Fuel pressure issue
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Fuel pressure issue

  1. #1
    AKA OhOneWS6 Last Mohican's Avatar
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    Default Fuel pressure issue

    I've got a fuel pressure issue. It will run great for 10 - 15 minutes at 3200 or so then it just peters out. The fuel pressure falls completely off to 0. After is sits (get towed) for 10 - 15 minutes it will fire right back up and the fuel pressure will return to ~ 6 lbs. This is a mechanical fuel pump and a Q-Jet carb. It has a new water separator and all new rubber fuel lines. My gut feeling is there is sediment in the tank that gets suspended and after 10 minutes or so it manages to pack the sock on the tank pickup. Once the boat dies is sloshes around and the sediment falls off the pick up and it is fine again. Wash, Rinse, Repeat. It has done this pretty consistently on every long haul I have made with it. It does just fine if I stick to short runs

    In conversation with another boater at the lake this weekend he said he had the exact same issue and it was the same style water separator. He said he bypassed it with just a regular inline fuel filter and it resolved his issue. He said he fought it for a long time before finally getting it resolved.

    The tanks are tabbed in with glass and I don't think I can get the pickup out without removing the tank. The plan is to bypass the separator with a filter. If that does not fix it I am going to borrow a portable fuel cell from a friend and use that instead of the on board tank. If the borrowed tank fixes it I know I have an issue in my tank. If not it has to be the pump.

    Anyone have any other suggestions? I'm all ears.

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  3. #2
    Cheers for beers! DELTA~HOLIC's Avatar
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    Quote Originally Posted by Last Mohican View Post
    I've got a fuel pressure issue. It will run great for 10 - 15 minutes at 3200 or so then it just peters out. The fuel pressure falls completely off to 0. After is sits (get towed) for 10 - 15 minutes it will fire right back up and the fuel pressure will return to ~ 6 lbs. This is a mechanical fuel pump and a Q-Jet carb. It has a new water separator and all new rubber fuel lines. My gut feeling is there is sediment in the tank that gets suspended and after 10 minutes or so it manages to pack the sock on the tank pickup. Once the boat dies is sloshes around and the sediment falls off the pick up and it is fine again. Wash, Rinse, Repeat. It has done this pretty consistently on every long haul I have made with it. It does just fine if I stick to short runs

    In conversation with another boater at the lake this weekend he said he had the exact same issue and it was the same style water separator. He said he bypassed it with just a regular inline fuel filter and it resolved his issue. He said he fought it for a long time before finally getting it resolved.

    The tanks are tabbed in with glass and I don't think I can get the pickup out without removing the tank. The plan is to bypass the separator with a filter. If that does not fix it I am going to borrow a portable fuel cell from a friend and use that instead of the on board tank. If the borrowed tank fixes it I know I have an issue in my tank. If not it has to be the pump.

    Anyone have any other suggestions? I'm all ears.
    I had this exact same issue! where the connector hooks up to the fuel line by the pickup was clogged/broken. It was a stock connector with an anti siphon valve so the fuel didnt leak back into the tank. Check that connector and if it has that anti siphon valve ditch it. Also when I took out my tank, I found nut bolts, gas cap chain, all kinds of crap. The tank was a bow tank that was burried in foam. It was a bitch to take out!



  4. #3
    AKA OhOneWS6 Last Mohican's Avatar
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    Quote Originally Posted by DELTA~HOLIC View Post
    I had this exact same issue! where the connector hooks up to the fuel line by the pickup was clogged/broken. It was a stock connector with an anti siphon valve so the fuel didnt leak back into the tank. Check that connector and if it has that anti siphon valve ditch it. Also when I took out my tank, I found nut bolts, gas cap chain, all kinds of crap. The tank was a bow tank that was burried in foam. It was a bitch to take out!
    I had someone else suggest that at the lake. Can you tell by looking at the fitting if there is a valve or do you have to just take it apart and look for the ball inside the fitting?

