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Thread: fuel pump issue

  1. #1

    Default fuel pump issue

    hello- have an intermittent issue with fuel pump on 1997 7.4l 454 crusader- when I go to prime mode after boat sitting for a week
    in the slip- I put shftlever forward and turn key t crank to prime carb - sometimes pump does not run - I have tested 13.09 volts
    at the pump . If I jump the pump from battery directly goes on - then works fine all weekend - I just replaced relay and 10 amp
    push button breaker but same issue. any ideas? thanks in advance-cruiser

  2. #2
    Join Date
    Sep 2008
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    Maryland - USA
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    Default Re: fuel pump issue

    if the pump is original, I'd suspect its at the end of life.....20 years ain't back.....

    only other thing to check would be to ensure the pump has a good ground....

  3. #3

    Default Re: fuel pump issue

    the pump is about 3 yrs old - I replaced due to same issue - just been dealing with it - it seems that the pump looses prime and will not
    initially prime unless I jump it directly- then it works fine - marina tells me has voltage but not enough amps ?????

  4. #4

    Default Re: fuel pump issue

    If insufficient amps is the problem, might be high resistance in the oil pressure switch. Worth investigating.

    FL Panhandle

  5. #5
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    Default Re: fuel pump issue

    If the pump is on the engine, it should be self priming....

    is the pump not running (or not starting) or running and not delivering fuel?

    you need to check BOTH sides of the pump's electrical feed as a resistance in either side will inhibit proper operation....

    what was going on when you measured the 13.09 VDC and how was the meter hooked up?

  6. #6

    Default Re: fuel pump issue

    the pump reads 13.09 volts at the pump connection when in the priming sequence per the manual- shifter forward so no engine
    crank- then turn key to crank position till carb primes- my port engine no issues-- just the starboard- the electr pump is on a
    bracket mounted on engine- meter was hooked up as follow- red to the purple red at pump connector and black lead to the
    engine ground- how do I check resistance ? Cruiser1

    /

  7. #7
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    Default Re: fuel pump issue

    It's hard get do resistance, directly....better and easier to make voltage drop measurements.

    I'd suggest, at the next opportunity, to repeat what you did before, with these two additions - and by only moving the RED lead: battery voltage (at the battery's + terminal) and the ground side of the fuel pump. That will give you insight into the wiring for the fuel pump....

  8. #8
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
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    3,808

    Default Re: fuel pump issue

    considering that shifting the control box into gear activates the "no start in gear" feature turning the key to "crank" will do nothing to energize a fuel pump.
    You could install a priming button at the dash or a priming button in the engine compartment.

  9. #9

    Default Re: fuel pump issue

    While cranking, the starter circuit actually energizes the electric fuel pump. With the trans in gear the neutral safety switch prevents the starter from running but still allows the fuel pump to run. Once the engine starts, the pressure switch directs line voltage to the pump. Is true !!

  10. #10
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    Sep 2008
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    Default Re: fuel pump issue

    Mullet - do you have the wiring diagram for your engines?.....I know there are many of you that have this 'primer' feature but there's nothing I have in the little bit of factory data I have that shows how its done. The later diagrams I have (2003 ? and newer) show this "feature" isn't supported....thanks..

  11. #11

    Default Re: fuel pump issue

    Mako,
    I have the wiring diagram for carbed XLs which only shows the standard “pump activated while cranking”system. Would not recommend it, but the system can be modified to a “switched pump activation/prime” system. If doing so it would be necessary to disable the standard system to safely avoid possible feedback that would inadvertently engage the starter while priming. The basic system could be preserved is using a diode in the starter circuit, but that would be pretty sophisticated and may lack reliability. The mod would consist of cutting the yellow/red wire at the pressure switch and directing switched (springloaded button) voltage directly to the pump. I prefer the “trans in gear – starter switch on” method to precharge thecarbs. Except for the ringing alarm bell, it works just fine.
    FL Panhandle

  12. #12
    Join Date
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    Default Re: fuel pump issue

    Mullet - I asked as I've never seen it.....all of the diagrams I have show 'pump active when cranking'. That said, there have been numerous owner's that have posted they have the ability to prime while cranking in gear....so I figured I'd ask.

    There are many ways to mod the circuit to enable a prime function....properly rated diodes aren't a reliability issue but there installation may be. Just curious how the factory enabled that function while limiting the documentation....

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