The fuel filter on Ford "Returnless" fuel system has a return line, so it will have a check valve inside, I would replace the filter if it hasn't been replaced in the last 5 years.
As far as the symptoms, maybe you are leaking fuel into the intake from an injector or Damper.
This could cause Flooded Engine after a half hour or so.
But just after shut down leaking fuel would evaporate fairly fast in warm intake so no flooded engine after 5-10 minutes.
And after sitting longer, overmight, fuel would also evaporate.
Damper is at the end of the fuel rail, near firewall, it has a vacuum line attached.
Remove this vacuum line and check it for fuel, there should be no fuel or fuel smell.
After driving it home from work or ??, shut off engine and remove air plenum(big air tube) from intake.
Give it 20-30 minutes then open throttle and smell intake for gas smell, there should be none.
All fuel injection computers have a Clear Flooded Engine routine
Turn on the key
Press gas pedal all the way to the floor and hold it down
Last edited by RonD; 10-19-2015 at 06:08 PM.