Chevrolet Repair: I cant put gas in my car., pressure release valve, vent valves

Question
I'm having trouble fueling my car. I've been to 4 gas stations and none of the pumps will fuel my car, they keep clicking, the gas station dude said my car had a really bad problem. The gas pumps have systems that won't release fuel when it recognizes this problem. Please tell me this makes since.  

Answer
Hi Lysa,

One gas station, possibly could have a 'sophisticated system', but I never heard of it.  4 gas stations, absolutely not.  There is no problem that these pumps can 'recognize'.  A gas pump is not much different than a garden hose.  

Now what is the problem?  You have a plugged vent.  It could be an actual plug, or a bad vent valve.  I don't know what kind of car you have, or what year it is.  But newer cars have vent valves that release pressure from the tank.  All cars have a filler tube vent.  Any of these could be the culperet.  That you need to look into further.  

The reason the gas won't go in is pressure.  The gas pumps do have a pressure release valve that triggers when the back pressure comes up the filler tube.  When you put in the gas, the air in the tank must leave.  If it can't, it will back up the filler tube.  When you fill up your tank, and the pump handle clicks off. This is the pressure coming up the filler tube, because the gas level is higher than all the vents.  In your case, the gas pump handle thinks your tank is full.  

If you put the pump handle spout in the tank filler hole just enough to make the gas not spill out, and pump slow; you may be able to slowly fill the tank.  The pressue coming up the filler tube, can release all around the pump handle spout.  

You need to get the problem fixed.  If the gas doesn't go in, once you tighten the gas cap, you may not get the gas to come out and supply the motor with fuel.  Just as the air must leave the tank to make way for the gas, the air must return to replace the gas you burn.  If air cannot get into the tank, vacuum will cause your car to not run. If your car stops and won't start, trying releasing the gas cap.  With the cap off, the car should again start.   

Good luck.

C J S