I read an article that flex fuel fords will adjust the mixture program to adjust for a failing fuel pump and you have to put a guage to it to monitor the low speed pressure and high speed pressure, a tell tale sign is the inferred flex fuel percentage, on norman gas it should be less that 15 percent, my truck is showing 83 percent. i reset the kam this morning and i am going to drive it to see what it shows when it relearns. the scanner shows it has 58 lbs but i am not sure that it measures real time, as the pump is a modulated pulse duty pump. google "finding flex fuel faults"
and you will see an article at Auto Service World by David leduchowski, read it and see what you think. also this link https://www.ford-trucks.com/forums/1...1-6-2-a-3.html
David

 

I'll look into all that later today. I haven't checked fuel pressure because Ford chose to omit a simple test port on these trucks as you well know. I've thought of buying an adapter, I probably will, but it irks me when they leave off something so important for simple diagnostics. It's like Chryslers and their lack of transmission dipsticks. I have to read trans temp with my scanner and measure fluid levels....dumb dumb dumb

 

i ordered an adapter today otc 310-d252 suppose to fit it. I also found a video showing how the pump could be failing and yet show max pressure here it is.
2012 Ford Expedition Max Limited, Fuel Supply Video - iATN

 

Mine is showing 53.8% flex fuel, I'm currently running 0% so that may be an indicator!

While running my fuel pressure reading on the app shows %, but it may mean pressure, I have no clue. Whatever the unit, it shows 33 while at idle and very low throttle then partial to full throttle it jumps up to 48. Here's a graph showing the stumble as it reads on the fuel pump:


Heres another showing the fuel pump on startup. Key on, engine off reads 75, then the first few seconds of running it shows 48 then drops to 33 after a few seconds.

 

I gotta say, I'm on about two dozen forums and this one is without a doubt the worst mobile friendly I have ever seen. Let me try adding the pics here since editing my last post turned into a total cluster cluck.

 

g i would bet your toolbox that you need a fuel pump, i am leaning the same way, if you watch the video you will see what i mean and if you read the link on this forum i sent that is what it took to fix his truck. I am going to do a test on mine tonight and will let you know I reset the kam so it could relearn the fuel content and if it shows high that means it is trying to compensate for fuel volume not the pressure.
David

 

I'm thinking the same thing, I might go ahead and order one tonight and see if it works. I found out that an old friend has changed jobs and now maintains a fleet of 6.2 trucks for the oilfield. He said the common issues he sees are cracked Y pipes and fuel pumps dying around 80-100k miles, (depending on hours, of course)

I'm only at 54k miles, but I might as well try it, worst case scenario is I end up with a spare used fuel pump!

Thanks for the continued involvement, talk soon.

 

i am leaning to the same thing, i found lots of problems with pump volume messing with inferred flex fuel content.
David

 

Well updated info, short story it is fixed, replaced the fuel pump and module. Long story, the new system is a 2 speed pump and at cruise you are running on the low side which is pulse modulated and when the pump get weak and cannot deliver the volume it causes the truck to surge and to switch back and forth between high and low, the key in diagnosing this was the inferred flex fuel percentage, before i replace the pump it was 83.52 percent after replacing the pump and clearing the KAM the new valve was 1.2 percent, the system was trying to increase the pulse on the injectors thinking it was ethanol fuel and that is what cause the rich condition in the morning when it first started, the truck now starts great like it should, also as a bonus the fuel mileage has gone up about 2 mile a gallon.

 

That's great news, thanks for the update! My pump is on order, should have been here today, but I guess the snow delayed it?


At any rate, I really appreciate you sharing your experience and helping with this. I'll update in a few days and let you know if the fuel pump solves my issue as well.

thanks,
George

 

Do you have the part number for the control module? I decided to order it as well and I'm seeing drastic price differences and it seems the part changed somewhere around 2011 so I'd like to order the correct part. I would stop by the dealer, but it's 116 miles to the dealer and I really don't feel like spending half a day to drive to the dealer and back!

Thanks either way.

G

 

We really appreciate you following up with all the details. This is a great learning experience for all of us. As these trucks get older, we will start seeing more issues like this, and when people follow up, it allows us to help others down the road.

 

part numbers for the pump motorcraft PFS-600 Ford BC3Z-9H307-D the module is AU5Z-9D370-J.
Hope this will help someone else, I spend a lot of hours and testing to find this problem, I would have never guess a fuel pump in the beginning the way the truck ran, it pulled hard to redline with out cutting out, but the two speed fuel pump i think is going to be a problem down the road.
David

 

Thanks again David. I should have my pump and module swapped out by mid week and then I'll report back how it worked on my truck.

 

Hopefully I'll get the pump swapped out tomorrow. I tried dropping the tank today, but Ford didn't give access to the lines nor enough room to reach them without removing the exhaust and/or driveshaft. Tomorrow I'll pull it out of the shop and remove the bad and go that way. I don't have room to remove the bed in the shop and it's damn cold outside so I really wanted to do it by dropping the tank. I didn't do it earlier because it's been as cold as -33F this week up here. Now the temps are back up in the 20's so I'll get it done tomorrow.

Oh well.