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  • f115 running bad

    I have an 03 f115 and it has always ran rough between 1300 and about 1500 rpms i changed plugs before going on water and seemed to do better at first but then started to run bad at all rpms except idle and would not turn over 3400 under a load. I checked the new plugs and they are white now like running lean and the old plugs that I originally changed were tanish brown which I think is normal. I've been reading things on here and tried them such as cleaning screen on high pressure pump and injectors and the throttle body while it was off. I'm thinking injectors still dirty. I ran the motor at idle and unpluged each injector one at a time and it did make a difference in the way it ran with each one pulled. I then reved up to about 1800 while it was running rough and did the same test and the #1 and #4 injectors when electric plug pulled made no difference in the way the motor was running. Could they b dirty still or an electrical issue somewhere? When pulled #@ and #3 the motor almost died. Also when I used my electric winches on the boat the rpms drop and I never noticed that before. Could that b just because it was already running rough while useing them?
    Last edited by empty shell; 05-27-2011, 11:50 AM.

  • #2
    F115

    Ok guys I recleaned the injectors and swaped them around and the #1 and #4 still make no difference when pulled while motor is running. Also switched coils around and the other one did the same thing in its place. Whats wrong? Could it b something else no sending it to the 1 and 4 cylinders coil correctly. Any help appreciated, losing time during the commercial shrimp season. Please help.

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    • #3
      why not take it to a trained yech and be done with it.
      faster than jacking about with something you know absolutly nothing about with no tools to work with.
      for the commercial guy a professional repair is always cheaper and eaisier and back on the water faster.
      you also need to check your charging system, low battery voltage at the ECU or main relay will affect engine performance as the ECU,fuel pump,4 injectors and two ign coils are all 12V powered.

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      • #4
        do it yourselfer

        I like to do things my self that y never brought it in yet, but I did all I can do and no luck so off to the shop. I did just put a new battery in the trip before last. Maybe not big enough?

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        • #5
          I work on a lot of commercial stuff.
          most my family and friends crab or net for a living.
          sometimes I even work nights to assist them.
          typically when they try something and just keep running it it makes a small issue worse.
          a bigger battery wont help if there is a charging system issue.

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          • #6
            new fuel system

            Ok just got word from the shop that injectors are dirty and the only way they will warranty the work is if the switch the motor over to the new style fuel system. My question is what is the difference in the system I have and new one? This is the first time I have this problem and the motor has a lil over 3000 hours on it. Y swap to new system when this one has done good?

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            • #7
              there is no new style fuel system.
              only thing yamaha added was a 10 micron filter between the fuel feed pump and the VST.

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              • #8
                Fuel

                Yeah I went to shop to find out what he was talking about and he finally said it was just a filter. On the phone he made it sound like there was alot more involved. Total for entire fuel system cleaning n fliter is $825. Still dont think it injectors but they are the experts.

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                • #9
                  I dont trust X spurts.
                  I do trust my test equipment.

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                  • #10
                    Originally posted by rodbolt17 View Post
                    I dont trust X spurts.
                    I do trust my test equipment.
                    Very true.
                    An X is a "Has Been" and a spurt is a "Drip" under pressure.

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