HELP please! Au fairmont fuel problem.

[slywag]

I've got an au fairmont wagon,
Runs beautiful on gas but won't run
On fuel Just splatters until revs are roughly 2800-3000 rpm
(It struggles getting the revs up)
Won't drive at all on fuel.
Backfires occasionally when starting to if that
Means anything?,
Fuel pump is working fine,
Fuel filter is fine, stumped on what it could be?
Have half a tank of fuel,

Any help would be appreciated!
Cheers.