Pressure Buildup in Gas Tank?

[Emgeem]

It's been about 10 years since I last drove my 85 LWB, and have a question. Is it normal for the fuel tank to pressurize when the motor is running? I swapped out the manual fuel pump with a Holley Red and my tank is building up pressure after running the motor. When I did the swap I just connected the supply line to the carb to the pump. I have eliminated the under hood canister and what I assume is a return line. None of the lines are plugged intentionally they are still running up the frame to where the manual pump was. I don't remember if the tank used to pressurize back when the truck was my daily driver. Is this normal or do I need to vent the tank somehow?

 

[TheGolem]

IDK the answer, but I would like to know too. I just bought an 87 V10 suburban silverado, and I feel the pressure come out when I take the cap off to put gas in it.

 

[Georgeb]

You absoluteley need to vent the tank! Reinstall the canister and reconnect the vent line. Is your new pump correct for not having a return or pressure regulator?

 

[bucket]

You really don't need to have the canister, you just need to make sure the vent line that went to it is clear.