85 F150 Backfire through Carburator

[jfoster5150]

I have an 85 F150 when it first starts it runs fine revs normally drives good....however once it warms up it starts to sputter and backfires through the carb and wont rev when you stomp the pedal it will only get to about 2000 rpms...any suggestions will be greatly appreciated and I replaced the carb because the old one dumped fuel into the oil pan so its been replaced........

[Winddrifter]

Interesting problem. Very possible that you have a vacuum leak. Try partially blocking the air path into the carb and see if it runs better. If it does, that confirms it has a leak.
Check all of the vacuum lines including the vacuum amplifier to the brakes. Get a can of WD40 and spray it along the edges of the intake manifold where it meets the head and see if the engine rpm increases. If it does it probably has an intake manifold leak and will need an intake gasket change.
Have you checked the timing?
Maybe the EGR valve is not operating properly?
Good luck,
Windy
(Winddrifter)

Originally Posted by jfoster5150

I have an 85 F150 when it first starts it runs fine revs normally drives good....however once it warms up it starts to sputter and backfires through the carb and wont rev when you stomp the pedal it will only get to about 2000 rpms...any suggestions will be greatly appreciated and I replaced the carb because the old one dumped fuel into the oil pan so its been replaced........