Fuel Cock Settings??

[lmari]

1979 GS1000...

If I set the fuel cock to "ON", the bike will run, sputter and die.

If I set the fuel cock to "RES", the bike will run, sputter and die.

If I set the fuel cock to "PRI", the bike will run normally but when you turn the bike off, it will leak gas.

So I've been storing the bike in the "ON" position, it doesn't leak gas, and then when I wanna ride I put it in the "PRI" position.

Did I hook it up wrong when I re-assembled?? From the reading I've found, its a vacuum based system so when the bike is set to "ON" no fuel can flow but why does it not get fuel? I've also read that it could be bad for the motor to start it from the "PRI" position cause fuel is flowing freely to the carbs and sitting there.

Any help is appreciated!

[tkent02]

Sounds like the petcock is not opening correctly when the engine is running. Is the vacuum line leaking? Could be the diaphragm is leaking too.

[tom203]

Get a new petcock, but this stuff...


"If I set the fuel cock to "PRI", the bike will run normally but when you turn the bike off, it will leak gas."

if it starts leaking right away, sounds like your float needle seats are tired- they should be able to hold back fuel for awhile.

[tkent02]

Get a new petcock, but this stuff...


"If I set the fuel cock to "PRI", the bike will run normally but when you turn the bike off, it will leak gas."

if it starts leaking right away, sounds like your float needle seats are tired- they should be able to hold back fuel for awhile.

That depends on where it's leaking from. Leaking from the float bowls, or the overflow tubes, you're right. Leaking from the petcock? Leaking from the fuel line down to the carb or from the fuel T? If the fuel T is leaking, if it's the plastic one with built in seals, let it soak in gas for a while, it may swell up and stop leaking. If it's the metal one, replace the o rings.

To answer the OP's questions, the fuel line from the petcock, the fat one goes onto the fuel T between carbs 2 & 3. The vacuum line, the smaller one comes from the nipple on the left side of carb #3 to the smaller nipple on the petcock. The nipples on carbs #2 and #4 are just float bowl vents, they have no vacuum and won't turn on the petcock. Check all of these lines for cracks, splits or hardened ends that cannot seal.

[lmari]

I changed the o-rings already from the guy on this forum. It does hold back fuel for a while and then it starts dripping from the tubes, I can take some pictures. It doesn't leak from the fuel cock.