Gas tank always sucks air when opening

[d9103365]

My gas tank always sucks air hard when I open the cap. I know this will happen once in a while...but its happening a lot on my car...could this indicate a problem with the gas tank or cap? Isn't it supposed to have a way of releasing the pressure?

 

[sleepar]

I ran into that when I changed caps my 67 is vented only at the cap... I like the non vented cap for storage.... but I switch to my old cap for driving around... you could drill out the cap with a small drill for a vent 1/16"

 

[Hemi Rebel]

[video=youtube_share;2WJVHtF8GwI]http://youtu.be/2WJVHtF8GwI[/video]

 

[sleepar]

In was more worried about the fuel pump diaphragm... than my tank...

 

[65hemi]

Tank needs venting.

 

[Seax440Dodge]

I'd be more worried about a couple hundred dollar fuel tank that's a pain in the *** to change than a $30 fuel pump that's a 10 minute swap

 

[sleepar]

I didn't realize the fuel pump can suck a tank flat.... I went through a full tank and it was hard to get the cap off but it didn't crush the tank....

 

[70redbee]

Does your tank have a vent line? Check the cap for any damage and that you have the correct cap, some caps are vented, some are not. If you have a vent line, check to make sure it is open, could be closed due to dirt, rust or spiders and insects.

 

[67 coronet]

67 tanks are only vented by the cap.new caps dont cut it at all.they say they are vented,but none of the ones i got would vent.just drilled a couple small holes in the cap.

 

[nm9stheham]

You can get a vented cap to fit. It will be made so that it is less prone to pull in dust/dirt than a non-vented cap with a hole drilled in it.

My dad lost the cap on his '64 Dodge wagon and put on a wrong (non-vented) type. Went down the road and a while later 'pooom!', the suction pulled the tank bottom in. It did not fully collapse the tank but he lost several gallons of capacity.

 

[sleepar]

I've put a quarter between the stant locking cap and the seal and it will stay there for a vent...

 

[383man]

I cut a small slot in the rubber seal on the inside of the gas cap to do the same thing just to be sure it vents. Ron

 

[gdennis400]

I had the same problem on my 77 Cordoba, after i purchased a locking gas cap. I found that if i put a small cut in the cap seal, that provides enough of a vent to keep the vacuum from occurring.

 

[sleepar]

A 77 should have a vent to a charcoal canister.... but some times a fuel filter will work with a goose neck on the line if the canister is gone or shot...

 

[383man]

I did not see anywhere where he states its a 1977 car ? Even if it was then it would have a press/vacum cap. Ron

 

[gdennis400]

I don't know what to say, but that was an issue I had on my vehicle after I purchased a new locking STANT gas cap.

 

[d9103365]

My car is a 75...and yes it does have a vent line that goes to a charcoal canister. All of it (canister, hoses, etc) seems to be intact and looks good from the outside. I noticed that filters for this canister can still be purchased at rockauto. I don't know if that would help or not...or if the line is plugged. My fuel gauge doesn't work either so perhaps this is all linked?

 

[sleepar]

I did not see anywhere where he states its a 1977 car ? Even if it was then it would have a press/vacum cap. Ron

I was close.... by 2 years ron.. lol. I've been around a little...
Anyways you have to replace all that old junk you can and probably the sender and mabe the under dash voltage due hicky thing... good time to clean the tank and what ever else... its a lot easier said than done.