Hey guys, hopefully someone has some suggestions for the problem that I just started having with my truck. First the current stats: 05 FX4, 5.4, K&N FIPK, Edge tuner on Transmission only tune, Magnaflow exhaust, 4.56 gears, 35" tires.

Within the last few days I have been experiencing an intermittent hesitation and bucking problem that comes on suddenly. When this happens, the truck feels like you are holding the throttle wide open, and turning the ignition on and off in 2-3 sec intervals. Shutting the truck off and immediately restarting it does not clear the problem, but if it sits for a while it might not do it for another day or two. I set the Edge to display the fuel rail pressure, and while it is bucking the fuel pressure is everywhere, dropping to zero, then up to 70, then leveling out to 30, then repeat the cycle. When it is running fine, fuel pressure is maintained between 38-41psi all the time.

The bad thing is that it is not throwing a check engine light. It just acts like it is running out of fuel in 2-3 sec intervals. At first I suspected fuel line freezeup (it has been -5 here in PA for a few day), so I put a bottle of HEET in the tank during fillup, but it didn't help. I then replaced the fuel filter with a Motorcraft replacement, but still no luck. Could the fuel pump be going? I've had fuel pumps go out, but usually when they quit, they are done, not this random intermittent crap.

The really weird thing is that about 3 weeks ago, I got a random check engine light when I started the truck up. It started fine, but I pulled the codes anyway. It had 3 codes: fuel rail pressure sensor failure, fuel pump driver failure, and fuel pump failure. It ran perfectly at the time, so I cleared the codes and they have not came back again. Now that I am having a problem, NO CODES...

I'm at a loss right now as to what the problem is. If I trust what the codes say from 3 weeks ago, I'd have to replace the entire fuel system. That seems illogical that everything can go bad at one time. Any suggestions on how I should go about narrowing down this problem?

Btw, truck is out of warranty.

 

early 05's are notorious for injector problems? but if you were getting fuel problem codes a few weeks ago it may be the pump or even crappy fuel?

 

Mine is actually a late 05, built in March '05. It has had multiple tanks of gas through it since it threw the codes weeks ago. I always fill up at Sheetz gas stations, a large chain supplier here in PA. I fill up my '77 F150 at the same spot, and have has zero issues with it. My family also uses the same gas station (06 Scion TC, 00 LHS, 95 F150) with zero issues.

Anyone ever had a pump go bad intermitently? Like bad today, fine tomorrow?

 

Ok, so I tried to drive home last night but it was bucking and stalling again, so I called a buddy with a trailer to come and pick me up. While I was waiting for him, I ran a diagnostic with the Edge and it came up with a code saying that the fuel pump driver module was offline. I did some searching through this site and found a few threads where people have had the driver module bases rust out, allowing water to get into the module and short the circuitry, which then causes the fuel pump to run out of control, causing erratic fuel pressure fluctuations. I'm going to drop the spare tonight to see if I can locate the module, hopefully that is the only problem.