Super Jet Power drop off at high revs

[Birsey]

Hello Everyone. New member needing immediate assistance. Sorry for being needy! My son has a standard engined 2003 Superjet which starts and runs great up to 3/4 throttle and then it just won't rev any higher. The issue is the same in or out of the water. I can't decide if it is electrical or fuel. We have owned it for a couple of years but I've not ridden it before so not sure if it has been like this since we bought it. but as my 2007 model has developed its own issues we are currently sharing one ski. Any ideas where to start looking?? Cheers Chris

 

[bored&stroked]

Exhaust leak into engine bay would be the first thing I check since you can do it on the stand.

 

[Vortex]

That ski is about old enough for stuff to just start going bad. Coil/plug wires, reed petals, cdi if it was cranked over a lot with the plugs not grounded, etc. what do the plugs look like? Has the fuel system been maintained? Wouldn't hurt to do a proper compression test

Weird electrical issues tend to sound sort of ok out of water then run really bad under load. Fuel is more of hiccups and stumbles/hesitations

 

[BIRDMAN]

95% you need a stator

One of the coils are bad get a used one or send it to jss for repair good luck

 

[Fro Diesel]

That ski is about old enough for stuff to just start going bad. Coil/plug wires, reed petals, cdi if it was cranked over a lot with the plugs not grounded, etc. what do the plugs look like? Has the fuel system been maintained? Wouldn't hurt to do a proper compression test

Weird electrical issues tend to sound sort of ok out of water then run really bad under load. Fuel is more of hiccups and stumbles/hesitations

Hm...i guess i should get a NEW superjet then, bc my old one is just old and well not good anymore. Seriously, you can't check the health of a ski by looking at plugs, unless you swim the ski to shore.

Replace fuel filter, clean internal carb filter, check compression, verify strong spark. Also, I second the exhaust leak symptoms

Is there ethanol in the gas in the UK?

 

[smoofers]

I think OP needs to give a bit more info. Is the ski bone stock? When was the last time any service was done (rebuilt carbs, winterize, etc.)? Was the work done by you or a mechanic? Has the ski EVER had the carbs or fuel system cleaned/rebuilt?

 

[Birsey]

Hi All. Sorry for the slow reply. The ski is 1500 miles from my home!! I have rebuilt the carbs with genuine mikuni kits. Changed spark plugs, cleaned all the fuel lines and changed fuel but the problem is the same with or without the hood on. The motor is stock apart from some aftermarket air filters. I intend on taking a second hand stator and CDI unit with me on my next visit which will be in February. Any other ideas welcome. Cheers

 

[Birsey]

Hi All. Sorry for the slow reply. The ski is 1500 miles from my home!! I have rebuilt the carbs with genuine mikuni kits. Changed spark plugs, cleaned all the fuel lines and changed fuel but the problem is the same with or without the hood on. The motor is stock apart from some aftermarket air filters. I intend on taking a second hand stator and CDI unit with me on my next visit which will be in February. Any other ideas welcome. Cheers

 

[Birsey]

Just noticed, I have never mentioned that the issue feels just like the engine has an ignition Rev limiter that is set too low. Cheers

 

[Quinc]

Hook up a cheap tachometer and see what the rpms are. I think a stock SJ is around 6400-6500rpms, and the rpm limit should be around 7100.

 

[trotty]

Is the one way valve on fuel tank working properly as this pressurises the fuel so at high rpm it doesn't starve the carb. This was my problem when I was at wot and it just died on me.