Speedster SK RPM fluxuates

[rbhevo]

Greetings,
I'm new to the Sea Doo world, but have boated for many years. I bought a 1999 Speedster SK (717 motors) last fall and honestly it has never run 100% - one problem after another -------
Hopefully you folks can help - I can't keep throwing money to the local mech. I can replace anything, but troubleshooting in another story.
Here's the current issue
1) Above 4500 RPM the RPM on the left motor surges to approx 6000 then back to about 4500. If I position the throttle correctly it will do this all day. If I push the throttle to far forward, the motor will shut down.
3) Motor will shut off when trying to launch. Only way to get on plane is to ease left throttle up and match power with right motor.
4) At about 4400 RPM the motor will run fine.

Carb has been rebuilt
Fuel filter has been replaced
Plugs have been replaced
Swapped fuel pumps between motors

Any idea's??????? I'm at a loss! !!!!
Thx,
Russ

 

[Coastiejoe]

Unplug the rectifier. If the problem goes away, replace it. When these start to fail they can produce A/C voltage. If they do, it screws with the engine big time. So by unplugging, you will know if that is your issue. The battery will NOT charge while this is unplugged. And, I would find a way to put a little pressure on the fuel lines. See if you can produce a leak. If it leaks, it will suck air....


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[Waterluvr]

The problem is pretty apparent when you are pushing the accelerator all the way forward and the engine shut's off with surging at around 3/4 throttle, your needle/seat and diaphragm aren't working properly and some testing needs to be done on that carb to find out why component failure isn't the only usual suspect that comes into play with those. Verify proper operation in and out on the fuel pump and check the pump diaphragm first before getting into the carb, I vacuum test the impulse line on those also.

You need to check the bushing seals on the throttle shafts for vacuum leaks, leak/pressure test the carb fully assembled and leak test the seat and pop off test the needle from the filter housing inlet only and inspect the mylar film on the check valve assembly for damage and correct position and operation.

On Edit:
That surging is not doing your engine's longevity any favors but for future reference when a motor starts acting up like that just pull and hold the choke open and take note of how the engine responds to that, it will tell you pretty much everything you need to know in order to get an idea of where to look.

 

[96spxpos]

[MENTION=74818]rbhevo[/MENTION] I would do exactly that to diagnose your issue and take note of it.. That's exactly how I diagnosed mine... Eliminates electrical and rectumfier (lol) issues stator issues, spark plug wire issues, etc.. Isolating it to a fuel delivery issue will save you tons of time and money that you obviously don't have, or we all wouldn't be on this forum..
I would take it out and play with your choke a bit and see what happens. Report back the results.. Good luck