So a few days ago the family and I were on a road trip. After driving for close to three hours we ran into a problem. We were doing about 75, which is about 3000 rpms with the 4.6L, When we dropped from 3k to about 400 and started to lose speed. I pushed the gas peddle all the way to the floor and no response at all. I pulled over and it had a very rough and choppy idle and it wanted to die. It eventually did. I checked all fuses with nothing found and i even hit the fuel pump shutoff reset. It started back up no problem and we got about 5 miles before it the exact same thing. Idle at about 400 rpms and no throttle response at all. I shut it off and called a tow truck. It started up and they drove it onto the back of the tow truck and off at the local mechanic. They spent 2 whole days trying to diagnose it and even drove it for 4 hours straight, no issues. They pressure checked every system they could and tested every sensor they could. They could not find a single thing wrong with it. I drove it home 3 hours away with no issues. I got home and let it sit for about 10 minutes before I had to leave. I didn't make it more than 2 miles before the same issue popped up. I pulled over. Shut it off for 15 minutes and it started right up and drove home.

It threw 4 codes.
1. Pressure control solenoid malfunction
2. Fuel pump Primary circuit malfunction
3. Gear 3 ratio incorrect
4. Gear 4 Ratio incorrect

I've had 2 mechanics tell me its a PCM issue. Any other ideas or fixes?
Thanks everyone for the help.

 

RPM's sound too high for 75mph, unless you were driving in 3rd gear.

not quite as familiar with the explorer, but if it has a fuel pump driver module, i would suspect that for the fuel problems. on other models they corrode and cause issues like you describe.

i would say the two transmission codes are separate from the two fuel codes. you likely have two things going on at the same time, but are not related.

 

Now that I look back I was probably closer to 80 or 85 at those RPM's. I had a third mechanic look at it. He thinks its a faulty fuel pump that is overheating and shutting down. He based this on the fuel trims constantly being out of whack. He said the three tranny codes are because it lost power and signal in the powertrain. I replaced the fuel pump less than 10k miles ago so it's possible its just bad?

Any more ideas? Thanks again everybody.

 

The bushings in the fuel pump may be worn causing the pump to lose rpm,s. It will slow to where it will not provide enough pressure to run above idle.
When you cut the engine off the pump will cool and run normal at the next start up for a while then do the same. It will keep getting worse.
I had this problen some years back.

 

wouldn't be the first-ever bad fuel pump out of the box -- it happens.

that said, i'm not pulling the tank and doing it again without being pretty dern shure the pump is actually bad.

time to get a fuel pressure gauge on the fuel rail and see what you have.

 

I taped a fuel pressure gauge to my windsheld and drove around for about an hour one day and it fineally started fluctuating and the engine skipping. That will be the best way if you can find a way to get it attatched to the fuel system.

 

We did the fuel pressure gauge test. Kept perfect pressure the whole time. I had my mechanic come over and reset the KAM. It's been entire tank of gas so far and no issues yet. Is it possible it ended up with a corrupted "file" in the memory?

 

It also shifts a lot smoother now too. I hardly even notice it anymore.

 

spoke too soon. Did it again to me today. Different codes this time.

1. Random misfire detected
2. Cylinder 1 misfire
3. improper switching bank 1 sensor 1

I did notice something else. All three times its done it I've had more than half a tank of gas, and it's always been on a day I've put more gas in.

A co worker of mine had a vehicle that did something similar. It kept getting thrown into "Limp home mode". IT turned out to be a wiring harness that was worn through.

Any thoughts?

 

How many miles and how much time after you got gas did it act up? Just wondering if you have a bad (plugged) fuel tank vent system. If you used enough gas to develop a vacuum in the tank, maybe the fuel pump is getting starved. It's kinda far out there, but you could check by taking off the gas cap next time it happens and see if it alleviates the problem. The tank would draw air in rather than push it out.

 

I had the same thought. That was actually the first thing I tried every time its happened. Its no set amount of miles. The first and second time were about 180 miles and about 3 hours afterward. This last time was like 30 miles and about an hour afterward. Ive been doing some research online and found people with similar problems and it turned out to be MAF and throttle position sensor. Thoughts on that?

 

PROBLEM SOLVED!!!

So after a new computer and a new transponder ring( it was throwing PATS codes too), it still was doing it. Random intervals, but always on hot days. We started to get what sounded like boiling fuel.

We went ahead and changed the fuel pump. Due to a manufacture defect one of the wires to pump inside the tank had worn through to bare wire. This in turn kept shorting and shutting down the pump. It also startred to melt the other wires. New pump unit went in and no more problems.

The pump was a Delphi. Now I know many will say use motocraft only, as were told by all 3 of our mechanics, but turns out that Delphi makes Motocraft, so same pump anyway. Interesting info as well, Ford used Airtex pumps from the factory.

I hope this will help anyone else in the same situation.