgeable there. On my 535, I'd say you have a fuel pump issue and check the fuel pressure. You have to tee into the line on that one to hook up the gauge. Do you have spark? If not the CPS is an issue. Maybe pinch off the return line from the fuel pressure regulator just in case it's gone bad. I wouldn't drive it like that but it would zero you in.

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