Vapor Valve Leak?

[grnhays]

I took the car out yesterday, and noticed a strong gas smell during idle. I checked the top lip on the tank, it wet, from gas.

I dropped the tank today. Thank god the tank was almost empty. Looks like the leak was coming from the vapor valve Seal. The rubber grommet for the vapor valve Seal was cracked, all over. I thought it would've been the fuel pump seal.

When I was dropping the tank I noticed the hose coming off the Vapor Valve was pinched flat, between the tank and the body. I can't find a carbon canister on the car, anywhere. So not sure if this was done purposely?

So now the question. Would the cracked, Vapor Valve Seal, be the cause of the leak? Would the pinched Vapor Valve line, cause the leak? Seams like a strange spot for a leak, seeing how the vapor valve sits higher than the fuel pump.

 

[jrichker]

Someone probably plugged the vapor vent line up near the missing carbon canister. Normal pumping the tank caused a vacuum which probably collapsed the vapor vent line and caused some of the damage to the seal.

Here is a description of the vapor vent system.
Charcoal canister plumbing - one 3/8" tube from the bottom of the upper manifold to the rubber hose. Rubber hose connects to one side of the canister solenoid valve. Other side of the solenoid valve connects to one side of the canister. The other side of the canister connects to a rubber hose that connects to a line that goes all the way back to the gas tank. There is an electrical connector coming from the passenger side injector harness near #1 injector that plugs into the canister solenoid valve. It's purpose is to vent the gas tank. The solenoid valve opens at cruse to provide some extra fuel. The canister is normally mounted on the passenger side frame rail near the smog pump pulley.

It does not weigh but a pound or so and helps richen up the cruse mixture. It draws no HP & keeps the car from smelling like gasoline in a closed garage. So with all these good things and no bad ones, why not hook it up & use it?


The purge valve solenoid connector is a dangling wire that is near the ECT sensor and oil filler on the passenger side rocker cover. The actual solenoid valve is down next to the carbon canister. There is about 12"-16" of wire that runs parallel to the canister vent hose that comes off the bottom side of the upper intake manifold. That hose connects one port of the solenoid valve; the other port connects to the carbon canister.

The purge valve solenoid should be available at your local auto parts store.

Purge valve solenoid:

The carbon canister is normally mounted on the passenger side frame rail near the smog pump pulley.
Carbon Canister:

 

[grnhays]

The canister and solenoid, are no longer in the car. I found the remnants of the plastic tubing, inside of the passenger side fender.

I ordered a new Vapor valve seal. I think ill plug the vapor valve at the tank. I can't see myself spending $150 for a canister and solenoid.

Hopefully the new seal will stop the leak.

 

[jrichker]

You need some way to vent the tank. It does not have to be a carbon canister, but it does need a vent. With no vent, as gas is pumped out of the tank the volume above the fuel increases. That causes a vacuum to form which will tend to reduce the effectiveness of you fuel pump and can cause vapor lock. If you don't do anything else, either get a vented cap or drill a very small vent hole in your current fuel tank cap.

 

[grnhays]

Quick update on this problem. The issue is fixed. After installing a new sending unit, gaskets and hold downs, and plugging the vapor valve seal. I came home to find it leaking worse.

I dropped the tank again, which I'm getting good at . Tightened the hold downs a bit more and got a new vented gas cap. No more leak. No more crazy pressure in the tank when I take the gas cap off. Most importantly, no more leaks! Thanks jrichker!