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05' 150 4 stroke. 125hrs. Fuel Issues.

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  • 05' 150 4 stroke. 125hrs. Fuel Issues.

    Greetings!

    Short history. Motor has 125hrs. I've put ~90 of those on it. I've turned wrenches for going on 30+ years now. Not a rookie, but not real familiar with Outboards.

    Did the 100hr service. (I got a base line @ 50hrs and started changing fuel filters every 25hrs.) Ran like it always has. (everytime I fuel the boat, I treat the fuel). This last trip about 6 weeks ago, I noticed it falling on its face on the top end and WOT. No big deal - maybe water got past the filter, I'll clean her up good and service it again, even though I had just did it.

    Up until this point I've never paid attention to the fuel level in the filter located at the front of the motor (small cartridge filter with the plastic water level ring on it). However, after changing it this time and heat cycling the engine, I discover that the canister does not stay full. In fact, when @ idle, it will drop down to the lower part of the pleats on the cartridge.

    My gut tells me fuel pressure should keep that canister full - as it will need proper volume and pressure to feed WOT or top end demands.

    Is that a fair statement? Am I on the right track diagnosing my issue with starving for fuel @ WOT? (I did replace the primer bulb and fuel line with it thinking that over time the wall of the line is failing, although I didn't see evidence of that in the cartridge).

    Sorry for the long wind here - I'm going to put it in the water in the morning and see where I'm at. Next step if it continues is to purchase a fuel test gauge. Not sure the kit I have for the Automotive industry will fit it.

  • #2
    The gentleman on here will want the full identity information on the ID tag on the transom bracket. They can help you better with this information.

    Thanks

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    • #3
      Thanks for the information. I will have that in the morning.

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      • #4
        Are you using E10?
        how big is the tank and how full do you keep it?' how much to you run it/how old is the fuel i the tank right now?

        monitoring pressure while problem shows up will help

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        • #5
          Originally posted by Redwards View Post
          I discover that the canister does not stay full. In fact, when @ idle, it will drop down to the lower part of the pleats on the cartridge.

          My gut tells me fuel pressure should keep that canister full - as it will need proper volume and pressure to feed WOT or top end demands.

          Is that a fair statement? Am I on the right track diagnosing my issue with starving for fuel @ WOT?
          no.
          It is normal for fuel level in that "canister" ("sediment bowl") to be visibly "not full" - and to fluctuate.
          (I don't understand why, either - something about the way fuel gets "pulled" up through the inside of the paper element)

          Your engine is actually "running" on the fuel in it's own "miniature fuel tank": the VST

          The VST has a float & needle valve, just like a carburetor -
          and its the job of the mechanical fuel pump to keep the VST "topped up"

          Your primer bulb is very handy to diagnose if your pump is not keeping the VST full -
          when its :"falling on its face", squeeze the primer and see if that corrects the problem.
          If "adding fuel" with the primer solves the issue - then the problem is with the supply to the VST.
          If there is no change - if no fuel can be pumped with the primer bulb -
          then the issue is within the VST - or the injectors.


          You should definitely be able to plumb in your regular automobile gauge
          and measure the mechanical fuel gauge performance -

          ideally little to no vacuum on the suction side
          I'm guessing: 5-10 psi on the pressure side

          Attaching a fuel injection pressure gauge (~40 psi) to the fuel rail is of course also diagnostic
          Last edited by fairdeal; 04-30-2017, 09:05 AM.

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          • #6
            I have the same motor. Top level of fuel barely touches the filter media when running.

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