Evening,

While cruising tonight at ~50mph, I noticed that my truck would not accelerate. I mashed the throttle to try and move over three lanes to get off the road and the truck shuttered some, backfired a couple times and then accelerated slowly. While pulling into a parking lot, the engine finally shut off completely.

Now engine will turn over normally, but will not start. I haven't had time to do any diagnostics other than reading the trouble codes. P0171 and P0173.

2002 F150 XL 4.6L 4x4 220k mi

Any ideas?

 

Also, the truck now shakes badly while cranking.

 

Fuel filter? Fuel pump? Any fuel pressure? Inertia switch tripped? Just brainstorming.......

 

Go check fuel pressure with a gauge. You probably have little to none.

 

I have never really messed with with fuel sysrems before. Cam you walk me through this process and what results I'm looking for? I know I am getting some pressure, bc I depressed the schrader valve while cranking and did have fuel spay all over me.

 

fuel pressure gauge, hook it to fuel rail and turn engine over...

 

I get that part, but what am I looking for as far as pressure?

Btw, sorry for the poor spelling. My phone has a mind of it's own.

 

You probably need 28 psi to start it.

 

you're looking for a min of 30psi...cycle the key on and off, ( not all the way over to start) several times, note to see if the pressure slowly increases or changes in pressure.

when was the last time the fuel filter was changed?

with p0171 you may have a vacuum leak too....so look those over carefully too.

also...make certain that your air filter is in good shape and the MAF sensor is clean

 

Thanks. The fuel filter has around 15k on it. At work right now so I can't do much. I did notice that I can't seem to hear the fuel pump come on with key turned to run. I can hear what sounds like a solenoid clicking on and off, but not the buzzing of the pump.

 

So as expected, my fuel pressure is exactly 0. Is the fuel pump the most likely culprit? I'm kinda short on time, so I'm tempted to just go buy a fuel pump and hope that fixes it. Any fuses or relays that are known to go bad?

 

There is a fuel pump relay, on my '97 it's under the hood. I believe you can switch out the horn relay to check if it's bad. Also check all fuses just to be safe. If not a fuse or relay, the pump has probably crapped out.

 

Changed fuel pump, truck started right up. FYI, if you have a body lift, you can get away with not pulling the bed or fuel tank. I just unbolted the front strap and loosened the rear one. Rested front of tank on a cinderblock standing on its end. That gave me just enough clearance to swap the pumps out.

Thanks for the help.