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Thread: Changed fuel pump now no gas 1998 740i

  1. #1
    Join Date
    Aug 2018
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    Cincinnati, Ohio
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    1998 BMW 740i

    Changed fuel pump now no gas 1998 740i

    Sorry if this is a repeat, but my 1998 740i had an instance where it ran like it was running out of fuel, and sputtering, but had 1/4 tank of gas. I put gas in it and all was good as before. I was driving it a few days ago with 3/4 tank, and it did the same. had it towed and replaced the fuel pump, put it back together and now it only cranks. the Fuse for the pump is good, the car is getting fire, but the pump isnt pumping. any help will be appreciated. thanks

  2. #2
    Join Date
    Feb 2009
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    KC North, MO, USA
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    1996 740iL
    If the pump does not start while the car is cranking, I would first use a multimeter to see if you are getting power and ground to the pump. The relay for the pump is above the battery, second from the right. If the pump is running when cranking, it could be the fuel filter which is located under the splash shield near the rear passenger door.

    The crank sensor sends the signal to the DME that the car is cranking. The DME then calls for fuel and spark, although I have heard reported others have had spark with a bad crank sensor.

  3. #3
    Join Date
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    1998 BMW 740i
    i used a multimeter set to volts and tested the plug for the pump and got zero reading, i also switched the relay with the one next to it, as both are the same blue and still nothing. and no fuel is being pumped
    Last edited by cnjames6; 08-12-2018 at 04:05 PM.

  4. #4
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    Did you test it while the car was cranking over? If so, I would suspect the crank sensor. Since you can use a meter, the crank sensor should read around 540 ohms. The crank sensor does not always throw a code. Do you have any codes by the way?
    Last edited by Mayorchuck; 08-13-2018 at 04:14 PM.

  5. #5
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    i did test with care cranking, if the cam sensor was going out, would that explain the randomly bogging down like it wasnt getting fuel? i do have a check engine light, but my code reader said no codes. does inpa work on this class of car?

  6. #6
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    Absolutely. Do you have the cable for the 20 pin under the hood?

  7. #7
    Join Date
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    99 840ci Sport Indv
    It is the CRANKshaft sensor that would be suspect - the pump still runs with no signal from the CAMshaft sensor.....
    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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  8. #8
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    Thanks Tim. Didn't even noticed I typed that. Corrected.

  9. #9
    Join Date
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    1998 BMW 740i
    sorry for the delayed response, you gentlemen have been great, it turns out my multi meter wasn't working proper, I bought another before buying any sensors, and found that i was actually getting power to the pump, turns out the "hot wire" wasn't connected well enough.

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