Vapor Lock

[magoconnor]

Hello. 

I could not start my scooter yesterday.
I tried everything but a tire iron.

I have removed the vaccum fuel delivery system, and gone for straight hose.

Finely I popped the gas tank open, and I could see gas running through the lines.
Then fired right up.. 

There is a few air bubbles in my fuel lines, but the no start was defintely do to a vapor lock. 

My svooter is equiped with gas tank vent just below the lit.
Its a hose with a canister attached and some more hose. 

I figured the canister might be backed up, so I've tried blowing it with compressed air.

The air can only travel one way, is this normal ??

Hose directly off the tank :  No flow through to the other side. 

Hose after the canister: The air travels all the way to the other side. 

[kagetenshi]

The easiest way I can think of to fix this issue is to drill a very very small hole in the gas cap. Something like 1/16 of an inch. That should solve your problem. And that canister is more or less a carbon filter to help catch any gas vapor escaping the tank, just another California epa thing.

[magoconnor]

Okay, cool.

But wont the gas not just vaporize and escape?

[kagetenshi]

If it's used regularly it won't be an issue. Most gas cans are vented to prevent a pressure build up during storage.

[greginisn]

There are plenty of instructions available via Google regarding the GY6 fuel vapor canister removal. I agree it was just a feel good item for the EPA and btw it isn't even found on newer scooters. Gas tanks have to breathe or goofy things happen.

Greg

[FrankenMech]

A 1/16" hole in the cap will work. To keep water out of fuel tanks I usually just file a small groove in the gas cap sealing surface.

[GrumpyUnk]

The tank must be vented in some fashion or the fuel will not be able to flow out to the float bowl.

Check by disconnecting the fuel line and allowing fuel to flow into a catch can/container. If things are working properly, fuel will flow from the fuel line, full diameter, at full speed, as long as there is fuel in the tank. If the flow is slow or restricted, try removing the tank cap. If flow improves, more venting is needed, or the current vent system needs investigation. Some have vacuum operated vents that capture fuel fumes into a charcoal filled canister, then release them after engine start into the intake manifold. Check for vacuum valves connected to the fuel tank vent. If you attempt to disconnect or bypass the vacuum system, be sure the vented fumes can escape freely and don't form a 'pocket' where a combustible mixture should concentrate. If you catch yourself or scoot on fire, I accept no blame... Be careful.
tom