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93 Force 150 Engine Skip

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  • 93 Force 150 Engine Skip

    Ahoy, This is my first time to this forum and problems bring me here. I have a 93 Force 150 that I've owned since new. Motor has about 270 hours on it and has been trouble free except for a minor exhaust water leak which was repaired and at the time the dealer said the motor was in great shape. Today, after a long period of trolling followed by a wide open ride back to the camp, I took the wife for a ride later today and the engine started to skip. It got progressively worse and we returned home. I changed the plugs for new NGK's and drained the float bowls in the top two carbs. Blew air thru the main jets in those same carbs. Did not touch the bottom carb due to limited room to work and being over the water. Engine still skips. Appears to be blowing back thru the top carb when it skips. I don't have a manual and cannot trouble shoot without. Does this sound like a confused ignition module? Had a Harley act this way and new module solved the problem. Acts more like ignition that gas problem but really hard to tell at this point. Any chronic or typical Force 150 problems like this?Thanks,Rob

  • #2
    Re: 93 Force 150 Engine Skip

    Gotta narrow it down.First check for spark.If thats ok, examine the reed assembly between the intake and the block. If damaged or stuck open, can give the symptoms you describe.
    Medford, WI


    • #3
      Re: 93 Force 150 Engine Skip

      Roscoe,Appreciate the tips. Plan on talking to the Serv Mgr at the dealer as well. Was going to try an induction timing light on each plug wire to see if I could see a misfire. Never thought of the reeds. Two stroke experience limited to piston ported engines. Noticed that the ignition seems to have a separate coil for each cylinder. Little blocks that fit in a T-slot in a larger module. Are they replaceable?Thanks and regards,Rob


      • #4
        Re: 93 Force 150 Engine Skip

        The coils are definitely replaceable.If you come up with a suspected bad coil, swap it with another one to see if it is indeed a bad coil. If a bad coil, the problem will move to the new location. If no spark stays on the same plug even with a different coil, then it may not be getting a signal from the switchbox.Gas blowing back thru the carb is a concern.
        Medford, WI


        • #5
          Re: 93 Force 150 Engine Skip

          Roscoe,Blowback is not severe but definitely there. I really need to watch all three carbs to see if they all do it. If only one is doing it then I guess this may be an indication of damaged reeds on that carb, correct? I say this because I would expect all 3 carbs to see the same pressure peaks from the crankcase and all exhibit similar symptoms during a missfire or badly timed spark.Compression and spark test will be done this weekend. Have a gap type spark tester on order and it should be here on Thursday. Found a Clymer manual locally ($39.93 list price) and will get it if I cannot find an OEM manual. Do you happen to know what the firing voltage is for this motor, 20K, 30K, 40K volts?Thanks,Rob


          • #6
            Re: 93 Force 150 Engine Skip

            I once had a similar problem on my 89 150. The skipping got progressively worse. Ended up being a stator which is common for the Force 150 - that and starters.


            • #7
              Re: 93 Force 150 Engine Skip

              Thought I'd bring you all up to speed on what I found, which is really nothing. Bought a spark tester at NAPA and set it to 7/16" per the manual. Made an ignition grounding rig using a piece of #14 copper wire. With 4 coils grounded and one on the spark tester, I checked each coil separately and all 5 fired consistently. I did inspect all the wiring because another forum member with a 85HP skip found a pinched wire. I also found one of the trigger wires pinched behine the alum mounting plate that holds all the electronics. Inspect revealed no damaged insulation, but I slopped some liquid electrical tape on it just the same and added a few zip ties to the wires to hold them more securely. Fired up the motor and it ran like a watch. All I can guess is I got a shot of water in a the last batch of gas I bought. Tank holds 80 gal on my boat and I rarely have it full. Could have been condensation as well since it has been very hot and humid lately. A day fishing might have made for significant condensation in the tank. Thru a can of marine type dry gas in the tank and will keep my fingers crossed. I came up with a simply way to operate the key switch and be back by the motor and will post is separately under that subject.Thanks to everyone who made suggestions and offered assistance. If the problem returns, I'll be back whining again.Thanks and happy cruising.Rob