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  1. #1

    Join Date
    Feb 2012
    Folsom, CA

    2001 951 Carbbed boat with severe rpm swings

    2001 RX Carbed. WCM Jet kit. This boat has been set up this way for 3 years and has run perfectly. I winterize and do all the PM.

    Current situation. Starts and idles fine in the water. Runs smoothly and pulls hard. It will run at 5k all day. If you Pin the throttle in snaps up to about 6500 and then immediatly falls back to 4850. After a second it feels like you pinned it again and it pulls hard for a second and then falls of again. If you ease it up to 7/8th you can get it to 6k again. Holding it WOT it will hold steady at 4850.
    The surging is hard on and hard off. No misses or back fires.

    Things I've tried so far.

    Fuel system:
    Pulled intake tube from tank. Filter is clear, all lines are updated. No grey sludge anywhere.
    Fuel filter is new, tried without and condition persists.

    Pulled and opened carbs. Internal filters are perfect. Looks like new inside. No corrosion.
    Checked return, pulse, and vents. All seems to be functioning correctly.

    Tested TPS. Functioning properly. Drops from 5 to .01VDC on Craftsmen meter set to 20VDC
    Clipped plug wires.
    Checked main ground to block and from mag cover to MPEM.
    Disconnected TPS. Jumped TPS.
    Disconnected Multi function gauge plug from MPEM.
    New plugs with correct Gap. (Rtype)
    Checked rear electrical box. Clean and dry.
    Switched MPEM.
    New Battery.
    No messages on Multi Gauge.

    Checked RAVE valves, ran with caps and spring off.
    Ran with Water regulator cap off. Hot Pipe. Seems to be working. It does seem a little loose on WB.
    Replaced coupler from pipe to water box. Hose from WB to exit is in Good condition. No blister or signs of delamination.
    Ran it on trailer in the water with seat off. No exhaust leaks.
    Last time I started it on the trailer after riding it didn't seem like much water came out of the exhaust.
    The only thing I can think of that I haven't done is pull the Water Box and check for an upstruction. Possible but unlikely.

    I've been working on SEA-DOOs for years and I've had some weird issues. I'v been working on this one for a month and reading every 951 thread I could find.
    So far the TPS seemed the most likely culprit.
    I'm at a complete loss. Any help is really appreciated.

  2. #2
    SURFnTURF's Avatar
    Join Date
    May 2007
    You have done everything what I would have tried.
    I feel its electrical if its surging hard on and hard off.
    Seems like its the TPS playing up or you have a crappy coil gone bad.
    Both these display the same symptoms cutting in and out and not keeping revs.
    Have you checked the grounds on the coils as these are a shitty set up and can come loose in the black box.

  3. #3
    the TPS changes the timing curve at about 80% throttle..
    My only other thought would be leaking fuel pump check valves..

  4. #4
    SURFnTURF's Avatar
    Join Date
    May 2007
    If the TPS is defective it doesn't matter if it runs under or over 80% throttle ,revs will be erratic and it just wont run properly.

  5. #5

    Join Date
    Apr 2010
    South East
    Does that one have a soleniod that operates the rave valves? If so, you might have a bad connection or bad solenoid or signal going to, or maybe an air leak.

  6. #6
    rave increases the upper rpm only - at 4880 rpm the rave are closed..

  7. #7
    Have you tested for any power coming out of the stator/mag housing? I had a similar problem 2 years ago and never figured it out until this year (didn't have much riding time last year at all, maybe 3 trips out) so I didn't fix it.

    Turns out my pickup mounting bracket was broken not reading the mag to spar correctly. If that pickup has ANY metal shavings on it, the correct spark reading won't be produced.

    My ski died and I thought it was a plug, limped to shore only revving 4k, got home changed plugs ran mint. Went to lake following weekend, no start at all. Sat this way until a month ago when I fixed it.

    If you want to try somethings mentioned in my thread.

    Hope it helps
    Last edited by jwick86; 07-07-2012 at 04:27 PM. Reason: added link

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