Topic: Gas tank pressure
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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I have noticed a lot of gas tank pressure when opening a nonvented gas
cap. Is this normal for a 71 ? Could that little valve on the left side top be
plugged or evap cannister be piped wrong? Its enough pressure to blow
any dirt away that has accumalated at filler neck.
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It may well be the vapor return check valve on the top left of the fuel tank.
Non-vented tanks will build up some pressure normally, but it should dissipate once it sits for a few minutes. You may want to remove the hoses from the tank, the canister, and the vapor return valve and see if any are restricted.
I had this issue on the '85...it was building up enough pressure I was a-skeered it was gonna blow the tank apart! I found the hoses from the canister to the tank were all stopped up. Once I took the air hose to them, and blew all the crap out, the problem went away. If you do this, just make sure the hose is open on both ends, so you don't blow any trash into the tank, or any other components.
Non-vented tanks will build up some pressure normally, but it should dissipate once it sits for a few minutes. You may want to remove the hoses from the tank, the canister, and the vapor return valve and see if any are restricted.
I had this issue on the '85...it was building up enough pressure I was a-skeered it was gonna blow the tank apart! I found the hoses from the canister to the tank were all stopped up. Once I took the air hose to them, and blew all the crap out, the problem went away. If you do this, just make sure the hose is open on both ends, so you don't blow any trash into the tank, or any other components.
Joel Adams
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Thanks Adam, I'll try that tomorrow. I did try blowing into that vapor check valve when I had the tank out and it seemed OK. I mean it was working in one direction only. I did'nt think to blow the lines out from the cannister to the valve. If I don't have a lot of pressure aftre 24 hrs do you think it is
OK? Mike
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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