i have a 1987 f150 with the 4.9l motor. when driving if im going at 30-40 mph and push the gas down, the truck shutters and almost dies. the speed decreases?????? what could be the problem? i changed the fuel filter yesterday and the truck is running a lil better but is still shuttering

 

the truck has duel tanks and the front tank does not work. i was told it would be wise to change the both pumps(inline and in tank) and possibly fuel lines. when i changed the fuel filter the gas that leakes from the filter was dirty with quite a bit of sediment.

 

Check fuel pressure, I suspect you have a bad fuel pump. If you have dual tanks, you actually have three fuel pumps. One in each tank(low pressure pumps that provide fuel from the tank to the main pump) and one on the frame rail just under the driver's floorboard. It could possibly be the tank pumps not supplying fuel to the main pump. Does it run better on one tank than the other? I would (on experience, I would likely say it is the in-tank pump that is the problem.

Robbie