Super Jet Another not reving past half throttle thread with Video , I need help

[5bulldogs]

Here are a couple of videos of my SJ. It will rev fine on the trailer (1st video) but as soon as it goes in the water it will not rev past half throttle(2cd and 3rd video). At the beginning of the 3rd video it revs up higher after hitting the primer but dies down soon after.

I have replaced:
fuel
fuel line
pulse line
carbs
reeds
coil
ignition box
plug wires
plugs
disconnected the heat sensor

Any help on what to try next,

 

[Matt_E]

Did it just start doing it? Did it run fine at any point that you've owned it?
What carb(s) was/were on it and what did you replace it with?
What is the jetting?
Other motor specs?

 

[1hydroman]

had the same problem get rid of the primer that was my headache for two months

 

[5bulldogs]

Did it just start doing it? Did it run fine at any point that you've owned it?
What carb(s) was/were on it and what did you replace it with?
What is the jetting?
Other motor specs?

It has done it since the day I bought it. None of the changes have made ANY difference to the way it is running.
It had a set of taper bored 38's I replaced them with a set of stock 38's
jetting is 75 and 135
Stock 701 - 155 psi per hole

 

[5bulldogs]

had the same problem get rid of the primer that was my headache for two months

I bypassed the entire fuel system and let it draw straight from the fuel can, no change.

 

[5bulldogs]

A couple of more things to mention:

1. The exhaust gets very hot at the expansion chamber area. Just with that little bit of running in 65 degree water it is so hot you cannot put your hand on it. I have replaced all the cooling lines and cleaned out the top riva water hole. I also restricted the pisser with no luck.

2. In the water if you stay on your knees and go in a circle and let the exhaust get out of the water it will very slowly build the rpms up to the point of full throttle. Then as soon as you turn the bars straight and it cavitates the pump over your wake it dies instantly.

 

[Waternut]

It really sounds like there is a massive restriction in the exhaust. Since it runs fine on the trailer when dry and the pipe gets really hot in the water, I'm betting the pipe is cracked or broken and water that should be cooling the pipe is actually pouring into the chamber/engine and causing it run so poorly. Normally it clears up with a faster engine but in this case, the faster the engine, the more water you dump into the system. Any chance that smoke comes out of the pisser when you run it dry?

 

[Penken]

couldnt it be timig?
just a guess. i´m thinking about hot pipe buttons for sleds. they do something with timing to heat the pipe up. when it does so it wont rev up.
this is just a thought someone with greater knowlege can shime in.

 

[john_650sx]

couldnt it be timig?
just a guess. i´m thinking about hot pipe buttons for sleds. they do something with timing to heat the pipe up. when it does so it wont rev up.
this is just a thought someone with greater knowlege can shime in.

agreed, check the timing.

i don't like primers - they are just a work around for a poorly set up carb IMO.

 

[Zeon]

dont bypass the primer. Take that crap right out. Seriously. Make sure that tank is pressurizing. REMOVER PRIMER COMPLEATLY. Try again, Let her run , then open the tank and see if its pressurized. If still not with the primer out, Replace the one way valve. Ive had my one way valve come and go and it messed with my head for a long time.

 

[5bulldogs]

dont bypass the primer. Take that crap right out. Seriously. Make sure that tank is pressurizing. REMOVER PRIMER COMPLEATLY. Try again, Let her run , then open the tank and see if its pressurized. If still not with the primer out, Replace the one way valve. Ive had my one way valve come and go and it messed with my head for a long time.

I tried to run it with the fuel cap off with no change. I will run a new fuel line for the "on" circuit and try again.

So it should pressurize while running?

 

[5bulldogs]

It really sounds like there is a massive restriction in the exhaust. Since it runs fine on the trailer when dry and the pipe gets really hot in the water, I'm betting the pipe is cracked or broken and water that should be cooling the pipe is actually pouring into the chamber/engine and causing it run so poorly. Normally it clears up with a faster engine but in this case, the faster the engine, the more water you dump into the system. Any chance that smoke comes out of the pisser when you run it dry?

I thought all boats have some exhaust coming out of the pisser~?

What if I pinch off the water coming in for the first 15 seconds once the water. If the pipe is cracked and letting water in, it should run better.

 

[Zeon]

If there was no change with fuel cap off My opinion is your tank is not pressurizing. Your tank builds up pressure to push the fuel into the carbs. As much as the carbs suck fuel, With no pressure it wont run that great. The carbs are sucking just enough fuel to keep her running, but with no tank pressure ur starving that motor.

Remove your one way valve from ur tank, see if you can blow through it both ways.... if so its junk. The one way will let the air into the tank but not let it escape.


Listen, on troubleshooting, make it easy. No on off switches for fuel, Hook a return line up right to the carbs to the tank, and a line direct from the tank to the carbs for fuel delivery. then make sure ur one way is working and let her run. After a little bit of run time the tank will pressureize and when you remove the cap it was ***PPSSSSSTTTTTTT***** like ur opening a bottle of beer.

If your tank does not pressurize it will not run good. Gaurenteed.

 

[Waternut]

I thought all boats have some exhaust coming out of the pisser~?

What if I pinch off the water coming in for the first 15 seconds once the water. If the pipe is cracked and letting water in, it should run better.

The only time I've seen smoke coming out of the pisser is when the head gasket is blown or there's some other problem. The water jackets, especially in a dry pipe configuration, don't enter the exhaust flow until right before the waterbox.

Pinching the line should make a little difference but you'll have to kink it or squeeze it with pliers to really make a difference in flow.

I've accidentally run my ski's without the cap a few times and it runs wierd but it still runs well enough to plane off and jump waves before wondering what happened to my power. Yours sounds like it can't even maintain an idle.

 

[sjetrider]

May be a repeat here but dont want to read the entire thread. Sounds like a stator issue to me.

 

[5bulldogs]

May be a repeat here but dont want to read the entire thread. Sounds like a stator issue to me.

I performed the ohm test on the stator and it passed.

Could it be the stator if when you prime more fuel in the motor it runs better?

 

[Zeon]

I performed the ohm test on the stator and it passed.

Could it be the stator if when you prime more fuel in the motor it runs better?

NO. Listen, TRY what I said. I CANT STRESS IT ENOUGH. No offense to alot of the guys on here but alot of you have a ton of money to blow on a ski. Just try what i said before you start wasting your money on pricey parts... a one way check valve will ruin your riding. I use what I have and Ive had some poor boy set ups. I have been through it all when it comes to problems. TRY what i said, then come back on here and post some updates. Check that one way on the tank and simplify that fuel system

 

[Zeon]

I listened to it again.. That ski is STARVING for fuel

 

[SUPERTUNE]

From what I see and hear, way too lean, so lean that it just dies right out without any load.
Look for any crankcase leaks.
Definitely a fuel starvation, so something is wrong with the fuel system, carb rebuild and settings, bad case, seal, or air leak and/or is just flat out jetted wrong.
Start by making sure your low speed screws are set at 2 1/2 turns out then see what you have.

 

[swapmeet]

This thread is helpful to me.