Gas leaking from filler cap!!

[TommyBoombotz]

Hello everyone, some basic info right off the bat. I have a 1987 R10 305 TBI with a TH400 transmission, dual fuel tanks. Lately Ive had a problem with fuel coming out of the passenger side filler. After the car warms up after a few minutes, the fuel level gradually starts rising up the fuel neck, and then pours out from under the gas cap. As of right now, it only happens on the passenger side.

Some steps I have taken, so far.

1. Removed the gas cap altogether, and let the truck idle. Gas still leaks from filler.
2. Removed the line from the tank to the canister under the hood. Gas still leaks.


Any help at all would be great. As of now, I cant drive the truck, and the weather is starting to get nice.

Appreciate your time,

Botz

 

[1985c20]

I'd look at your tank switching valve. Maybe its pulling fuel off the drivers side tank but returning to the passenger side tank.

 

[Charlie]

 

[gotyourgoat]

There seems to be a rash of dual tank issues going around.

This truck was pushing fuel to the cap and beyond.
https://www.gmsquarebody.com/threads/fuel-vent-issue-stumped-need-help.25231/
Selector was the issue.