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  1. #1

    Default Mercruiser 5.7 electronic fuel pump not getting power

    Own a 1998 Baja with 5.7 L carburated Mercruiser. Put the boat away after july 4th weekend and was running fine. Got back to the lake this weekend and won't start. Pumping throttle used to work for starting after long periods of no use, but did not smell any gas at all, so put a thimble full of gas in carb and it fired right up then died. Engine still would not even attempt to start without putting gas directly in carb.

    Boat has 3/4 tank of gas, and lanyard is firmly set in place.

    After trouble shooting fuses (all I can find under dash are good) took out fuel pump and connected directly to a battery it pumps. But connected to engine wiring harness does not run. I canot find any fuses or relays in the engine compartment to check.

    I don't have any service manuals.

    I think totally unrelated, but tach stopped working 6 months ago, but engine has been extremely reliable until this weekend.

    Any ideas anyone can provide to trouble shoot would be appreciated. I'm in Pittsburgh, while boat hangs in my dock slip at Smith Mountain Lake, so won't be able to test anyones ideas for 2 weeks

  2. #2
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Mercruiser 5.7 electronic fuel pump not getting power

    Check the connections on the oil pressure switch. Sounds like they are corroded or disconnected. If it would start and not stay running for more than 15 to 20 seconds then I would think bad oil pressure switch. Could also be the connector that attaches dirctly to the pump. Do some voltage checks.

    PS, here is a link to the manual if you actually have a 1998 engine. What is your Merc SN?

    http://www-alt.mercurymarine.com/mne...24/24covr1.pdf
    Don S.


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  3. #3

    Default Re: Mercruiser 5.7 electronic fuel pump not getting power

    Thanks Don, I'll give it a try. The serial number OL065539. Thank you for the link to manual, I was trying to decide if SOLEC online was worth 35 bucks. Hopefully I'll have some luck with your idea. I don't think it is an issue with the fuel pump wiring itself as I jumped from battery to the fuel pump male wiring connection and it worked, it just does not run with the key on and plugged into the harness.

    I did find 2 black wires uncnnected, but they look as though they are extra wires that have never been connected (on on back right and one on top left) sorry I can't be more specific.

  4. #4
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Mercruiser 5.7 electronic fuel pump not getting power

    The serial number OL065539
    The link I gave you is the correct manual. Look at ALL the wiring for the fuel pump system in the wiring diagrams.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
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  5. #5

    Default Re: Mercruiser 5.7 electronic fuel pump not getting power

    Thanks Don, I'll give it a try. The serial number OL065539. Thank you for the link to manual, I was trying to decide if SOLEC online was worth 35 bucks. Hopefully I'll have some luck with your idea. I don't think it is an issue with the fuel pump wiring itself as I jumped from battery to the fuel pump male wiring connection and it worked, it just does not run with the key on and plugged into the harness.

    I did find 2 black wires uncnnected, but they look as though they are extra wires that have never been connected (on on back right and one on top left) sorry I can't be more specific.

  6. #6
    Cadet
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    Question Re: Mercruiser 5.7 electronic fuel pump not getting power

    [QUOTE=Don S;1812274]Check the connections on the oil pressure switch. Sounds like they are corroded or disconnected. If it would start and not stay running for more than 15 to 20 seconds then I would think bad oil pressure switch. Could also be the connector that attaches dirctly to the pump. Do some voltage checks.

    Have same issue on my port side engine. Have had the issue for about 2 months. I previously planned on doing several maintenance items on this 12 year old boat before this issue and they have been done, the problem was unaffected by these changes.

    5.7 mercruiser alpha 2bbl carburetor. Serial no: 0L018151

    New components on both engines: cap, rotor, wires, plugs, ignition coils, distributor sensor (internal), oil pressure switches (for fuel pump-Mercruiser #864252A01), water temp sender (gauge), batteries, and the key-ignition switch.
    Port engine starts and runs about 10 seconds shuts down.
    1. Verified there is no power to the fuel pump, replaced the oil pressure switch again just to eliminate possibility of defective switch, no change
    2. Checked power to the switch, do not have power on either wire even when key is turned on.
    3. When I supply power to the pump, it runs awesome.
    4. When cranking the engine oil pressure is good, and when running is perfect.
    5. When key is held to crank position, starter engaged the engine will stay running and throttle does respond, second you let go, engine dies.
    I know a wiring problem could exist but was wondering if any ideas before I start tearing the harness apart?

  7. #7
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    Default Re: Mercruiser 5.7 electronic fuel pump not getting power

    Quote Originally Posted by Mac@Pitt View Post
    Thanks Don, I'll give it a try. The serial number OL065539. Thank you for the link to manual, I was trying to decide if SOLEC online was worth 35 bucks. Hopefully I'll have some luck with your idea. I don't think it is an issue with the fuel pump wiring itself as I jumped from battery to the fuel pump male wiring connection and it worked, it just does not run with the key on and plugged into the harness.

    I did find 2 black wires uncnnected, but they look as though they are extra wires that have never been connected (on on back right and one on top left) sorry I can't be more specific.
    I have the same problem with my port engine, what did actually resolve the issue.?

  8. #8
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Mercruiser 5.7 electronic fuel pump not getting power

    You need to start a new thread with your questions vetteman, not just hijack someone elses thread from 2008.

    http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/announcements.html
    Don S.


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    That is what the forums are for.
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  9. #9
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    Default Re: Mercruiser 5.7 electronic fuel pump not getting power

    Sorry, Have never done this before. Will try

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