Gas tank vent?

[DMC3165]

If it is jammed or not workkng properly. Would that block the flow of vapors to the canister and could it cause my fuel tank to pressurize?

[Ron]

If it is jammed or not workkng properly. Would that block the flow of vapors to the canister and could it cause my fuel tank to pressurize?

Contrary to several posts in this thread, it is a closed system -- It is supposed to pressurize!
To answer your question, it's possible but very unlikely. But more important, if the roll over valve, its hose from the tank, the vent tube, or hose connecting it to the canister is stopped up, it can cause the tank to collapse. Normally the system "vents" both ways, vapors to be burnt when a purge signal (vacuum) is sent to the canister, and, allows air to enter the tank to replace the space occupied by fuel as it is consumed (to prevent it from collapsing), but, ideally, NEVER to the atmosphere.

Take another look at the link I posted above, (here is a better diagram http://store.delorean.com/c-275-2-4-...l-systems.aspx ). Follow the vent path (from filler to canister) and make sure all are clear, bbut don't leak. Check the orifice in the cold start valve air tube and other things mentioned on the following pages while you are at it... If you haven't double checked the boot, as David suggested, I would, while you can smell the fumes...

[kings1527]

Was there any followup or solution to this thread? I'm having the exact same problem. Tank pressurizes when the tank is maybe 1/2 full or less and vapors are coming out of the fuel cap (which I know is good) and eventually through the air vent and stinking the cabin.

Things I know are good is the check valve, vacuum lines are clear, carbon canister appears to be ok and has a blanking cap on it. All vacuum connections appear to be tight but I'll confirm vacuum is coming from the line going into the engine underneath the W pipe. I do have Hervey's silicone vacuum lines on my car and I'm not sure if something weird like the diameter is off but I'm trying to think of everything.

I wouldn't mind bypassing the carbon canister by joining the two vacuum lines together and double checking to make sure that's not the problem. But for a pretty simple layout, I can't figure out the issue.

[DMC3165]

Was there any followup or solution to this thread? I'm having the exact same problem. Tank pressurizes when the tank is maybe 1/2 full or less and vapors are coming out of the fuel cap (which I know is good) and eventually through the air vent and stinking the cabin.

Things I know are good is the check valve, vacuum lines are clear, carbon canister appears to be ok and has a blanking cap on it. All vacuum connections appear to be tight but I'll confirm vacuum is coming from the line going into the engine underneath the W pipe. I do have Hervey's silicone vacuum lines on my car and I'm not sure if something weird like the diameter is off but I'm trying to think of everything.

I wouldn't mind bypassing the carbon canister by joining the two vacuum lines together and double checking to make sure that's not the problem. But for a pretty simple layout, I can't figure out the issue.

Way to resurect an old thread! I sold the car two years ago. But what I can tell you is the tank itself was the problem. Upgrading to the DMV improved fuel pump (modified AC Delco unit) helped alot because the original style would keep popping out. Assuming it was an over pressurized fuel tank causing this problem is what started this thread. In my case the tank opening where the fuel pump sat was slightly deformed and would constantly leak and eventually the fuel pump would just pop out. What was weird when the tank was full you'd never smell anything only when it was around half or less and when it was hot outside it was even worse. I never got around to totally fixing it but a new tank or a ton of silicone might have solved it.

[David T]

Read my post #14. Also you could have a bad gas cap or even a wrong one. First place to look is the inner pump boot to see if fuel is pooling on top of the fuel pump. Make sure the fuel sender unit is not leaking also.