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  1. #1
    Join Date
    Jul 2007
    Location
    Posts
    365

    Default Oil pressure sensor bad?

    During the week I decided to do some "cleaning" up of my boat engine. Scrubbing this and that corrosion of sensors and what not. After cleaning up my oil pressure sensor switch connections I tried putting it back on and it seemed to not go back on like it should. The post the hex nut screws onto felt loose going back on.

    So today when I took the boat out it ran fine for a while then would not start. The fuse on the fuel pumps was tripped. I reset it and the boat ran again, for a while then it tripped again. It seems to reset when I wiggled the oil pressure sensor wire (blue wire).

    I'm thinking the ecm is not getting the signal it needs from the oil pressure switch and it's cutting the engine off because it thinks there is no oil in the engine.

    Sound plausible?
    1994
    5.7 GI-PMDA
    AQ DP-C

  2. #2
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    7,340

    Default Re: Oil pressure sensor bad?

    Sounds like you are thinking correctly, since this appears to be the only item that you messed with.
    The switch does sense oil pressure, which is designed to cut fuel pump power, should the engine quit running.
    Conversely, the switch must close, in order for the pump to continue operating once past the start-by-pass circuit.

    You may want to replace this switch.
    Try this page..... and go to FUEL SYSTEM & INTAKE MANIFOLD - 5.7 Gi


    The DP-C is a great drive, btw....... one of my favorites!

    It's a real shame that Volvo Penta steered away from the AQ series, and changed to a Gimbal System drive! A shot in the foot, IMO.

    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  3. #3
    Join Date
    Jul 2007
    Location
    Posts
    365

    Default Re: Oil pressure sensor bad?

    Quote Originally Posted by RicardoMarine View Post
    Sounds like you are thinking correctly, since this appears to be the only item that you messed with.
    ... that may not be entirely true. I also messed with other parts.

    It all started with changing the fuel filter.

    Then I noticed the engine coolant sensor seems a bit corroded. So I unscrewed the hex nut on the back of it and took all the washers off and used a wire brush to clean all connections.

    I did the same with the water temperature sensor. I replaced all my gauges and since the water temperature gauge doesn't work (it did before I changed the gauges) I decided to clean that out as well and check the wires while I was at it. The gauge still doesn't work after cleaning the connections. So I hooked up a multimeter to the wires coming from the water temperature sensor and checked for resistance; per the seloc manual. The readings I got were from about a few hundred to about six hundred or so. Which tells me the thermistor inside it is working and somewhere along the way to the gauge there is a broken connection. What I don't know is where the the two wires coming from the water temperature sensor go together to connect to the tan wire that goes to the gauge.

    Now to my previously mentioned oil pressure sensor; while trying to screw the hex nut back on after cleaning all the connections I noticed that the post the hex nut screws onto was a bit wobbly while trying to screw it back on. To me, it shouldn't have been wobbly, but it is.

    I have taken the boat out the last few weeks and everything worked fine, except for the gauges I mentioned above. So we go out this weekend and do three laps around the lake; about 20 minutes of running fine at ~ 3k rpm. No hiccups or any other noticeable issues. We stop to let people cool off and the boat wouldn't start. I took off the flame arrestor and noticed gas wasn't being injected. I pushed all the fuses in and noticed the fuel pump fuse was tripped and reset it. Bingo, fuel started flowing again and the boat started like normal. At least for about a minute or so then the engine died. After a few minutes I was able to reset the fuel pump fuse again and the same thing; the boat worked for about a minute and then it died. I had to repeat the process about five or six times to get to the dock.

    I hook up the ear muffs in the drive way today and the same thing happens, it ran for a little while (about a minute or so) and then it shuts off; the fuel pump fuse being tripped in the process somehow. One time it did run for about 5 or 6 minutes then back to square one. Some of the wires are a bit chaffed to be honest, but I don't see any of them grounding out, at least not the ones I messed with.

    And that's where I'm stuck now .....

    Several different issues I know. The gauges I'm not too worried about at the moment, the fuel pump fuse being tripped is my main concern. BTW, it was replaced just last year.
    1994
    5.7 GI-PMDA
    AQ DP-C

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