2004 Chevy Cavailier won't start right after filling up with gas

Car won’t start after filling up with gas. I have tried a new fuel filter, new gas tank cap, checked for pressure on fuel pump. We have gotten
it to start (but barely) when either hit gas tank with hammer or shake the back of the car, otherwise you have to set and wait 15-30 minutes before it will start and when it does it smells very weird (like it’s flooded but an extra strange smell with it). I have seen a similar posting on here and someone suggested it might be a purge value problem. In talking with someone at auto store they didn’t think this was the issue. I do have my check engine light on all the time and when checked the code , it said oxygen sensor. My two other Cavaliers have also had the oxygen sensor problem but it never did this with that code.
Please if anyone has had this issue, or know the answer I would appreciate an answer so much!!!

Do you stop filling as soon as the pump clicks off? Or do you keep filling while trying to top off the tank and round up to the next dollar? If you do, that can cause gas to flood the charcoal canister that scrubs the gas vapors coming from your tank while you fill. Which in turn will damage the canister and cause problems. Not sure if it’s related to your problem, but worth asking since you mentioned gas.

Next time this happens, disconnect the purge vacuum line at the intake manifold and cap the nib. See if the engine starts okey now. If the engine starts, reconnect the purge line and see if the problem returns.

I am wondering if the Onboard Refill Vapor Recovery system is allowing raw gasoline into the vapor recovery canister and it is being sucked into the intake. This should not happen unless the purge vacuum solenoid valve has been damaged so it is leaking all the time.

Hope this helps. Let us know what you find.

It does sound like an evap system problem of some kind. Purge valve is the most likely, but there could be other problems in the evap system that would cause this symptom too. Could be a hose is plugged up or has split and fallen off where it should be. If you leave the gas cap loose, will it start then? That would be a clue. It could be a fuel pump on the fritz problem too, and the tank refill process puts some extra back pressure on the pump or something, changes something enough to trigger the fuel pump to lock up. Are you certain the O2 sensor is the only thing showing up in the ECM codes? There could be an O2 DTC, and an evap DTC too. Someone trained to read the codes wouldn’t miss the second one, but somebody who doesn’t have the experience using the scan tool might. Who’s reading the codes for you? Maybe Google “Chevy Cavalier evap system”, you might find some ideas there.

it starts when banging on the gas tank . . . the pump may be failing

Has anybody checked the fuel pressure with a gauge when it’s not starting?

where is the purge vacuum line? Yes we have checked the pressure, it was 55
thanks everyone for commenting


Does the pressure hold after shutting the car off?

I don’t know if the pressure holds after shutting the car off, the auto shop just said it had 55 lbs.


If the pressure doesn’t hold after shutting the car off, there will be problems starting

OVRS…Onboard Vapor Recovery System. All newer cars have it. When you fill the tank, the vapors in the tank are directed into the carbon canister and after you start the car, a purge valve opens and the trapped vapors are purged from the canister and burned…Sometimes, the plumbing fails and the tank vapor is directed directly into the air intake during fueling, flooding the engine and causing difficulty in starting…