Fuel tank pressure 97 GTX

[CRei]

What’s going on guys picked up these two check valves, have not taken these out yet. Are they both tied into the same vent line on ski? Removing the old ones show which direction these belong in? Thanks

 

[Ckrawiec]

I've never seen a grey one like that...the other one is the typical one I've seen....as far as direction......blow into it, it'll only work one way. I think the white side is air IN, but double check.

 

[JJinSC]

I believe the gray one is the pressure relief. It would be the one under the rub rail. It is pretty hard to blow hard enough to make that one pop loose with your mouth. but the arrow should show which direction. The other should let air in. You should be able to test that one by blowing in direction of the arrow. It should not let you blow the other direction. That vent goes in the thru-hull that is up higher than the tank

 

[CRei]

Ok great ! I hope this is my problem ski runs good on land, will take off in water for about 50 yards then have to pump throttle, changed selector OEM water separator filter complete new OEM set of carbs rebuilt twice with OEM Kits tried another pair of carbs and same thing, thinking now fuel pressure not holding?

 

[CRei]

So I’m guessing you want to hold pressure in the tank?

 

[mikidymac]

The tank doesn’t need to hold and pressure for your ski to run correctly. You just don’t want a vacuum on it.

 

[CRei]

Sooo with that should the check valve hold pressure on the line or breath out to the outside, my ski is missing the valve ? Thanks man

 

[mikidymac]

The upper valve should let air into the tank not out. The lower valve with the pressure relief should let air out not in.

 

[Seadoo timebomb]

Why do so many posts refer to the tank needing pressure? The tank is not pressurized. But if you shake a sealed container full of gas it will build up some pressure. The slightly positive pressure in tank just prevents any chance of water getting sucked in. Has nothing to do with fuel management.

 

[Seadoo timebomb]

The grey one is a 1.5 psi pressure valve. The other one is just a check valve.

 

[CRei]

I’d like too also bypass the selector, what is the correct way to do this? In of selector direct to in of carbs? Do I plug other two lines

 

[JJinSC]

Take reserve line off of fuel selector and run straight to filter. Take the “on” line from the fuel selector and plug.

 

[CRei]

Ok just leave “in”from tank on valve?

 

[JJinSC]

No. The only thing left on the valve will be the “out” from valve to filter. Only the filter end will be left hanging because you now have the reserve line connected there. The “in” line to valve should be pulled from the valve and plugged.

 

[CRei]

My apologies just had one of those brain farts duh. Thanks again one of those days

 

[CRei]

Well back to the drawing board, installed check valve and bypassed fuel selector res and out connected directly with lamps on line, lines seemed to have pressure fuel was spraying out. Ok so off to the water, fires right up idles good, take off get about 10-15 yards falls flat on its face won’t go above 3500. Another thing noticed was the info gauge rpm said 8000, hours were 3 lines - - -. Compass flashing and hi temp. That really does not bother just want it to run well, think a rectifier? Or should I put this thing out to pasture, really would like to get to the bottom of this thanks guys

 

[JJinSC]

Well, I have heard of the rectifier causing the MPEM to function crazy. I’ve never had the issue myself. Hopefully one of the others that know that issue can chime in here and tell you how to eliminate that. I think it is pretty simple, like pulling the red wire loose.

 

[noviceskier]

I know it sounds really simple and may've been done already. But what plugs are you using? How do they look? Are they new? Falls on its face like it wants to die? Does it die? Or does it feel like it hitting some sort of limiter? Battery all good?

 

[CRei]

 

[CRei]

Hey thanks for the response, does not die full throttle needle stays at 3500. Return to idle then take off again then back to same thing. Very rarely stalls but fires right back up. At the 3500 rpm I pull choke and stalls immediately. Batter is new full charge on it 13.5 13.8 at idle. Have to check rev up, pulled caps on raves they move up down freely. Is there a rev limiter in the MEPM? Ordered a new OEM rectifier.

 

[Ckrawiec]

>> Is there a rev limiter in the MEPM? << Yes, 7200 rpm +/- 50.

I don't think I've seen any mention of any CARB service......are the carbs in good shape. ALMOST ALWAYS....if the ski starts falling on its face in the water....bad fuel delivery to the engine through the carbs.....cleaning MAY help but might be time for re-builds....genuine Mikuni parts ONLY though!

 

[noviceskier]

If those are the plugs you're running on the ski I'd suggest swapping them out, I know it's a different ski but I had the same exact issue on one my kawasaki 750s, wouldn't go past 3500rpm, anything below that it was fine. Fouled plug.

Cheap thing to check since they're only a couple bucks, think the service manual gap should be at .21?

 

[JJinSC]

I agree with novice, those plugs look old and rough. These are resister plugs, I have found they do not last more than about a season before causing symptoms. At least with as many hours as I put on them.

 

[CRei]

Ok great I’ll get to the bottom of this sooner or later, I’ll pick up some plugs? What’s your guys thought on a rectifier? Or and faulty MPEM??

 

[POPPS]

Ok great ! I hope this is my problem ski runs good on land, will take off in water for about 50 yards then have to pump throttle, changed selector OEM water separator filter complete new OEM set of carbs rebuilt twice with OEM Kits tried another pair of carbs and same thing, thinking now fuel pressure not holding?

I doubt it's any of your check valves,,the pressure in your gas tank has nothing to to do with the fuel pressure in your carbs,,,,sure sounds like carb/fuel delivery issue,,,sounds like they are lean out of the hole,,,try running the fuel from the pickup directly into the carb,,,