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Thread: No fuel pump pressure 735i -SOLVED, defective fusible link, with pics

  1. #1
    Join Date
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    '89 535i/5, '88 735i/5

    No fuel pump pressure 735i -SOLVED, defective fusible link, with pics

    I'm having a weird issue with the shitbox e32 I have.

    I drove it across the street this morning no problems, but now it won't fire up.

    Im getting zero fuel pressure. The pump isn't turning on at all.

    Things I've done to try and troubleshoot so far:
    -Replaced fuel pump fuse
    -replaced fuel pump relay with known good one
    -replaced main power relay next to fuel relay
    -swapped DMEs
    -swapped fuel pump
    -jumpered the fuel pump relay
    -checked power at pin #13 on main engine harness (no indication)
    -swapped cps
    -put gas in the tank

    The only thing I can think is a broken wire somewhere. The original main power relay was looking a little melted.

    Anyone else have any experience with this? I'm quite frustrated

  2. #2
    Join Date
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    '89 535i/5, '88 735i/5
    Ok I finally found my multimeter and tested all the relay connections, and I'm getting 12v at them.

    I'm also getting continuity on the ground wire on the plug for the fuel pump, and 11.5 volts power.

    So it looks like it's a dead fuel pump, but it still does it when I swap it out with a known good one.

    I'm at a loss. I have no idea at this point

    Sent from my SM-G900V using Tapatalk

  3. #3
    Join Date
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    '89 535i/5, '88 735i/5
    And I just tested the fuel pump with a battery and its working.

    Still at a loss

    Sent from my SM-G900V using Tapatalk

  4. #4
    Join Date
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    11/88 E32 750iL+98 E36M3
    Did you check both fusible links next to the battery? See my website where they are under reference data>>electrical
    X6400 is the power post inside the E box. It feeds only DME loads.Fusible link A ist in the heat shrink on the cable from battery to front
    Shogun tricks and tips for the E32 series are HERE!

  5. #5
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    Yes. Fusible link is good.

    Sent from my SM-G900V using Tapatalk

  6. #6
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    Update: I don't know what I'm doing with my life.

    Had power at the pump. Now nothing.

    Had power at the fusebox, now nothing.

    Still got power at the relay and the the wire leading to the fusebox immediately after the relay.

    What the shit

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  7. #7
    Join Date
    May 2012
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    Boynton Beach, Florida
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    My Cars
    1990 735I (E32) M30
    Yesterday you said that the Main Relay was melted. I'm guessing by main relay you mean the white relay not in the fuse box, but in the box with the computer on the passenger side near the firewall? Did you replace that? So many "no start" problems have been solved with that replacement.
    1990 735I (Auto) E32 Feb 1990 to Present
    1996 Z3 Roadster (5 Speed) E36/7 Jan 1999 to Dec 1999
    1983 733I (5 Speed) E23 April 1983 to Feb 1990
    https://www.youtube.com/watch?v=2d4tHoHGaJo
    https://1drv.ms/v/s!Av20xCMMocSsyEpl...h_oOk?e=ekIcAT







  8. #8
    Join Date
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    to make it easier, all relays , where they are and for what and by built year and engine http://www.e32-schrauber.de/bmw/s-relaisbelegung.htm
    on the E32 735 it is shown here
    http://bmwe32.masscom.net/johan/e_box/fuse_box.html

    I also assume there is something melted in the wiring
    Shogun tricks and tips for the E32 series are HERE!

  9. #9
    Join Date
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    Ok I'm an idiot. I didn't realize there was another fusible link back there.

    It had broken and was intermittently making contact and giving power to the relay.

    I've swapped it out with a proper replaceable in line fuse with the proper amperage.


  10. #10
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    And I also wrapped the exposed hardware with f4 tape to ensure it won't short out on the chassis.

    Sent from my SM-G900V using Tapatalk

  11. #11
    Join Date
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    11/88 E32 750iL+98 E36M3
    And another no start problem solved with no start due to the fusible links, he also found first only one on his E31, https://www.bimmerforums.com/forum/s...-fusible-links
    Shogun tricks and tips for the E32 series are HERE!

  12. #12
    Join Date
    Sep 2018
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    Lake worth
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    E32
    Where is the fusible link in the back?? I'm having the same problem, only the fuel pump fuse is not getting power? Everything else gets power all the fuses and relays just not the fuel pump fuse. Help!

  13. #13
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    close to the battery under rear seat, here are pics of the 2 fusible links, the first 2 pics are for the inline fuse which goes to engine bay to B+ and the e-box http://www.bimmerboard.com/forums/posts/377728/

    My Cars E32
    please add more details like 735i/iL and the month and year of production, helps us to help you
    Last edited by shogun; 09-06-2018 at 09:37 AM.
    Shogun tricks and tips for the E32 series are HERE!

  14. #14
    Join Date
    Sep 2018
    Location
    Colorado
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    My Cars
    1993 BMW 740i E32
    When you replace the fusible link, do you reattach with nuts and bolts? I am a novice when it comes to BMW's. This past weekend was the first time I have ever touched one.

  15. #15
    Join Date
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    Nuts and bolts if fine. From your PM I understand you have the following problem: 1993 740i E32, yr Fiance's car stopped running a few days ago. Thought it was a fuel issue. replaced fuel pump and relay. That did not help. All it will do is crank. Shot Ether and got a split second "lub-dub" but that was all. Any and all help you could offer would be much appreciated!

    After the fuel pump replacement, is the fuel line under pressure in engine bay?
    Here some more tests http://www.bimmerboard.com/forums/posts/1259287/
    wiring diagrams, fuse box and relay layout is here http://shark.armchair.mb.ca/~dave/BMW/e32/

    Test the crankshaft position sensor, if that is dead, no fuel, 540ohm +/- 10%, see here https://wiki.bentleypublishers.com/d...specifications
    Last edited by shogun; 09-10-2018 at 09:29 PM.
    Shogun tricks and tips for the E32 series are HERE!

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