  5. #4
    Cheers for beers! DELTA~HOLIC's Avatar
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    Quote Originally Posted by Last Mohican View Post
    I had someone else suggest that at the lake. Can you tell by looking at the fitting if there is a valve or do you have to just take it apart and look for the ball inside the fitting?
    just looked like a regular 90* fitting. once removed you can see the ball inside. I tried blowing in it and could definately feel the restriction. It was clogged up with my deteriorating fuel float. I would be able to drive the boat for about 15 mins, then slowly watch the fuel pressure drop until the engine died. then wait another 15 mins and would fire back up again.



  6. #5
    "Need For Speed" Gearhead's Avatar
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    You may also want to check your fuel tank venting system. If the vent is plugged, it may take a number of seconds but then the pump will pull a vacuum and stop. Dirt dobbers etc. You can test this by running with the fuel cap loose.

    Just another thing to check.

    Gearhead

  7. #6
    AKA OhOneWS6 Last Mohican's Avatar
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    Quote Originally Posted by Gearhead View Post
    You may also want to check your fuel tank venting system. If the vent is plugged, it may take a number of seconds but then the pump will pull a vacuum and stop. Dirt dobbers etc. You can test this by running with the fuel cap loose.

    Just another thing to check.

    Gearhead
    Tried running with the cap open and no difference. Delta may be on to something. The fuel level gauge for that side does not work.

    Thanks for all the suggestions. Please keep them coming. The more things I have to check next timeout the better my chance of getting it fixed.

  8. #7
    Boat Nut sleekcrafter's Avatar
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    I was able to remove the tank fittings on my 23' sleek, replaced the pick ups and cleaned the screens.
    Upper Midwest Power Boat Association
    DRAG BOAT RACING UMPBA #926


  9. #8
    Senior Member YumaJet's Avatar
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    I just use -8 lines with a russell fuel filter to my mech fuel pump.

    Compared to when I used a fuel/water separater, 3/8 lines, fuel filter, restrictors; it was night and day. Its always a pain in the but when it would get clogged.
    boatless....

  10. #9
    AKA OhOneWS6 Last Mohican's Avatar
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    Quote Originally Posted by sleekcrafter View Post
    I was able to remove the tank fittings on my 23' sleek, replaced the pick ups and cleaned the screens.
    What year is your Sleek? Were the pickups flexible plastic or hard metal?

  11. #10
    AKA OhOneWS6 Last Mohican's Avatar
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    I believe I have found my issue with the fuel system. It is the water separator. I pulled the fuel line back off at the tank selection valve. I pulled the other end off the fuel pump. I then blew from the valve to the pump through the separator. I could blow through it but I could tell there was some restriction. I then bypassed the separator and installed just a regular inline filter. With my calibrated lung I could tell it was much easier to blow through. Just to double check I put a short piece of fuel line on the separator and blew through it with no other devices or line hooked up. This time by the degree of light headedness I got, I could tell it is certainly restrictive. Still need to lake test it but I am pretty sure this is the issue.

    The suspected culprit.

  12. #11
    Member gublube's Avatar
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    i had same prob with my 454,build up to 7lbs drop to 0 in few min.i took the feul pump off,its a holly and it was clogged with crud.i cleaned it and ran fine,did it again and same prob,i added some additive to clean old feul and gunk build up,added inline filters and havent had the problem since.its a electric feul pump.has a little screen inside it.just a suggestion.

    john
    Last edited by gublube; 09-18-2010 at 03:30 PM.

  13. #12
    AKA OhOneWS6 Last Mohican's Avatar
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    This one has a mechanical pump. I have checked every component individually. From the tank pickup tube all the way to the carb inlet. The only restriction I can identify is this water separator. I talked to another boater at the lake on Labor day. He said he had the exact same issue and it was the separator. I am pretty confident this is the issue. We'll see next time out.

  14. #13
    AKA OhOneWS6 Last Mohican's Avatar
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    Fuel pressure issue is fixed!!!! Made a run across the lake and back non stop yesterday evening. The fuel pressure never fell below 5 lbs. The water separator was definitely the issue.

  15. #14
    Senior Member Rain Maker MN's Avatar
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    Somtimes drawing from two tanks at the same time can be an issue, and some people run a fuel tank selector to only draw from one...

    Glad to hear it was fixed

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