Just recently bought a 2002 Blazer and the seller informed that it was difficult to fill he with gasoline. He had changed the filler neck/pipe but that hadn't solved it. Searching here I found that the Vapor Canister Vent Valve could be the problem. I have checked it and it isn't clogged. I went on and disconnected the vent tube coming from the tank to the vapor cannister and then filling it with gas worked as expected. My conclusion is that the canister is clogged and needs to be replaced.

Question, when I'm at it should I change the vent valve at the same time when I'm at it?

Thanks

 

The tank is vented from the tank > sometimes a rollover/check valve at the top of the tank > the tube on the way to the cannister > cannister > the tube to the vent solenoid > vent solenoid. Any one of these components can be restricted, including the pipes/tubes and the check valve if used in your truck. A tank that will not fill can of course also be related to the fill tube which can have a anti-siphon/rollover ball valve as well as you discussed. A couple of thoughts:

Proper analysis can avoid the parts cannon and the first step with this problem is what you did - take the entire vent circuit out of the equation first and see if that solves the problem.

Make sure that its not the pipes/tubes.

I would leave the vent circuit disconnected for a few fills and make sure that you don't have an intermittent problem.

I don't like replacing perfectly good AC Delco OEM parts with potentially inferior aftermarket parts which can fail quickly, unless its a maintenance item that should be replaced. This is complicated of course by components that are hard to get to that you will have in your hand during a repair like when you drop the gas tank.

George

 

I had the same problem on my 2004 Avalanche. First I replaced the vent valve and it made no difference. Then I replaced the charcoal canister and that did the trick. of course you need to make sure the electrical part of your purge valve is working properly.

 

I have now replaced the canister and it swallow gas like it should.