fuel tanks sucking
 

on our 1987 GM K2500 we have replaced the fuel tanks, fuel gauges with pumps and the fuel selector on the frame as well as the switch in the dash as well as the wiring.
problem now is that the fuel when sitting in our garage will siphon out of the drivers side take and over flow the right side tank. when we move it out doors this stops??? There is a lot of vacuum when the cap is opened and leaving the cap loose it still makes it way over. I do have the vacuum canister plugged off under the hood.
Has any one else had this problem or heard of this and what to do to correct it. thanks

Re: fuel tanks sucking
 

Couple of questions... Did it do this before all the changes, or is that why you did all the changes?? Could outside temp vs garage temp have something to do with it??