Auxiliary fuel tank breather

[Craig M]

Am adding an auxiliary fuel tank to my 95 Yukon. The existing fuel tank appears slightly under pressure when we remove the fuel cap. Should I vent the auxiliary tank. Just an open line up to a high point? I am not going to have a fuel return line back to this tank.

[rjwest]

I tied the aux filler vent to main filler vent
Both get same pressure, I did not use the
AUX tank set up per GM.


Only problem, Need to NOT xfer fuel just before trying to fill aux tank. vent retains some
fuel and will not vent AUX tank, won't take fuel.