Why would I have large amount of pressure in tank when I take off cap. It seems to interfere with starting. I have replaced cap. Is it bad two way on tank or some censor somewhere. I replaced the fuel pump some time ago had no pressure, running 42psi now. shortly there after car wouldn't start. Jacked it up removed cover at lines on tank disconnected vent line to fill neck checked that not plugged. Car started with vent off ran fine. re connected line ran for day or two then back to not starting. Was fixing to introduce it to mister tannerite. took gas cap off lot of pressure car started after few tries. Been running last two days.

About ready to let my teams practice extrication drills on it. But my daughter needs a car, engine has less than 30,000 miles on it decent car.
any help would be appreciated

 

Vehicle information please.

 

Are you sure it's pressure and not vacuum?

I second the request for car information.

 

92 Accord 2.2. it was pressure. Happen to be in right spot on a warm day and seen vapors. from other threads i've read seems to be somewhat normal.

The biggest problem I'm having is hard starting. It will start then it fumbles around a little bit like no fuel, you touch gas just a little and it will smooth out and get on down the road no issues. Will still do the starting thing even after it's run a while. Touch gas and off you go. I drove this thing for couple of weeks myself. I gave this car to my daughter this weekend thinking I would keep looking into starting issue. Put it on trailer and delivered it. No other issues just the starting. My grandson gets in I tell him what to do, he starts it just as i said backs off trailer runs couple minutes shuts off. I go to leave she has to move car I tell her how won't start. Find out she pumping gas while starting. Could this be a TPS issue? Does it have a calibration. None shown in my book. 2 days later still no start. Any ideas?

 

Purge valve or solenoid, or bad Two way valve.

Possibly a damaged carbon canister(when the tank is overfilled too many times,liquid fuel will flood the canister and vapor lines)

Pressure build up is normal. Excessive build up is a problem. The Two way valve is responsible for relieving the pressure in the gas tank. The pressure is relived into the carbon canister.

Disconnect the lines at the canister and look for fuel. There should be no fuel or wetness of any kind.