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  1. #1

    1999 Seadoo GSX RFI Extremly hard start in water.

    My 1999 Seadoo GSX 787 RFI will not start or start very hard in the water. When I was preping this for summer after sitting all winter it started up pretty quickly in my garage. Ran it with water connected and made some checks on it for several minutes and stopped it. Next day started it in garage for few seconds then ran it down to landing 10 minutes later. After getting it in the water I tried starting it and it would not start. I held the throttle wide open while cranking and it finally started to sputter and started after 10 minutes but I still needed to feather the throttle to get it warmed up. Ran in for over and hour and shut it of a couple time during that time and it started up much easier but still not like I believe a RFi should. Brought it back and started doing some checks because an RFi should hit the start button and it should purr like a kitten. Checked fuel pressure and it is at 56psi, which is right on. It has a new battery, new plugs, new oil filter(yes I purged the air). Started just fine again in my shop today with a little effort and I tried to take it out again today but this time it would not start at all just minutes after it was running out of the water. Brought it back to my shop and it fired up with a little effort again. When I bought this last year the owner said that it was always hard to start and you had to play with the throttle to get it to run but it was never an issue like this. Im a auto and truck mechanic and I know this is not how Fuel Injection is supposed to work. Could someone please help me? As a mechanic I will be very disappointed if I need to go to the dealership for a fix.

  2. #2
    the only differance between land and water is engine load..

    Cranking speed - starter draw - 10.5 volt minimun

    Idle rpm - out and in water - 2800 and 1400 rpm

    Jet pump issue - check for debris

    These issue come to mind

  3. #3
    2000 GPRXP 4tec shooter98xpl's Avatar
    Join Date
    Dec 2005
    Charleston SC
    Man I don't know whats up with the RFI's this year, but my buddy has worked on 5 of these so far this year. Has the motor ever been rebuilt? I'd check compression and make sure thats right. If it is, I'd check the rotary valve timing. If thats correct, maybe check that the flywheel is on correctly. Or possibility is that your starter is finally about to take a big dump on you. Also something to check is that the gas spray looks good, might be time to clean that out. I don't know much about the rfi's, I think you got tps sensors on both the throttle bodies as well.
    I know my buddy chased this one problem for a while. He finally pulled the motor to find a small crack by the rotary valve that you couldn't see while in the hull. It was sucking air through this crack causing it to have hard starts as well and run rough on the water.

  4. #4

    Join Date
    Mar 2006
    I had problems w/ 1 of mine-- I reset the tps as per the manual and my starting issues were solved.

  5. #5

    Join Date
    May 2011
    Central Coast California.
    #1 thing to check is the compression. This is the most likely culprit to starting fine out of the water and bad in. Please clarify, is it hard to start in the water or cranks slow in the water?

  6. #6
    I forgot to mention I already checked the compression and it is at 145psi on both Cylinders. The jet pump is clean and clear. Its not that is cranks slow it starts hard. Cranking speed is the same in water as out. I think I may try the TPS reset. I checked the resistance on all major senors and they are all within specs as per the Seadoo service manual.

  7. #7
    Hello I am facing very similar issues, did you resolve your problem? If so what was the solution?

  8. #8
    Quote Originally Posted by oldbugger View Post
    Hello I am facing very similar issues, did you resolve your problem? If so what was the solution?
    No I have no solved the problem yet The ski has spent the summer inside and when I did make acouple attempts to run it I was stranded out on the river. Very disappointing. Sea doo will offer no help and tell you to take it to a dealer. I just lover that idea! Give them the ski so they can spend 1000 fixing it when its maybe worth 1500. Frustration!

  9. #9
    Check your rotary valve to cover clearance and also check your fuel pump pressure..

    Engines basicly need three things to run - fuel - spark - compression..

    A 2 stroke also needs a good fuel transfer.. If you have the above three things - then you need to investigate the other..

    If the rotary valve is not properly sealing off the incoming fuel charge in the bottom end - it will not transfer a full fuel charge to the top end, thus it will not fire ...

  10. #10
    I have proper pump pressure. I will see about the rotary valve clearance. Would that make a difference from being out of water to in water though?

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