Venting gas cap
 

Went to change my in line fuel filter and fuel was pouring out. Not good. that fuel could get past my carb float valve and into the oil. Have a Strat locking cap. Decided to drill a small hole somewhere in the cap. But wait!!! There is a gasket on that cap,I removed the gasket,problem solved. There is a flap in my tank neck to keep the fuel in and a somewhat seal w/the cap. The idle seems to be more regular and I think I may have improved my mileage.1984 K20

Re: Venting gas cap
 

Thanks for sharing that info I think I will try this as well. I have my vent tube blocked off because when I used a 3 line fuel pump it kept flooding so I went back to a 2 line pump. I felt like the tank needs to be vented

Re: Venting gas cap
 

The tanks DO need venting. On early pre-emission tanks, the vent was a short piece of hose ending in a plastic vent of the type used to vent rear end differentials. The hose hung off the end of the 2nd pipe out of the sender unit.

A non-sealed gas cap may lead to gas leaking out on acceleration. These long tanks have a large 'slosh' factor.

Re: Venting gas cap
 

Alot of folks eliminate the charcoal canister under the hood thinking it is robbing HP. I think the entire purpose of the canister is to vent the gas tank and capture the fumes. Then, when the engine is started, it sucks the fumes into the engine air intake.

Maybe look to see if the canister is hooked up or clogged?

Re: Venting gas cap
 

To add to what Jay said, around 70 the canister was added and vented caps went away.

Re: Venting gas cap