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Running issue on an Older Trophy-gctid358286

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    Running issue on an Older Trophy-gctid358286

    A friend of mine has an older trophy with a single V-6. It was running rough and I found a bad wire, so I replaced the cap, rotor, plugs and wires. I checked the timing and adjusted the carb (Holley 4-bbl).

    We took it out for a test run and I noticed a vibration. He would run the throttle up and it just wouldn't get on step. In fact it backfired through the carb. He tells me it has a cobra outdrive. The engine runs great! It appears something in the outdrave is messed up preventing the boat from getting up on step, loading the engine which causes it to backfire.


    A backfire in a carbureted engine generally indicates a timing issue or an air to fuel mixture issue. I don't know what outdrive issues could cause a backfire in the engine. I've never had the problem so maybe someone who has will chime in here.


      While water in the fuel would not cause a vibration (unless the engine is not running on all six), it could cause a backfire. Check all filters, and replace the fuel/water separator if it has one (If not, install one). Does the propeller have any obvious damage? Once again, shouldn't cause a backfire, unless it is really damaged. Check the oil in the leg. If it's milky, it will indicate a leak somewhere, and possible interior damage. I'm betting that the problem is somewhere in the engine compartment.
      Bob Hawes.
      Kelowna, B.C.
      1998 Trophy 2052 WA
      4.3 Vortec, A1 G2


        Thanks all. We replaced all the fuel filters. I suggested to him to pull the boat and have someone look at the outdrive for the vibration, then go from there. Will keep you posted.


          If this is a Cobra drive it will be using an ESA. If one of the micro switches is out of adjustment, it can and will affect the ignition.

          If the ignition is being interrupted, it may explain both the low power and the vibration.

          Rick E. (aka RicardoMarine) Gresham, Oregon
          2850 Bounty Sedan Flybridge model
          Twin 280 HP 5.7's w/ Closed Cooling
          Volvo Penta DuoProp Drives
          Kohler 4 CZ Gen Set

          Please, no PMs. Ask your questions on forum.