96 XP 15mph/run away

[Logan.mchose]

Hello, I cannot figure out what’s wrong with my ski, it only runs 15mph in water and now when I start it on the trailer it seems like it’s running away.. I rebuild the top end of the engine. Put a new rotors valve in. Rebuild the carbs with the mikuni carb rebuild kit and set the pop off to 35psi. Redid all fuel lines. New plugs. Had the computer paired to a new key. I’ve had it running on the trailer in the water and set the idle set screw so it stays running. Every time while testing it the buzzer keeps a steady beep so I replaced the temp sensor, stopped buzzing. Tried to start it today and it is back to buzzing constantly and also seems like it is running away. So I backed the idle set screw out almost all the way so it doesn’t idle up and it still seems like it’s running away so I pull the key when that’s happening. I have no idea what it is and am just at a lost of what to do… maybe it’s the rotary valve because it doesn’t have the right tolerances? Or it’s the fuel sending unit not giving it more than 35 psi? These are my only two thoughts. I haven’t tried it on the water with the new temp sensor yet, Ik that it thought it was overheating with the buzzing and temp light being on during my previous water tests. So I was thinking it was in limp mode and not getting enough fuel to switch to the high speed jets?? I have 93 octane in it and jets are set at 0 for the high speed and 1.5 for the low speed. I might just try to find a jetksi mechanic to bring it to because I’m losing my mind with it by now..

 

[burtshaver2021]

Try pulling the choke when it’s running away. Did you test after rebuilding the carb to make sure the needle or seat wasn’t leaking?

 

[Logan.mchose]

Try pulling the choke when it’s running away. Did you test after rebuilding the carb to make sure the needle or seat wasn’t leaking?

Yes I had to pull it one time when the button or pulling the key didn’t work, pretty scary. Yes I did when I was doing my pop off tests on them I left them each for like an hour and they held, different psi’s but still held

 

[mikidymac]

Sounds like you have an air leak. Did you pressure test the engine after the rebuild?

 

[Logan.mchose]

Sounds like you have an air leak. Did you pressure test the engine after the rebuild?

No I have not, how do I do that?

 

[burtshaver2021]

To do a leak down test you will need to block the intake between the carbs and intake manifold, block between the tuned pipe and exhaust manifold, also take the rave vallves out and block there, pressurize the crankcase with 8 pounds through the pulse fitting and see if it holds pressure for 8 minutes. If it doesn’t hold, find your leak. If it does leak, try pressurizing the rotary valve cavity in case it’s leaking in there. Could also be a leaking carb gasket or fuel system could be sucking air, what type of fuel line do you have? Did you change the fuel filter square o ring? Change the fuel selector valve? Or pressure test the fuel system?

 

[Logan.mchose]

To do a leak down test you will need to block the intake between the carbs and intake manifold, block between the tuned pipe and exhaust manifold, also take the rave vallves out and block there, pressurize the crankcase with 8 pounds through the pulse fitting and see if it holds pressure for 8 minutes. If it doesn’t hold, find your leak. If it does leak, try pressurizing the rotary valve cavity in case it’s leaking in there. Could also be a leaking carb gasket or fuel system could be sucking air, what type of fuel line do you have? Did you change the fuel filter square o ring? Change the fuel selector valve? Or pressure test the fuel system?

Ok gotcha will do that tomorrow! Do I need to plug the oil in and return when I’m pressure testing the block? I think it’s like 1/4in fuel lines, I replaced the fuel selector valve. No I didn’t pressure test the fuel system. My fuel filter o ring is a circle. If you don’t mind could you explain the fuel system pressure test as well?

 

[burtshaver2021]

Ok gotcha will do that tomorrow! Do I need to plug the oil in and return when I’m pressure testing the block? I think it’s like 1/4in fuel lines, I replaced the fuel selector valve. No I didn’t pressure test the fuel system. My fuel filter o ring is a circle. If you don’t mind could you explain the fuel system pressure test as well?

