Tank pressure

[tumblingtwerp9]

I have a yamaha superjet. I have a leak on one of the fuel pumps. I pulled the on line and it shot gas every out the end of the line. I think the tank is pressurising too much so my question is should I be able to blow throught the check valve on the vent line both ways? and how much pressure should the tank have?

 

[#ZERO]

The check valve one works one way to let air in the tank and if the tank is holding pressure, it's working normal.

 

[yamaslut]

I have a yamaha superjet. I have a leak on one of the fuel pumps. I pulled the on line and it shot gas every out the end of the line. I think the tank is pressurising too much so my question is should I be able to blow throught the check valve on the vent line both ways? and how much pressure should the tank have?

it wouldn't be a check valve if you could... one way only.

 

[tumblingtwerp9]

ok so its not the check valve. Do you guys have any idea what could be the problem? the carbs were rebuilt this winter. diaphragm?

 

[Matt_E]

I have a leak on one of the fuel pumps

the carbs were rebuilt this winter.

I'd say something went wrong in the rebuild.
Take it apart and pay close attention to where all the parts, seals, and gaskets are.
Use the Mikuni manual as a reference.

 

[tumblingtwerp9]

I'd say something went wrong in the rebuild.
Take it apart and pay close attention to where all the parts, seals, and gaskets are.
Use the Mikuni manual as a reference.

Ive rebuilt plenty of carbs and I was pretty sure it all went together right but i guess that is the next step. Gotta pull the motor again.:doh:

 

[norcal ex]

What Matt said...

Also, did you pull the line right after you rode it or a while after? the tank will pressurize as it sits due to the temperature and such. If you pull that line it would shoot fuel all over the place.

 

[stanton]

Ive rebuilt plenty of carbs and I was pretty sure it all went together right but i guess that is the next step. Gotta pull the motor again.:doh:

pull the motor to work on carbs?? u crazy!

 

[Matt_E]

x2, why do you have to pull the motor to get to the carbs? :dunno:

 

[tumblingtwerp9]

What Matt said...

Also, did you pull the line right after you rode it or a while after? the tank will pressurize as it sits due to the temperature and such. If you pull that line it would shoot fuel all over the place.

I ran it on the hose cause I noticed gas in the bottom of it and after i ran it i pulled the on line and it spewed gas everywhere. So it was right after running.

 

[tumblingtwerp9]

pull the motor to work on carbs?? u crazy!

x2, why do you have to pull the motor to get to the carbs? :dunno:

It has an R & D manifold and I cant get to the nuts that hold the carbs on. Any ideas on a way to get them off without pulling the motor?

 

[Matt_E]

I have yet to see a manifold that I can't get the carbs off with the engine in the hull.
I believe that includes the R&D manifold.
Use a short wrench and patience.

 

[tumblingtwerp9]

I have yet to see a manifold that I can't get the carbs off with the engine in the hull.
I believe that includes the R&D manifold.
Use a short wrench and patience.

I might just try pulling the fuel pump with the carbs on. idk :shrug:

 

[Matt_E]

By the way, what makes you sure it's the fuel pump that's leaking?
Are the hoses on the carb nipples tight, with zip ties or hose clamps?
It should be normal for gas to come out of that line if it was just ran. There is a bit of head in that line, and suction will keep it going.

 

[tumblingtwerp9]

I can wipe the gas off the bottom of the pump and within a few seconds the gas is back. I dont know what else to check.

 

[Matt_E]

Okay, makes sense then. I thought you saw the gas at the bottom of the hull.
So what is the difficulty with that manifold? Are you having trouble because the spacing between the two inner studs is so small?

 

[tumblingtwerp9]

There was a bunch of gas at the bottom of the hull since i ran it yesterday as well.
Im not sure what the problem with the manifold is Ill see if I can get the carb off later tonight.

 

[Matt_E]

The two outside nuts should be very easy to get off.
For the two inside nuts, use a short wrench.

 

[augustaf]

It has an R & D manifold and I cant get to the nuts that hold the carbs on. Any ideas on a way to get them off without pulling the motor?

I sawed off a 10mm wrench, welded it to a 1/4" drive and then use a 1/4" breaker bar which lets it flex a bit. I use tweezers to lay the nut up against the stud and get it started by pushing against it with a screwdriver.

 

[tumblingtwerp9]

I replaced the fuel pump gasket and its still seeping. any ideas? Im out of them.