Super Jet Please help guys! Rn issues been chasing a year now...

[Hollywood Hood]

So here it is I have a 97 Rn Superjet I went to the lake 76 times last summer fighting this issue and I can't take it anymore lol. I have completely replaced all of the electronics coil CDI plug wires spark plugs solenoid I have tried three different sets of carburetors and it does the same problem every set. I put the ski in the water fire it up has a ton of bottom end hit As soon as I get half throttle to full throttle it falls on its face I put it on the trailer with the hood off and the pump loaded in the water took the air cleaners off looked inside the carbs and as soon as I get half to full throttle the fuel instantly stops I have completely rebuilt the motor checked everything the only thing I have not replaced is the stator and the reeds everything else is Brand New. The fuel filters stay full and continually flow fuel It's like someone turns the gas off as soon as it gets half to full throttle What would make the pulse shutdown because that's what gives signal to the fuel pumps on the carburetor to suck fuel Why would a pulse lose signal? I have had some pretty good mechanics that know skis look at this Usually I can figure anything out but this one stumps me I lost sleep over this issue. Please help!! Thanks guys

 

[Byeai]

lol kinda hand same issue on my chicks 440 it would warm up and then u could idle but wouldnt go anywhere but if motors cold u could go full throttle half throttle water u wanted changed ebox and same thing and then stator stopped working changed it out and it fix it self

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[Dmac80sc]

Do you still have the fuel selector knob? If so try running the fuel line right to the carbs.

 

[Hollywood Hood]

No knob just primer

 

[Dmac80sc]

So your lines run right from your tank to your carbs? Have you check the one way valve?

 

[Hollywood Hood]

Yes lines run from tank through in line filters then right to carbs. One way valve on what? I'm not familiar with this? Thanks man

 

[chadetroit]

I think he is referring to the valve hooked to the air inlet on your tank, let's air in but not out keeping pressure so your fuel pumps out to your lines.

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[yldsix]

It could be temp sensor limiting rpms. Disconnect and see.

 

[Hollywood Hood]

Good idea but the have no temp sensor

 

[B3IS]

Did you install your one way valve backwards ??? (the little round white thing hanging off of the right side of the tank, is the little arrow pointing to the tank ???)

On sunday I did not see you run it with the hood off to take a look.

 

[sxipro02]

My one way vent was causing too much pressure in my tank and it would flood itself out after riding for a while. I took it out to bring the tank to zero pressure with just a vent line running up the handpole. Have had zero problem since. Your sounds a bit different though. Have you checked the simple stuff like pulse line for proper seal and possible crap stuck in the fittings or lines? possibly a crack in the fuel pick up line??? You got a weird one for sure. Good luck

 

[Nemo]

So you know for sure the carbs are working correctly because you swapped them out with known good ones. You're getting a good supply of fuel to the filter but not to the carbs. It sounds like you're sucking air after the filter somewhere. From there I would inspect the reeds and crankseals.

 

[Hollywood Hood]

I took the boat out Monday as well that's when I tested with hood off. I'm going to check reeds tank valve and crankcase seals today! Im going to hook up a scope and lap top to plug wires to see if I'm having voltage or spark dump at high rpms this week. Keep em coming guys I'm determined to find out what's wrong! This will not beat me!

 

[Byeai]

stator

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[Hollywood Hood]

Oh yeah it will also rev out full RPMs on the stand when the pump is not loaded the problem only happens under load when the pump is in the water if that helps

 

[jhall752]

if its not your reeds its your stator... mine is doing the same thing and it turns out my stator isgoing bad

 

[raytherace]

I ever had a problem like that on a SN of one customer. After 2 month of testing we finally found a crack on the cylinder.

 

[ArtMaybee]

Possibly lean on the top? have you tried opening the high screws more? I Had a ski two years ago that had a similar issue. Ran great on the trailer but would bog horribly around half throttle and up in the water. My friend kept telling me it was lean but I had a hard time convincing myself since I'd already opened the adjusters SO much following that assumption. After more fiddling with it, it actually did start running ok but the high-speed adjusters were out over three turns on stock 38s on a stock 62T 701. Knowing there was NO WAY I should have to open the adjusters that far on a stock motor with stock carbs I investigated futher. There was an air leak in the motor.

It would probably be a good idea to pressure test the motor. If it's an air leak, even if you can get big enough jets and/or adjuster settings to get enough fuel to compensate for the air leak, It will most likely never run right or consistantly. I learned the hard way that you should ALWAYS replace the crank seals when a motor is apart. The ones in my motor looked great, but were still leaky.

 

[MikeyB]

Leak-down test?

 

[ArtMaybee]

Also, I know a lot of people re-use intake and carb gaskets sometimes. Make sure those are in good shape as well since those leaking will cause lean issues too.

What seems strange is not seeing fuel at/past half throttle when looking into the carb throat. Having changed the carbs and fuel/pulse lines. There isn't much left to cause an issue of this sort. Unless an air leak is causing this as well. Air would attempt to follow the path of least resistance. If the pulse can travel in and out a leak easier than moving the diaphram to pump fuel..... That's probably what it will do.

Maybe also check for a fuel/pulse line that's collapsing. Maybe that could be an issue.