1995 750zxi - runs great on trailer no power on water
 

HELP I'm drowning here. I've been working this problem for 2 years.

The ski will start on the trailer with one shot of the after market primer instantaneously. It will idle great and rev full throttle no problems (I know for less than 15 seconds so I don't burn it up). I attach the garden hose and still no problems runs great. THEN, place it into the lake. It will start, idle, and run but it will not rev up to full rpm until a wave comes and the prop comes out of the water then fully revs with no hesitation or breaking up. Once the prop goes in the water back to low rpm. It will go about 20mph according to the gauges. This machine used to go 55+ on the Hudson River. Here are the fixes I’ve done:

New pistons
New rings
New head gasket
New base gasket
new main jet in carb - 135 like kawi wants
Rebuilt carbs
New plugs
New gaskets in the exhaust
New bearings in the jet pump assembly


The ski has:
Vortex flame arresters
R&D ride plate
R&D intake grate
Solas 14-19 stainless prop

Diagnosis repairs I’ve done:
I also have a 900 zxi works fine. I took off the jet pump assembly and put it in the 750 in its entirety with the intake grate and still same problem.

While the 750 is running under load with the throttle at full I prime it to send gas into to carbs and nothing. It will bog sometimes or it will not be affected.

I check the clearance of the prop to the walls and it is .03mm. The service limit is .06mm.

I'm out of ideas.

My email is Greg_c3@yahoo.com

Thanks for reading.

i had an old seadoo that did this and it turned out to be a spark plug so i would try new plugs again (you do get bad ones) i would also replace the ht leads (plug leads), plug caps and after that i would start looking at things like cdi's and stators ect

p.s how free does the engine turn over when not under compression? (e.g bad main bearings)

I'll try new plugs and inspect the boots and wires. Thanks

With the plugs out of the engine I can turn the drive shaft by hand. With the plugs in I need a wrench to turn past the fire postions then I can turn by hand. There does not seem to be any rubbing or binding.

Fixing
 

Hi mate I have the same sick jet ski and want to know dit you get yours fixed and what did you do to get is fixed thanks

I just picked up a '95 750Xi and have the same issue.. ski runs great out of water, but once in, as soon as you accelerate it shuts off.. if you take your hand off the accelerator the engine goes back to idling.. I should add, when we pull it out of the water and run the bilge pump, a fair amount of water comes out..