Mario Percopo
New Member
I just bought a 1996 Sea Doo Challenger jet boat with single rotax engine (787?).
The guy started it for me but we could not water test it since it needed a new throttle cable.
I did compression test it, both cylinders good at 150 psi.
I replaced the throttle cable and quickly found why it was broken. The carb linkage was frozen.
I tried WD40 and worked it loose but eventually removed both carbs, cleaned, sprayed, lubed them (did not open them for rebuild).
Boat starts and idles fine. Throttle lever moves freely and carb valves (flaps) open and close freely. Here is the problem, as I move the throttle lever it will only increase rpm a little before it starts reving up and down. I replaced leaking fuel lines with clear ones. I see air bubbles coming from the line on the front carb and traveling all the way back to the tank........
Any ideas?
I was told it was running fine before the cable broke. Then it sat for 8 months.
FYI..............
I solved the problem.
The fact that my boat was running off a hose in my driveway lead me to believe their is some type of governor/limiter set on the throttle where once you get past about 3000 rpm the engine begins so surge (race up and down) if you try to give it any more throttle. I put my boat in the lake. It started right up. I put it in gear to go slowly through the idle zone. Then I punched it and it took off like a rocket. It runs fine. I don't have a carb issue. The whole thing is based on a safely measure that won't let you rev your throttle above 3000 rpm if the engine is not in gear and not under load. Once I put the boat in the lake it was fine.
The guy started it for me but we could not water test it since it needed a new throttle cable.
I did compression test it, both cylinders good at 150 psi.
I replaced the throttle cable and quickly found why it was broken. The carb linkage was frozen.
I tried WD40 and worked it loose but eventually removed both carbs, cleaned, sprayed, lubed them (did not open them for rebuild).
Boat starts and idles fine. Throttle lever moves freely and carb valves (flaps) open and close freely. Here is the problem, as I move the throttle lever it will only increase rpm a little before it starts reving up and down. I replaced leaking fuel lines with clear ones. I see air bubbles coming from the line on the front carb and traveling all the way back to the tank........
Any ideas?
I was told it was running fine before the cable broke. Then it sat for 8 months.
FYI..............
I solved the problem.
The fact that my boat was running off a hose in my driveway lead me to believe their is some type of governor/limiter set on the throttle where once you get past about 3000 rpm the engine begins so surge (race up and down) if you try to give it any more throttle. I put my boat in the lake. It started right up. I put it in gear to go slowly through the idle zone. Then I punched it and it took off like a rocket. It runs fine. I don't have a carb issue. The whole thing is based on a safely measure that won't let you rev your throttle above 3000 rpm if the engine is not in gear and not under load. Once I put the boat in the lake it was fine.
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