fuel starvation/petcock ????

[vwbuge]

Just had the carbs rebuilt and then tuned. Drove it to work one day last fall and came out to an empty tank of gas and a huge puddle under the bike. Beat on the carbs a few times and refilled gas tank. Ran good after that. Sitting in the basement the wife smelled gas and freaked out. I removed the tank and let it sit all winter. I hook it back up now and it won't run with the petcock on "ON". Seems like it is starving for fuel. When I turn it to "PRIME" it warms up and runs great. After it gets warm I turn it back to "ON" and it seems to starve for fuel again.

Any ideas?

[mark]

Pull your vacuum line (the smaller of the two hoses running out of your petcock), turn your petcock to "on" and suck on it. Fuel should flow from your petcock. If not, your petcock needs to be rebuilt or replaced.

[vwbuge]

I'm sitting here thinking. Maybe I have them hooked up wrong. There is a line going from the tank fuel gauge to the smaller port on the petcock and then the larger line runs from the petcock to the carbs. Is this correct?

Thanks for the quick reply.

[mark]

I'm sitting here thinking. Maybe I have them hooked up wrong. There is a line going from the tank fuel gauge to the smaller port on the petcock and then the larger line runs from the petcock to the carbs. Is this correct?

Thanks for the quick reply.

Nope. The hose from the fuel tank guage vents to air. You've got a vacuum port on your carb that connects to the petcock. If this is your '78, it would be the port on the #3 carb.

[vwbuge]

I checked it out. There are vent lines from the top of the bowls on #2,#3 and #4 carbs. Couldn't find any other vent lines. I freed up the gauge line and hooked the vent line from #3 carb to the petcock. Everything seems fine now.

Thanks!

[badbrown]

Remove the petcock from the bike. Make sure the filter is still on it. On old bikes sometimes the previous owner breaks off the filter. Clean out the filter, but make sure not to disturbed the diaprhagm if yours has one.

[earlfor]

The nipple on #3 is for a vacuum line and connects to the small (1/4") fitting on the petcock. The fittings/nipples on #2 and #4 are vent lines and are open to atomsphere.

E.

I checked it out. There are vent lines from the top of the bowls on #2,#3 and #4 carbs. Couldn't find any other vent lines. I freed up the gauge line and hooked the vent line from #3 carb to the petcock. Everything seems fine now.

Thanks!