Gas tank venting

[WZ JUNK]

I am continuing to have problems with the my 54 chevy with factory TBI.  It does not set any engine codes but it develops a miss after driving it some time.  Everything is factory from an older Caprice.  Even the gas tank and fuel lines, But I eliminated the charcoal canister.  I do have a check valve on the fuel tank so that as the gas is used, the tank will not become a vacuum.  Lately when I fill the tank, there is a lot of pressure that vents when I remove the gas cap.  I am wondering if something is going on with the pressure in the tank that is causing a problem.

John

[kb426]

How about you loosen the cap as an experiment? Am I correct in thinking that all the older tbi systems are of the low pressure style of around 15psi? Is there a chance that the pump is way too large causing the aeration and subsequent semi vapor lock of the system? As I have been aware, the obd1 and obd2 systems only throw codes related to emission failure so if something outside those parameters occurs, you won't get any codes with a conventional reader. A real GM diagnostic tool would be required for further diagnosis.

[WZ JUNK]

How about you loosen the cap as an experiment? Am I correct in thinking that all the older tbi systems are of the low pressure style of around 15psi? Is there a chance that the pump is way too large causing the aeration and subsequent semi vapor lock of the system? As I have been aware, the obd1 and obd2 systems only throw codes related to emission failure so if something outside those parameters occurs, you won't get any codes with a conventional reader. A real GM diagnostic tool would be required for further diagnosis.

I agree.  I am going to connect my diagnostic tool and use my phone to take screen shots when I am having a problem.  Maybe I can detect something.  Thanks.