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  1. #1
    Join Date
    Aug 2011
    Location
    San Diego, CA
    Posts
    9

    Default 5.0 Mercruiser Fuel Pump wont shut off

    Hello there, I have a 2001 5.0 Mercruiser 305. I was cleaning out the bilge under the engine yesterday and some water splashed up on the engine area. The fuel pump turned on and will not shut off now even with the key in the off position.

    I did some research about this problem and most of the time it is due to the relay. Tapping it, resetting or replacing usually does the trick. The problem is I can't find the relay and am not sure that my motor has one. I looked up with parts catalog with the motor serial number(0M079776) and couldn't find a relay part listed.

    Maybe I'm overlooking something(like finding the relay) or it doesn't have one? Any guidance on locating it or an alternate solution without having to replace the pump would be much appreciated!

    Thanks,

    Todd

  2. #2
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    5,145

    Default Re: 5.0 Mercruiser Fuel Pump wont shut off

    Quote Originally Posted by Todd Sabo View Post
    Hello there, I have a 2001 5.0 Mercruiser 305. I was cleaning out the bilge under the engine yesterday and some water splashed up on the engine area. The fuel pump turned on and will not shut off now even with the key in the off position.

    I did some research about this problem and most of the time it is due to the relay. Tapping it, resetting or replacing usually does the trick. The problem is I can't find the relay and am not sure that my motor has one. I looked up with parts catalog with the motor serial number(0M079776) and couldn't find a relay part listed.

    Maybe I'm overlooking something(like finding the relay) or it doesn't have one? Any guidance on locating it or an alternate solution without having to replace the pump would be much appreciated!

    Thanks,

    Todd
    Ayuh,..... Carbed,..?? Efi,..?? Mpi,..??
    Any Grease is Better,... Than No grease at All....

  3. #3
    Join Date
    Aug 2011
    Location
    San Diego, CA
    Posts
    9

    Default Re: 5.0 Mercruiser Fuel Pump wont shut off

    Quote Originally Posted by bondo View Post
    Ayuh,..... Carbed,..?? Efi,..?? Mpi,..??

    Sorry, It's Carb, and so I found out there's no relay. I've disconnected the pump from the battery, so it doesn't run. The engine starts up and runs fine(when I reconnect the pump), however when I turn the key off the motor doesn't shut off. I have to try starting it again(grinding the starter) while the motor is running and then turning the key to the off position for the engine to turn off.

    The fuel pump also makes a whining noise...not sure if that's normal as I didn't notice it before.

    Thanks,

    Todd

  4. #4
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    4,793

    Default Re: 5.0 Mercruiser Fuel Pump wont shut off

    Here is your schematic..


    Sounds fishy to me.......

  5. #5
    Join Date
    Aug 2011
    Location
    San Diego, CA
    Posts
    9

    Default Re: 5.0 Mercruiser Fuel Pump wont shut off

    Quote Originally Posted by kghost View Post
    Here is your schematic..


    Sounds fishy to me.......

    Thanks, I already found the schematic. I agree. Any suggestions?

  6. #6
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    5,145

    Default Re: 5.0 Mercruiser Fuel Pump wont shut off

    Quote Originally Posted by Todd Sabo View Post
    Thanks, I already found the schematic. I agree. Any suggestions?
    Ayuh,... The fuel pump can get power from only 2 places,...

    We can't see yer boat, so YOU'VE gotta Look...

    Bring yer Test Light....
    Any Grease is Better,... Than No grease at All....

  7. #7
    Join Date
    Aug 2006
    Location
    SW Ohio, USA
    Posts
    10,396

    Default Re: 5.0 Mercruiser Fuel Pump wont shut off

    however when I turn the key off the motor doesn't shut off.
    Look for a short around the starter...you must have bumped a loose wire or some conductive debris was splashed on the wire connections.
    Fix minor things (replace wear items for preventative maintenance.) that cause major problems before they break.

  8. #8
    Join Date
    Aug 2011
    Location
    San Diego, CA
    Posts
    9

    Default Re: 5.0 Mercruiser Fuel Pump wont shut off

    Quote Originally Posted by guyjg View Post
    Look for a short around the starter...you must have bumped a loose wire or some conductive debris was splashed on the wire connections.

    I found it and giyig was correct. It was a loose wire around the starter that was causing the short. Thanks all for the contributions.

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