Hey guys,

New to this forum but have been searching the internet for many days now trying to figure out what happened to my truck. I have read all the posts (I think) on similar issues but have not found a solution.

Short background history:
- 06 Ford Expy King Ranch
- Bought last year Feb at 165k miles
- Always dealer maintained and I'm the second owner

- Just drove from PA to TX without any issue.
- Felt slight stutter at idle and figured the fuel filter needed replacement.

Okay, here is where it gets interesting. I will walk you through my process of changing the fuel filter, in case I messed something up there.

- Jacked up the car.
- Pulled fuse 12 (fuel pump) and started the car to drain the lines.
- Got under the truck and pulled the cover plate from the fuel tank.
- Removed the old fuel filter, and replaced it with a new one (made sure the flow direction was correct).
- Put the car back on its wheels and plugged fuse 12 back in.
- Turned the key twice to charge the filter and started the car up.
- Drove 30 yards and "ENGINE FAILSAFE MODE" popped up in the dash and had the well known limited power.
- Hooked up my scan tool and I had more codes than I ever saw in a car that was fine before a simple fuel filter replacement: P1000, P0020, P0102, P0135, P0155, P0443, P0446, P2106, U1900

So here I get confused. How could a fuel filter do that to the car. So the next day I redo the process but when putting the filter back on pre-charge the filter with fuel to prevent a potential vapor lock (not likely to happen, but I had to do something different). Cleared the codes and started the car. It ran great. Took it for a 35 mile drive with 3 stops (engine off for several minutes while in a store). Parked it overnight. Next morning again ENGINE FAILSAFE MODE within 30 yards with the same string of codes.

So I get back under the car and now also clean the TB and the MAF. Under the car I found that the Electronic Fuel Module had a corroded backplate so replaced that with an new unit as well. Again cleared the codes (even did the hard reset by disconnecting the battery neg and cross wire it to the battery pos for a minute).

After starting the car from cold I let it idle for about 15 minutes so it could relearn its idle throttle position settings (read that online somewhere). Took it for a 4 mile drive at city speeds, then a 30 mile drive on the highway. Truck ran like a champ - better mpg than ever before. Parked it overnight. Next morning, you guessed it, ENGINE FAILSAFE MODE.

At this point I am starting to get to the end of my solutions. On the freeze frame readout of my scantool I suddenly notice that my MAF has a zero readout. That can't be right. So I grab my multimeter and check the wires on the MAF sensor. And indeed my red/yellow has no power. The gray/red has the 5V but the rest of the wires are dead. So I check the fuses (32 and 34) and relays (201 and 203). All seem to be good and running the needed 12v on both ends.

So here is where I am at. Does anyone have advice for me other than bringing it to a dealer for diag?

Thanks in advance.

 

Based on the codes you've posted which basically say there's a loss of power to sensors, EVAP controls, and a loss of Buss communications, I'm leaning toward your fuse 32 not making a good contact, the fuse box itself having an issue, or the ECM going bad. There's an outside chance of some wires having been worn through and grounding out, so you could try inspecting every portion of the harness you can see.

 

BTW, fuse 12 not 32 was the fuse to pull to kill power to the fuel pump.

 

Hi Alloro,

Thank you for your response. Yes - I see that I made a writing error I did indeed pull fuse 12 for depowering the fuel lines. I checked fuse 32 and 34 for defects since those are the ones that the PCM and other big components run off.

I will do some more investigating on the suggestions that you gave. Thanks again for the advise.

 

However, have you ever heard of something like this happening right after swapping a fuel filter when the truck was running basically at 98% good prior to the swap? It just seems so strange to me that there are wire issues that are unrelated to the filter swap.

Is it possible that the truck was running on some sort of memory setting and got scrambled do to the change in filter psi, wanting to get new readings but couldn't due to a pre-existing wire issue?

I am trying to wrap my brain around the cause and effect of the filter swap giving me these problems. Any suggestions to alleviate my hurting brain?

 

You were already having issues with how the truck was running and that's why you swapped the fuel filter. The fuel filter might not have been the problem. The problem could still be the fuse box since you tugged and pushed on that when you took out the fuse.

 

True enough - I was feeling a light stutter at engaged idle and had the feeling I was missing some torque. I will do another analysis of the fuse box and connectors and see what I can come up with. Thanks again for the help.

 

Well Alloro,

You were pretty much on the money with your call. Turns out one of the wires (red/yellow) had partially come out of its connector above the fuse box. That made for a partial current of 1.8v instead of the needed 12v.

Pushed the wire back into the connector and voila - truck running like Swiss clockwork.

Thanks again for the help!

 

Hmm, that's weird...I wonder how the wire got pulled out in the first place. Oh well, at least it's fixed.

 

Ya - honestly it puzzles me too. Its not in a spot where the passengers feet could get. So how this got pulled or even vibrated out, beats me...

 

Maybe the wire has been like that for a while and was the source of the stuttering, and now you've found it.

 

Yep - that's what I am thinking. The truck runs beautiful now doing 17mpg city and 21mpg hwy. That's a lot better than it has ever done since I got the truck.

Below I put some pictures of my truck ... Hope you like'em