i have an '04 mazda3 and every time the fuel tank gets to 1/4 when i add gas i can't start my car unless i push the gas pedal. it happened once when i fueled the tank full, too. i'm thinking it's the fuel filter but i'm not sure. any suggestions??? thanks.

 

The no start only happens after you have added fuel to the tank? Ran across a similar problem last spring that turned out to be a evap canister purge solenoid valve stuck open. Should also be causing check engine light to be coming on with evap leak codes or fuel trim limits reached. Have had a few problems with fuel pump check valve allowing fuel to drain back into tank from injectors but that would just create a long crank time before starting and would usually have to sit for at least an hour or so.