Gas Fumes-1990 Q45

[Q45denver]

I'm getting a lot of pressure buildup and gas fumes from my tank. Condition appears mainly during warm weather. When I take the gas cap off, after awhile, the engine stalls. There is a noticeable breeze coming out of the tank when I loosen the cap and with the cap on the pressure builds up to maybe 40PSI. Has anyone had this problem and what was the fix? There are no driveability problems or engine lights but the fumes give me a headache. Fortunately its been fairly cool recently-with five feet of snow Wednesday.

[Q45tech]

Designed that way to create a positive pressure in the tank to force fumes into engine compartment gas vapor cannister where they are metered into plenum to burn..........Denvers altitude [low atmosperic presssure] creates problems for all cars thats why you have special gasoline with different Reid Vapor pressure.

[Q45denver]

The gas vapor pressure could be part of the problem, but in the many years I've owned this car I never noticed gas fumes coming out of the filler cap and never had such extreme pressure buildup- even in mid summer. The gas smell is noticable even when I'm a considerable distance from the car and definately comimg from the gas filler. This leads me to believe that something must be constricted and a potentially dangerous condition. Can I test the system by pulling the hose going to the throttle body to see if there is positive pressure? If I can't locate the problem I may just remove the canister and plug the lines. Just had the emmisions inspected so I'm OK for a couple years and can always reinstall. Thanks for your help.

[maxnix]

I'd say check your cannister to ensure it's not clogged, or even full of gasoline. Proabaly a bad line or connection somewhere.