**Fuel Pressure Problem**

[FLYBYU]

If your sitting on the sled looking forward the line on the left side (pto side) is the fuel in line, the other side (mag side) is return.

 

[jaydaniels]

Okay, now we are getting somewhere. There is no reason for there to be any pressure in this line then correct? If there is and its blowing the line off then I would think there must be a restriction in the line or a kink. This might also explain the running rich issue and hard on gas as a block or restriction in the return line seems like it might increase the fuel rail pressure.

 

[jaydaniels]

That doesn't make any sense because the return into tank has nothing that would restrict it.

After looking at the part schematics I noticed that the fitting on the tank for the return line is actually a check valve. I assume this is a one way valve so that fuel can only flow into the tank and not back out. Could this valve actually be bad or stuck partially closed? Problem seems to be the worst while sled is idling or when cylcing fuel pump before startingn which would be when the 'most' fuel is actually trying to return to the tank.

 

[FLYBYU]

Check it. You should be able to blow through it

 

[Yamadog]

The check valve is what regulates the pressure through the rail if it is stuck or frozen shut you will build to much pressure whether the sled is driving, idling or the key is just turned on which activates the pump. I had one on an o6 RTX that was also bad.

 

[jaydaniels]

The check valve I'm talking about is not the one on the rail but the one on the tank where the return line goes in. The fuel line that is leaking and blowing off is the return fuel line which is after the fuel regulating valve. See the link. Its item number 12.

http://www.yamaha-motor.com/sport/parts/home.aspx

 

[FLYBYU]

Sounds like it's stuck. I have heard of it before. take it off, make sure your tank is lower than it or you'll have fuel everywhere. Take an air line and gently try to blow through it.

 

[jaydaniels]

I guess that didn't work, Here is the picture or schematic.

 

[jamesc]

The check valve is what regulates the pressure through the rail

NO it does not the component numbered 13 on the fiche slide INTAKE 2 is the regulator and is what controls the rail pressure. you are correct though if for some reason the check valve is restricted, stuck closed it will act the same as if the regulator is faulty.

i was going to mention possible issues in the return line but not being experienced wasn't aware they have a check in there. aside from the check having a problem in the return is really a strange problem.

yes Jay you're understanding it correctly now. if you're blowing off the return line then the restriction whatever it is, is downstream of the regulator. as mentioned you should be able to blow through the check valve. while all the fuel lines from and back to the tank should be designed to handle full deadhead pump pressure the engineers might have saved $$$ by using lighter plumbing on the return. personally not a place i would cut corners, fire is a formidable opponent. BTW i would keep an extinguisher handy while fixing this problem.

 

[jaydaniels]

Great thanks for the help jamesc. I'm going to check the valve as soon as possible. Hopefully that's the problem. I can't think of anything else that it could be.

 

[kinger]

A quick way to check that is pull the hose off it put it in a container and start the sled, fuel should come out at a fairly slow pace. I forgot to hook mine up one time and it didn't gush out of there like a fire hose like I thought it may.

 

[jaydaniels]

A quick way to check that is pull the hose off it put it in a container and start the sled, fuel should come out at a fairly slow pace. I forgot to hook mine up one time and it didn't gush out of there like a fire hose like I thought it may.

Great idea. That may also rule out the check valve going into the tank as the problem. Won't be able to take a look until Friday night. Anyone else ever have this issue??

 

[jaydaniels]

Well, the check valve going into the tank was the issue. It was stuck in one position. Just partially open. Haven't rode yet but we will tomorrow and will report back on how the sled works. People should really keep this part in mind as a troublesome spot. This sled was running rich, hard on gas and had a stumble at idle that almost caused it to quit. I think this little issue may have caused a lot of problems.

 

[FLYBYU]

If you go to a front mount kit with a mod tank it doesn't come with one

 

[jaydaniels]

Not sure what you mean by a front mount kit. On another note thanks everyone for the help on this one.