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Seadoo GTI Le RFI 787 with SBT Starter won't turn over with spark plugs in.

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  • Seadoo GTI Le RFI 787 with SBT Starter won't turn over with spark plugs in.

    This has been driving me nuts. I have a Seadoo GTI Le RFI 787 with a 9 tooth SBT Starter that is 4 months old.
    The starter will crank with the spark plugs out, but doesn’t with the spark plugs in.
    I can turn the engine over easily by hand at the PTO with the spark plugs out, and naturally it gets hard when it hits compression with the plugs in, but you can still push it over compression slowly by hand.
    There is no excess oil in the cylinders when it cranks with the spark plugs out.
    The starter pulls 59 amps at 11.2 volts with the spark plugs out, I have seen 300 amps with plugs in and the voltage drops to about 9.5 - 10 volts.
    If I time it right and get it spinning with a compression gauge in one cylinder, the compression is 150 psi in both cylinders.
    If I put 1 spark plug in and the compression gauge in the other cylinder, it gets to about 55 psi on the compression gauge and the starter stalls.
    I have bypassed all the solenoid and battery wiring by using heavy duty jumper cables directly to the starter motor.
    With the battery wiring and solenoid connected, the solenoid would just cycle by clicking in and out, without turning the starter.
    The armature has been machined and undercut and I checked the armature, there is no variation between segments at 0.010 ohms and no variation in readings horizontally apposed. I also checked the resistance in the same position as where the brushes run and there is no variation in the readings. There is open circuit between all the segments and the armature shaft.
    If anyone has any suggestions on how to fix this problem, I would be extremely grateful.

  • #2
    Where is Administration shopsbt.com?

    Where is administration? I'ts important. Thanks.

    Comment


    • #3
      Re: Where is Administration shopsbt.com?

      I finally worked out the best way to fix an SBT starter motor that won't turn over correctly is to replace it with a genuine Seadoo starter motor. I replaced what I believe would be the original starter at 333 hours. The first SBT starter only lasted 66 hours with a service to free the rusted brushes in between. It had been struggling to get over the first compression for the best part of a year. The second SBT starter lasted only 5 hours. Whatever I saved on the purchase price was blown apart by the time and money I spent trying to diagnose why a 5 hour old starter wouldn't turn the engine over. Because I couldn't source a genuine starter in time, I missed the best jetski experience in 50 years and probably won't get another chance in my lifetime. With the new OEM starter, the engine spins over really well, and because it is injected starts almost immediately. I am finished with SBT, it's only genuine Seadoo from now on.

      Comment


      • #4
        Re: Seadoo GTI Le RFI 787 with SBT Starter won't turn over with spark plugs in.

        I finally worked out the best way to fix an SBT starter motor that won't turn over correctly is to replace it with a genuine Seadoo starter motor. I replaced what I believe would be the original starter at 333 hours. The first SBT starter only lasted 66 hours with a service to free the rusted brushes in between. It had been struggling to get over the first compression for the best part of a year. The second SBT starter lasted only 5 hours. Whatever I saved on the purchase price was blown apart by the time and money I spent trying to diagnose why a 5 hour old starter wouldn't turn the engine over. Because I couldn't source a genuine starter in time, I missed the best jetski experience in 50 years and probably won't get another chance in my lifetime. With the new OEM starter, the engine spins over really well, and because it is injected starts almost immediately. I am finished with SBT, it's only genuine Seadoo from now on.

        Comment

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