RPM's erratic at high rpms. UGH

[CReynoldsMIZ]

So took the 96 gsx out yesterday night for an hour and a half to see if my new rave valves and starter solenoid cleared up all of my problems. Ski ran great for about an hour and fifteen minutes yesterday. Had a little light bog problem coming of idle after no wake zone but nothing that didnt clear up after a little blip of the throttle. Was running about 6700 rpms all day, which i know isnt max, but it has been ridiculously hot so i wasnt too worried. When i came out after a long period of idling around trees sticking up out of the water, i noticed that it seemed like i was hitting a rev limiter when i got to about 4500 rpms. When i would get to that part the rpms would start jumping erraticly as shown on my rpm gauge. I could get it going to about 5000 maybe a little more rpms but it was really jumpy on the rpm tach and nowhere near the power i had earlier. It almost felt like i had really bad cavitation but if that was the problem i should have felt it all day and then the rpms should still have hit my 6700 benchmark, right? Also, it ran perfect up to like that 4000-4500 problem area and idled perfect at about 1500 rpms in the water. When i took it out of the water, i could still feel it sort of cutting out, but it would rev up to the 6800 area. Any ideas? I ran on the trailer, and the water regulator is working fine, exhaust seemed cool, no leaks. Raves are new as well and set flush with the cap. It feels like something electrical, but idk. Maybe new plugs?

 

[CReynoldsMIZ]

okay guys, need some ideas. Pulled the pump today, wear ring is fine. Measured all around it and it is within spec of .04in. Filed down the edges of the impeller to clean up a few nicks. Put brand new spark plugs in for good measure. Cleaned the rave valves, one was leaking just a tiny bit, nothing major tho. Put the multimeter on the battery and reved the engine up a few times to check the charging system to make sure it wasnt overcharging, and i think it was fine ran pretty steady around 13.5 volts. Any other ideas? Im hoping that it was just bad plugs but ruling anything else out would be nice too. Also, carbon seal looks good and yesterday had no water leaking into the hull.

 

[bigJake]

I assume you have already changed the gray fuel lines and double checked that your raves are connected properly and working. if so, it could be your voltage regulator. measure the voltage on your battery again, this time looking for over 1 volt of AC voltage coming from the regulator, rev to about 5000 rpm.

 

[CReynoldsMIZ]

haha yes i have changed grey fuel lines, carbs clean, raves clean, perfect compression, water regulator works, no leaks, new plugs. Ill double check the voltage tomorrow, but when those go bad, dont they usually go crazy? Ive pretty much touched/replaced/repaired every part of this ski.

 

[bigJake]

the ac voltage will mess with mpem and cause erratic bahavior. easy enough to check so worth ruling it out

 

[CReynoldsMIZ]

So how exactly do I test it. The same way that I was with the multimeter?

 

[bigJake]

yes, just put it on AC instead of DC. If you put it in the water you can just disconnect the red wire from the regulator and take it for a test ride, it just wont be charging the battery.