loss of fuel during startup

[Anonymous]

hi y'all
My '80 gs850g seems to have a short term fuel leak during first start for the day. The fuel seems to come from the airbox.
Could the fuel tap and needles be at fault ?

I separated the fuel tap, now (after inspection and re-assemble), the fuel pours out ( of the tap ) like no tap is in place . I may have assembled it incorrectly -- not sure..

the tap is a vac.operated with positions prime - on - reserve
any advice would be appreciated

[earlfor]

Re: loss of fuel during startup

Prime position bypasses the vacuum function and lets gas gravity flow regardless of whether the engine is running or not. If your selector is set to prime and gas is flowing from the fuel tube of the petcock, that is normal. Run and reserve are vacuum activated. The engine must be running to activate the diaphram which opens the petcock allowing fuel to flow. If your selector is in either run or reserve, the engine is not running and fuel flows, then you have assembled the petcock incorrectly or the "O" ring on the diaphram plunger is not sealing. You did reinstall the internal spring between the diaphram and the cover plate?

Earl

hi y'all
My '80 gs850g seems to have a short term fuel leak during first start for the day. The fuel seems to come from the airbox.
Could the fuel tap and needles be at fault ?

I separated the fuel tap, now (after inspection and re-assemble), the fuel pours out ( of the tap ) like no tap is in place . I may have assembled it incorrectly -- not sure..

the tap is a vac.operated with positions prime - on - reserve
any advice would be appreciat
ed

[Anonymous]

thanx earl, I will check those points you mentioned / spring is in place .. thanx

[earlfor]

OK, if the spring is in place, when there is no vacuum present it will push the plunger into the inlet tube. The plunger has an "O" ring on its end, so if it doesnt seal, the "O" ring is done for or the spring is not "springy" anymore.
That really is the only possibility for fuel flowing regardless. If fuel does not flow with the engine running and vacuum present, then it would be a leaking diaphram. I think all you need is an "O" ring.

Also, even if the petcock leaks, the 2nd failsafe in the system is the float needles. If they seal as they should, fuel would not overfill the float bowls even though the petcock is faulty. I suspect the four "O" rings that fit under the float needle seat/fuel inlet are also dried out and hard resulting in the float needle not being able to seal. You shouldnt need to replace needles and seats, just the "O" rings.

Earl

thanx earl, I will check those points you mentioned / spring is in place .. thanx

[Anonymous]

no doubt about you Earl, you hit the nail on the head
The "O" ring attached to the diaphram seems to have been at fault.. of course, now, I'll have to tend to those in the carbs as soon as I can.

Thanx so much mate...........greatly appreciated


Stayt upright

[earlfor]

Glad I got to spend some of your money. :-)

Cheers

Earl

no doubt about you Earl, you hit the nail on the head
The "O" ring attached to the diaphram seems to have been at fault.. of course, now, I'll have to tend to those in the carbs as soon as I can.

Thanx so much mate...........greatly appreciated


Stayt upright