My 94 F150 has went to crap all at once and I need some help. Tired of replacing everything. It has a new EGR valve and sensor, new front O2 sensor, plugs, wires and TPS. When I crank it up, it sounds fine, and if you apply the gas easy it sounds fine, but if you press on the gas fast the engine shutters like it is about to die. I put a scanner on it which came back TPS (which I just replaced) and code 624 and rear O2 sensor. I can't seem to find the rear O2 sensor and what is the EPC and could it be anything else, before I have to tear the tranny pan off? Any help would be great, another week without my truck stinks....

 

How long since fuel filter was changed?? Have you checked the fuel pressure? Seems like it might be fuel related since the ignition parts are new. What about cap and rotor?

 

yup i agree...also check your fuel pressure regulator..take off the vacum line on the top and if gas drips out your diafram is shot

 

It has been a while since it was changed, I did change one of the filters, but had some trouble with the one that is against the side wall. Do you have any tricks to getting that one off. It is the one in the back below the bed, like right by the rear tire. I don't really have a way to check the fuel pressure unless you something about how to check that two. I am a female, but very mechanically enclined.

 

Regarding the vaccum line on the Fuel Pressure Regulator, I don't want to assume, so do I take it off with the truck not running or running?

 

One other thing I meant to mention is, when the truck is idling and you press the gas hard and it starts that shuttering, the OD light on the gear shifter starts to blink (not in a series for a code, just a steady blink), that is why I thought the EPC.

 

Okay, I tested the Fuel Pressure Regulator with the truck running and not running and there is no sign of gas or smell of gas there.

 

the way to test the fuel pressure is u need to have the tool for it (can buy at a car parts store) and you screw it on to the schrader valve (kinda looks like a valve stem on the fuel line) i not exactly sure but it should be around 40-50 psi on start up im not sure about running (maybe 32psi) Also maybe you should try to clean your fuel injecters??

 

First thing I'd try is running some Sea Foam or something of the sort in the fuel to see if cleaning the fuel system helps. Also, as mentioned above, make sure you have proper fuel pressure and such.

If that doesn't help and the fuel pressure checks out, then with the engine idling try spraying something like carb cleaner around the intake (upper and lower) and trottle body gaskets. If you do that and the engine revs a bit, then you'll need to replace the intake gaskets.

If you spray carb cleaner around the intake and the idle doesn't change, with the engine idling try pulling one plug wire off at a time to see if there is a change in idle when the wire is removed. If you find one that doesn't change the idle, I'd do a compression test on that cylinder.

 

Okay, did the fuel pressure check, it has about 60 psi. I changed the fuel filters, ran sea foam through it, changed out the distributor cap, rotor button and distributor. New idle air control and still nothing. I have checked for vaccum leaks and don't have any. What else could it be? I just don't understand how it can idle fine all day and glently reave it up and be fine all the way to red line and if you press the gas harder (not stomping it) the engine just boggs down and then the OD light on the shifter comes on. Give me some more guys!