94 SPI engine studders at full throttle

[lastnerve]

OK, I hope someone can help me out here,

This problem occurs only at top end. Everything runs ok at idle and midrange. Will only run aprox. 25 mph as opposed to 40 that it use to run. I've dis-assembled the carb, cleaned it, and put it back on. That did nothing. I then took a carb off my other ski (96 spi same engine) and still did not solve issue. I've also changed plugs.

I was told that if the temp sensor was reading wrong that it would retard the timing? so I took the sensor wire off and still have the problem. Could this be something with a rev limiter or timing issue. maybe plug wires.

This problem started after bringing it out of storage this year. Last year it ran great up to the time of putting it away for the season.

Any help would be greatly appreaciated.
Thanks,
-John

 

[rexsteiner]

If your only doing 25 tops it sounds like your cavitating and hitting the rev limiter. Check your impellar wear ring clearance.

 

[lastnerve]

I had the impeller unit torn apart last year to replace the driveshaft carrier bearing at that time the wear ring clearance was within tollerance. Everything looked good. Only has around 8 hrs. on it since then. Is there anyway I can unhook the rev limiter? or check it?

 

[Chester]

I agree with rexsteiner. Check your wear ring and impeller for damage. It's cavitating. 8 hours on a new wear ring means nothing when it can be trashed in seconds when debris goes through the pump.

Chester

 

[lastnerve]

Just checked the wear ring, It's good.

 

[lastnerve]

Update: Found the problem to be plug wires. Runs great now. Thanks for your help guys.