You don’t need to plug any of the oil lines when doing the leak down test on the crankcase. If you are pressure testing the rv cavity you would apply the pressure on the rotary valve supply fitting and block the return fitting. The fuel filter o ring is round but if you look closely it’s in the shape of a rectangle. When pressure testing the fuel system I just take the fuel supply line off at the carb and apply 2 or 3 pounds of pressure, vacuum would actually be better as that side of the fuel system is under vacuum but I messed up my first Mitty Vac using vacuum so... then take the line off at the top of the tank, plug the line you are testing and turn the selector valve to the same ( if you’ve plugged the end of the ON fitting at the top of the tank turn t selector to on. I actually just pressure tested the selector valve and fuel filter because I really trust the black continental fuel line I used.

 

[mikidymac]

You can leave the RAVE valve in, if they are good they will hold the 8psi no problem. I only block the intake and exhaust when pressure testing.

 

[Logan.mchose]

You don’t need to plug any of the oil lines when doing the leak down test on the crankcase. If you are pressure testing the rv cavity you would apply the pressure on the rotary valve supply fitting and block the return fitting. The fuel filter o ring is round but if you look closely it’s in the shape of a rectangle. When pressure testing the fuel system I just take the fuel supply line off at the carb and apply 2 or 3 pounds of pressure, vacuum would actually be better as that side of the fuel system is under vacuum but I messed up my first Mitty Vac using vacuum so... then take the line off at the top of the tank, plug the line you are testing and turn the selector valve to the same ( if you’ve plugged the end of the ON fitting at the top of the tank turn t selector to on. I actually just pressure tested the selector valve and fuel filter because I really trust the black continental fuel line I used.

Ok gotcha will do. I’ll check the fuel filter o ring too. Alright so basically just test the filter and selector got it!

 

[Logan.mchose]

You can leave the RAVE valve in, if they are good they will hold the 8psi no problem. I only block the intake and exhaust when pressure testing.

Ok I kinda thought so since they’re a closed system. Got it I’ll do the same!

 

[Logan.mchose]

You don’t need to plug any of the oil lines when doing the leak down test on the crankcase. If you are pressure testing the rv cavity you would apply the pressure on the rotary valve supply fitting and block the return fitting. The fuel filter o ring is round but if you look closely it’s in the shape of a rectangle. When pressure testing the fuel system I just take the fuel supply line off at the carb and apply 2 or 3 pounds of pressure, vacuum would actually be better as that side of the fuel system is under vacuum but I messed up my first Mitty Vac using vacuum so... then take the line off at the top of the tank, plug the line you are testing and turn the selector valve to the same ( if you’ve plugged the end of the ON fitting at the top of the tank turn t selector to on. I actually just pressure tested the selector valve and fuel filter because I really trust the black continental fuel line I used.

Ok so I blocked off the exhaust and carbs like you said and it didn’t hold any pressure so I took a cigarette and blew smoke into the pulse fitting. Some came out of the cylinders so I pulled the “head cover” and 4 bolts were pretty loose so I cranked them down. Put it all back together and still didn’t hold any pressure with the mikuni pop off tester I got, so I put some compressed air in slowly and watched the oil go up the in line and pop the pressure release valve on the oil reservoir so I think I’m good on the block now! Just gotta test the fuel system tomorrow and see if the filter or selector valve are good. I’m just really hoping it can go over 15mph now lol

 

[burtshaver2021]

Ok so I blocked off the exhaust and carbs like you said and it didn’t hold any pressure so I took a cigarette and blew smoke into the pulse fitting. Some came out of the cylinders so I pulled the “head cover” and 4 bolts were pretty loose so I cranked them down. Put it all back together and still didn’t hold any pressure with the mikuni pop off tester I got, so I put some compressed air in slowly and watched the oil go up the in line and pop the pressure release valve on the oil reservoir so I think I’m good on the block now! Just gotta test the fuel system tomorrow and see if the filter or selector valve are good. I’m just really hoping it can go over 15mph now lol

I’m a little confused, if it’s not holding the 8 pounds of pressure then there’s an issue and you should find the leak. @mikidymac will know what’s going on

 

[mikidymac]

There is no "pressure relief valve" on the oil system.
If you put air into the pulse fitting and get air out of the oil lines then your inner crank seals or rotary valve seal is shot.
You have to make sure the engine holds pressure before doing anything else.

 

[Logan.mchose]

There is no "pressure relief valve" on the oil system.
If you put air into the pulse fitting and get air out of the oil lines then your inner crank seals or rotary valve seal is shot.
You have to make sure the engine holds pressure before doing anything else.

Ok gotcha will do!!