Gas Flow

[scootermcq]

I'm not seeing the trees for the forest here....

Neighbour's bike is gravity fed to the carbs.

If I open the drain, the gas will flow out the drain and gas will feed from the tank to the carbs so I know the floats are working and nothing is blocked. If the bike is running it will use the gas in the fuel line but nothing comes from the gas tank to replace it and it starves out.

I have taken the cap off the gas tank, so I know it's not a vapour lock or something in the tank.

I'm a little stumped as to why gravity is broken. Anyone have any ideas?

[enforcer]

I'm not seeing the trees for the forest here....

Neighbour's bike is gravity fed to the carbs.

If I open the drain, the gas will flow out the drain and gas will feed from the tank to the carbs so I know the floats are working and nothing is blocked. If the bike is running it will use the gas in the fuel line but nothing comes from the gas tank to replace it and it starves out.

I have taken the cap off the gas tank, so I know it's not a vapour lock or something in the tank.

I'm a little stumped as to why gravity is broken. Anyone have any ideas?

Does he have a vacuum petcock? If so, the diaphragm gets trashed if you turn it off and try to start it.

[scootermcq]

No, it is not a vacuum petcock. I wondered if I missed that, but gas flows great to the carb if the engine is off, so that rules that out.

[enforcer]

No, it is not a vacuum petcock. I wondered if I missed that, but gas flows great to the carb if the engine is off, so that rules that out.

Are you sure it's starving out? Could be the float level is set incorrectly and it's using what's in the bowl and not refilling.

Or, the float bowl vent is blocked.

[scootermcq]

Or, the float bowl vent is blocked.

I was thinking about it some more and I would bet you pounds to a pinch of pig poop that the vent is plugged.

[WintrSol]

You didn't mention what bike you are dealing with; it could make a difference.