98 XP LTD Sputters

[sea.doo.dan]

My craft recently stopped running correctly. It starts up fine. Idles fine, but will not go over 10mph. To me it sounds like its "misfiring." At idle speed, I hit the gas hard and the front will jump out of the water, then the craft will shut up. At a slow speed I can chop the gas but when given alot of throttle it sputters along and if i give it full throttle it will shut up.

Thank you very much for reading, hopefully your insight will help me recover my craft.

TGIF!!!!

 

[djredman99]

Does it run poorly at high RPMs on the trailer too or just in the water?

My first thought would be a fuel delivery issue. When, if ever, was the last time you cleaned/rebuilt the carbs? Also, do you have the old gray fuel lines? If so, regardless if it is your problem or not, you will need change the fuel lines.

You should probably do a compression test on your cylinders as well, just to know the integrity of your engine. If you do this, post your results. Also note the condition of your spark plugs.

Get back to us with that info and we'll see if those around here can give you an accurate diagnosis.

 

[Young-SC-Owner]

It really sounds like fuel delivery issues, Possibly the selector valve, the little filters in the carb, or going bad diaphragms...
Heck, or grey fuel lines.

 

[sea.doo.dan]

I have had it diagnosed. The compression is at F-120psi R-115psi. I have cleaned the fuel filter, checked electrical connections, checking the prop and pump & charged battery. checked carbs, fuel pump and fuel lines are ok. I did find that the oil pump drive was obscured by a vent hose causing the pump to hang wide open. The problem has not been fixed.

 

[djredman99]

checked carbs, fuel pump and fuel lines are ok.

Can you elaborate on this a bit. What did you actually do here?

If you have the gray fuel lines, they will need to be replaced, whether or not it is causing your current issue. They will deteriorate inside and clog your carbs/filters.

There are small filters inside the carbs that can become clogged. If you say your carb is ok, then I assumed you have cleaned the carbs, removed and cleaned the filters, inspected the diaphrams/o-rings/etc. and replaced any as necessary. Doing all of this would have required you to pull the carbs out of the machine.

I would search online for the Mikuni Carb manual, it is only ~30 pages long. Understand the carbs and the 'adjustments' for the different throttle ranges you have. You could be flooding your engine above idle...just lots of possibilities at this point.

 

[djredman99]

http://www.mikuni.com/pdf/sbn_manual.pdf

The Carb Manual