Chevrolet Repair: Fuel Tank Vent Valve, code emissions, pollution control system

Question
We have a 2004 Blazer that wont take gas.  If you put it in a gas can it takes about 20mins to get 5 gallons in it.  If you use a regualr pump the gas comes back out.  We have heard it might be the vent valve.  Do you know where it's located and if this can be done on your own.  I appreciate any help you can offer.
Brandi

Answer
Hi Brandi,

It is the vent valve...most likely.  When you put gas in the tank, it pushes out air that is in the space the gas is taking up.  If the air cannot vent, the gas cannot go in.  

The valve is located on top of the tank.  It vents to the charcoal canister.  It should throw a code.  Emissions has caused cars to vent gas fumes to the pollution control system.  But if this is plugged filling with gas, it should also be plugged emptying.  You should experience pressure differences in the tank, enough to trip a code.  

There is a rig up method to fill the tank, or you can get it fixed correctly.  To rig it: go to a parts store; buy a gas rated small hose (1/4" or so)about 3 feet long; take cap off and feed the hose into the tank, leaving a little bit hanging out (so you don't loose the hose into the tank and can get it out); then fill the tank.  The tank will vent out the little hose.  Don't let the hose get under the gas level.  You need to be above the gas level.  This will get you by until you get the thing fixed.

Hope this helps.

C J S