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Thread: Letting the smoke out (pump)

  1. #1
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    Letting the smoke out (pump)

    Finally got my fuel pump out (after spilling quite a bit of gas all over the garage floor and top of the fuel tank). When I apply 12V to the pump contacts, the black wire terminal immediately starts smoking, looks like it's melting the insulation. No pumping sounds at all. I didn't try to switch polarity on the power source because I didn't want further damage - negative pole on the battery was sending to the black wire. Is the pump completely toast? Salvageable with some seafoam? I'm just testing it wrong?



  2. #2
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    I can't help you with the wiring but if you are using the right polarity and pump is not running then its probably seized. Seems like it would run either direction if current is reversed or not. I would probably buy a can or two of Seafoam at wallyworld, pull off filter, and let pump stand in fluid for several days and see if it frees up.

    And, pump should not be run 'dry' from what others have mentioned on here.

  3. #3
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    Pump is dead. I have a new one left over, sent you a PM.

  4. #4
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    I just gained more appreciation for LHM,) Your carrier looks to be in good shape.
    Last edited by 8eights; 03-13-2018 at 11:51 PM.

  5. #5
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    1. Do NOT run the pump when it isn't submerged in gas. NO NO NO. Never.
    2. Replace pump. (see #1)
    3. If that pump ever was any good, it most assuredly isn't now... hence the smoke.
    4. Replace pump. (see #1)
    5. Did I mention not to dry run the pump? Not Ever.
    '91 Dinan 860 Stage III (soon to be Dinan TT 6L)
    '91 850i 6sp (mint)
    '91 850i 6sp (getting there)
    '90 Dinan 750iL TT stage III
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    '96 850Ci, The George Carlin car
    '94 840ci (4 short - obvious parts car), '91 850i parts car
    '73 3.0 csi, '08 535i, '95 318i
    ...and a few other non BMW cars

  6. #6
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    Anything special for a wire submerged in gasoline? Or can I just use regular wire that I already have for other purposes?

    What's LHM, 8eights?

    Also, what is so special about this pump that even a second or two of dry running would be so detrimental. I think it was dead already, and was trying to test to see if it even spun... What happens if you run out of gas? Won't the pump continue to run dry at that point?

    Quote Originally Posted by CDO5OO1A View Post
    <-- What he said. AND wire will NEED to be re-terminated and the end of the wire that got hot cut off. Once copper gets that hot it loses a percentage of its conductive properties.

    At least the first inch looks toasted.

    The filter at the bottom looks like it might be split too.

  7. #7
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    Quote Originally Posted by Spandrel View Post
    Anything special for a wire submerged in gasoline? Or can I just use regular wire that I already have for other purposes?

    What's LHM, 8eights?

    Also, what is so special about this pump that even a second or two of dry running would be so detrimental. I think it was dead already, and was trying to test to see if it even spun... What happens if you run out of gas? Won't the pump continue to run dry at that point?
    You can use regular wire. Running a pump dry usually damages the pump or shortens it's life span.

  8. #8
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    I'd use a couple of layers of quality heatshrink to rehab the oem wire if it were me. Way better than a splice. Hot or not, that wire is more than healthy enough to run the pump

    When you run out of gas, there is still enough gas in the pump for lubrication, it won't spit it all up the tube when it stops coming in. No dry pump runs, please
    LHM = Limp Home Mode, or running on 6 cylinders by design
    Last edited by cartoonz; 03-15-2018 at 11:39 AM.
    '91 Dinan 860 Stage III (soon to be Dinan TT 6L)
    '91 850i 6sp (mint)
    '91 850i 6sp (getting there)
    '90 Dinan 750iL TT stage III
    '94 850 CSi (being restored to factory perfect)
    '96 850Ci, The George Carlin car
    '94 840ci (4 short - obvious parts car), '91 850i parts car
    '73 3.0 csi, '08 535i, '95 318i
    ...and a few other non BMW cars

  9. #9
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    Quote Originally Posted by Spandrel View Post

    What's LHM, 8eights?
    As Cartoonz mentioned, The ability to drive the car with a dead fuel pump because 2 pumps are available, 1 per each bank for V12's So you can still crawl to safety and further with half a engine.

  10. #10
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    Thanks, Ed. New one is not an exact replacement as it doesn't have the retainment ridge below the top to secure it in the carrier - zip ties will suffice, I hope. Made a guess at polarity that the larger screw was negative in the same way the larger screw on the original unit was negative. Also had to repair one of the rubber dampers (zip tie again - through both remaining rubber parts to maintain function). Ended up splicing the negaitive wire that was smoking using an inline splice, solder and some heat shrink tubing. Looks ok. About to install and find out if it works.





    Quote Originally Posted by dragon850 View Post
    Pump is dead. I have a new one left over, sent you a PM.

  11. #11
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    Well, did it fire up? That install should be good enough..

  12. #12
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    It did!!!! Three and a half years in the middle of my garage and it moves under its own power!

    (No power steering, battery light and trans fail safe (still needs fluid after 8 liters in. Don't understand that one), but I'll take the progress!)

    Quote Originally Posted by dragon850 View Post
    Well, did it fire up? That install should be good enough..

  13. #13
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    Quote Originally Posted by Spandrel View Post
    It did!!!! Three and a half years in the middle of my garage and it moves under its own power!

    (No power steering, battery light and trans fail safe (still needs fluid after 8 liters in. Don't understand that one), but I'll take the progress!)
    Nice!! Good to hear!

    Sent from my SM-G892U using Tapatalk

  14. #14
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    About time too!
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  15. #15
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    Congrats on the progress...we all know the feeling too well. As Timm would say, "time for a cup of tea".

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