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  1. #1
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    Member No: 152459 mpo702 is an unknown quantity at this point mpo702's Avatar
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    1987 735i No Spark, will not start

    I have a 1987 735i and one day it stopped running and will not start. There is no spark most of the time and when it does have spark it starts for a few seconds then dies then returns to a no spark state! I have changed out most of the relays, but no luck. A friend of mine said he asked a guy who stated it may be the Cold Start Relay, I have looked in my cheap service (Chiltons) and it does not show where this relay lives. Can anyone help me with this problem? I love this car and would hate to have to junk it. Note: I have already changed the spark plugs, wires, cap, rotor, oil, oil filter, air filter etc and that did not resolve the problem.


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    Member No: 58142 ROYinGA is an unknown quantity at this point ROYinGA's Avatar
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    Go to e38.org/e23 and look up the ETM, you should

    find what you need on those wiring diagrams. Have you checked the Main relay first?? It turns on the fuel pump relay and the ECU.

  3. #3
    drharper750
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    switching connections at rear of engine worked 4 m

    me,trans speed/tach/cps.it should narrow it down.cold start is 1st temp sender on engine

  4. #4
    Rick3649
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    Re: 1987 735i No Spark, will not start

    I have an 84 733. The one problem I had with mine was the crank sensor
    located on the transmission. There are actually 2 sensors there one is the speed sensor the other is the position sensor. The problem I had was actually in the wireing. It was a real problem to find. I am still having problems from mine. You have to go back to the basics, Check for fuel and check for spark then proceed from there. It could be a fuel pump relay, or the main relay or the pressure regulator.
    Get a manuel. If you cant find one go to a good library; the might have one and xerox what you need. You will also need a digital vold/ohm meter and a lot of patience. Good Luck. Rick


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    Member No: 123311 JStein is an unknown quantity at this point JStein's Avatar
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    Is it runnig yet... ??? more

    If not... I second the suggestions to check the crank position reference sensor and speed sensor located on the left side lower bellhousing where it meets the engine( just below the starter.


    These sensors are a well known failure item and if they have neverbeen changed,.. you are well over due for failure.

    Lastly.... IMHO.. change them both.. yes it is a it more money all at once.. but if one is failed (and it will..) then the second will fail in the NEAR future and may leave you stranded along side a road and it may be in a location you'd find highly undesirable... ...

    Lastly here is the test ...

    eng speed sensor 960+/- 96 ohm between pins 8 & 27

    eng crank position ref sensor 960+/- 96 ohm between pins 25 & 26

    p/n=12 14 1 708 619


    But.. when replacing BOTH ... do them one at a time to avoid mixing up the connectors and locations....

    oh you don't want to go there.. btdt...it is ugly... js

    John Stein
    85 745 @ 1.2 bar
    85 M635CSi
    84 633

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