elwayfan

I have and '87 F150, at take off, it starts to bog down like it is starving for gas. it also starts again when I hit between 80 - 100 kph. I have changed the fuel pumps, fuel filter, air filter, coil and cat. I have also checked the plugs and cap, and they are all fine. What else should I be looking at?

bcmontgomery

You need to do a compression test and need to see if the timing may be slightly off. Also make sure it is shifting properly, could act like this if it is starting in 2nd and shifting to 3rd early.

transmaster

check the accelerator pump in your carburetor, best thing is to ether rebuild what you have or get yourself a rebuilt carburetor.

bcmontgomery

Ya probably in the carb, I forget everything isn't fuel injected.

elwayfan

there is no carb and could it be plugged pipes before the cat?

transmaster

You are correct it has fuel injection, I can never remember the transitional years on Fords. So forget the accelarator pump it doesn't have one. It however it still going to be in the fuel delivery system.

I checked things out and The 5.0L V8 switched over to fuel injection, first as an option in 1985 and then altogether in 1986.

Fast Hampster

I suggest to measure the fuel pressure and post the results in here. I guess that it's really not getting enough fuel

elwayfan

Is there an known problem with a loud humming noise comming from the front fuel pump on the rail? I have noticed that when the noise is there the truck starts to bog down on me. I have changed the pump 3 times, and I still get the noise from the pump.

Just call me Sean

iTrader: (1)

My pump is loud when it is trying to pump gas but there is none to pump. I run my truck out of gas a lot. There must be a hole in the line inside or outside the tank before the external fuel pump causing the pump to lose it's prime. The in tank pump may not be working well or the small gas reservoir on the frame rail may be leaking and emptying itself out, starving the external pump for fuel. There also may be a clog in a line.

wde3477

The noise could be a failing pump, or a pump being starved (inlet) or restricted (outlet) - none of which are healthy. The only time you should really hear the pump, if at all, is when you roll the key to On before Starting.

IIRC, your model year should have a low pressure pump in the tank - if so, are you sure it is working? Also, may have the fuel pickup screen in the tank blocked.

Since you've already changed the cat - doubt that there would be other exhaust restrictions. Not to say there isn't - just would put it lower on the list of probabilities.