Gas leak!

So today I had to work on my Jeep thermostat and after disassembly discovered I would not be able to reuse the gasket. Not problem, I'll bundle up and ride the bike to the auto parts store. Got ready to go and started it up and noticed gas shooting out the back of the petcock, pulsing with the vacuum from the carb. I took the tank off and tightened the four screws to squeeze the gasket more but it didn't slow the leak. I haven't searched yet but is the gasket replaceable by itself or would I need some kind of rebuild kit? Picture shows the leak spot.

 

Seal kits are not expensive & available on EBay, search for fuel petcock repair kits. Photo shows what mine looked like, when it's pulled apart the black seal will be stuck to the solid wafer insert. To install the new seal pull the thin black membrane free and draw through the large hole in the wafer.

 

Thanks. I see the leak is not at a gasket but the thick block that looks yellowish.

 

if you gotta take it off you may as well rebuild it

 

DO NOT BY FROM EBAY SELLERS!!!!

Many kits are not correct for the application.

Buy from @chacal.

Proper parts, guaranteed.

Rebuilding the Yamaha Vacuum Fuel Valve w/pics

 

The thick yellow block is the wafer, sounds like that will need replacing

Hey at least I didn't suggest Amazon!

 

Rebuild kit from LEN.

if you have gas on the vacuum side, your diaphragm is ruptured.

in the meantime, after your bike starts, switch to PRI. That bypasses the vacuum part of the petcock. Just remember to turn it back when you shut you r bike off (just in case you have any leaky fuel valves that you don’t otherwise know about)

 

Thanks for the tip allowing riding until fixed, Dave.

 

Well, with the petcock set to prime, gas still pulses out in rhythm with the vacuum. Detaching the vacuum line and plugging it results on fuel running out in a steady stream on prime. No way to ride it until fixing or replacing. Anyone got an old working one for sale for replacement instead of rebuilding?
Emptied the tank and pulled the petcock. Will take a close look later.

 

Hmmmm. I think it should be bypassing the vacuum circuit. Let me see if I have one for the 700

 

Huntchuks, give me a call
Dfox

 

Dan, when you switch to PRI, you still had fuel squirting—— I just had a thought.....you need to disconnect the vacuum line and cap the port on the intake boot And probably plug the vacuum port on the petcock. That will completely disable the vacuum. The fuel should then flow around through just the PRI free-flow passage. Just remember to reset to ON or RES when you’re not riding.

of course, if there’s been catastrophic fail of the diaphragm, or plunger, or other parts inside, then I guess fuel could flow anywhere regardless of selector position or vacuum.