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01 sx225txrz gotta gremlin please help

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  • 01 sx225txrz gotta gremlin please help

    I have a 2001 225 ox66 saltwater series 2. The problems with this engine get worse and worse. Boat ran fine last summer except for a rough idle. Cleaned the o2 sensor and that fixed that problem. Took boat out to shake it down this year and it ran pretty good. Took it out the second time and it ran ok but had a little miss at wot. Thought I had stale fuel so I ran it around all day to use the fuel up. The third time I took the boat out it was hard to start but once it cranked it idled fine and started every time. This is when it got bad. The engine will not go over 1800 rpms with a load. You can baby it on a plane and if you even touch the trim button it will bogg until you let off the button. I immediately put it on the trailer. Drained the rest of the fuel. Added new fuel put two new priming bulbs and changed both filters, water sep and the filter on the engine. No change at all. Took the boat home and got on the forums. Then I pulled the vst tank and cleaned the screen which was not that dirty in my opinion. Cleaned the fuel pressure regulator screen. Checked the check valve. Replaced all three lp pumps. Fuel rail pressure is 36-38 psi. Took the boat out. No change. Another thing I noticed is when keys witch power is on the hp pump runs constantly. It will not shut off like it used to. It shut off once after running for a while and kinda sputtered up and down then came back on now it runs all the time. I feel like this is my problem. I have read and troubleshot and I know that the Ecu is not breaking the ground to the pump. The resistor checks out ok. There is constant 12v at the pump and constant ground. What could be telling the ECM to make this ground all of the time? One more thing I noticed was the plugs are covered in fuel and oil. It's smoking like crazy. I installed new plugs of course with the rest of the maintenance I did.. Help on this topic would be greatly appreciated. I've talked with some yammy techs and they said they've never seen this. I'm scratching my head and I know I can fix it but I'm kinda stumped. Need some direction.

  • #2
    couple tips.

    one is "bogs whrn I hit the trim switch".
    two is all 6 plugs are wet.

    mmmmmmm hit the trim switch and the engine bogs, what could possibly cause this?

    how about that DC motor just sucked all the avalible current from the ECU.

    running wet plugs.
    one of the functions of the ECU if it senses low battery voltage?
    it increases injector ON time to compensate for a slower pump.
    why test the pump resistor, its not used above about 1200 RPM.

    all that resistor does is drop pump operating voltage at low speeds.
    saves wear and tear on thbe pump and keeps fuel temperature cooler.

    I would carefully test amm my ground,battery and ECU connector to grounds.


    • #3
      I see you found Rodbolt, good deal.

      hopefully he will come back and also comment on whether the fuel pump is suppose to run all the time or shut off like you said yours use to but does not now


      • #4

        I had the samething happen to my 2000 250ox66. I tried cleaning CO2 sensor. No good , couldn't trouble shoot it. Then I said screw it and just bought a new Co2 sensor. Boat is running as good as new. Make sure you buy a new gasket
        If you haven't changed the VST filter change it.


        • #5
          it is not CO2 it is O2, but I am sure you know that


          • #6
            that O2 senbsor is close to 300 bucks.
            takes 10 min to test it and 8 min of that is letting the engine warm up.

            test compression and spark, then fix the issue.


            • #7
              Sorry it took so long. I never recieved an email saying anyone had responded. Still having the same issue. I have 115 psi on every cylinder. I'm getting fire. I connected a breakout harness and a seperate battery and cables. Cleaned the whole fuel system and changed every filter. I recently took it to a yamaha dealer and they are having problems figuring it out as well. I have changed coils and ECM with some spares I had. The engine will rev in gear if you trim the prop out of the water. It seems to be only under a load when this happens. What could change when the engine is under a load? The reeds look good. I had the injectors flowed they are fine. ExhAust is ok. Harness and all of the grounds are ok. I'm making 38 psi at the rail at all times. It almost seems like a weak fire issue but I don't know how to check that.