That’s a lot of rain! Think I’d have pushed it into the shop.

 

Full update later.

All that work, no change.

Gold spring at idle.

Less than 1/2 throttle, 2200rpm in 2nd.

 

Have the flex lines between frame hardlines to the engine hardlines that run up to the fuel bowl been replaced before?

 

nope.

fuel pump is on order.

 

Check the current fuel pump directly at its outlet to see what volume it is capable of. It may be deteriorated flex lines that are causing your issues.

 

I went with the premium fuel pump from O'Reilly's Auto

Lifetime warranty, and works good

 

I went with the Bosch from RockAuto. That is what was used from the factory. Also comes with a lifetime warranty.

I don’t put much stock in warranties though. Large print giveth, and the fine print taketh away.

 

Alright, I had enough time to cool off and take a breath since my test drive.

It was an eventful day. I won’t go so far as to say nothing was achieved, but the primary symptom persists. Fuel pressure dropping under load.


Filter arrived yesterday evening and was the first thing done this morning. That was an easy job.



Yesterday I put penetrating oil on the 3 fuel pump mount studs. Then I chased the threads with a die 8mx1.25 before trying to remove the nuts.



Fuel pump stud on the blind side.



Do yourself a favour and pull it as a unit.

I was looking at it and tried to disconnect the harness from the pump (8mm for the ground, 9mm for the power) and thought if it’s this hard to pull apart how will I ever get it back together while on the truck. She much easier on the bench.



This bucket of diesel was clean before running the immersed pump.

Once I got the pump out of the mounting bracket it went into a clean pail of Diesel. There must be a check valve in the pump since it wouldn’t pump steady with reverse polarity. So switched back and forth between forward and reverse. It did pump a lot of crap into the pail. That was encouraging.

Everything reassembled on the bottom side time to move up top and do the FPR.


Just to keep it interesting one of the bolts on the FPR stripped out.

Turns out I had to pull the fuel bowl after all. Made a couple calls to some friends, solicited my FB Superduty parts group and in the end bought a helicoil kit 5m x0.8 is that bolt size.

I had put the black spring in last time I had it apart which is rated for 70psi so I took that out and used the gold spring rated at 62. 55 psi is what it maxed out at and a quick drop to 40 under heavy right foot exertion.

Less than 2 blocks test drive and I was back home. Disappointed and frustrated and feel like I’m just throwing parts at it.

I thought hey, only thing left now is the fuel pump, or the Riff Raff FRx.

Then along comes noob and mentions the flex line.
Thanks Mang.

 

Hoping the new pump solves it for you!
I had the same symptoms and a new pump made no difference. Eventually I rebuilt the FPR with a new poppet, seat, etc and that was the solution.

 

I have one of those in my spare parts drawer, at home.
when the pump failed, I was in Utah at my sister's place,
went up there on a Family Emergency, packed my bags and left.

did not take the time, to grab my spare parts box

I had a choice, AutoZone across the street, or O'Reily's

 

You're welcome!!

Well, easy way to test the flex line (the entire frame rail fuel line really): 1. Check pump output volume on it's own. 2. Plug the pump into it's regular spot along the fule lines. 3. Disconnect the flex lines from the engine hardline. They're the same style of quick connect as at the fuel tank. 4. Run pump again and see if the output volume is the same.

 

https://www.ford-trucks.com/forums/1...hooting-2.html

Wondering if this is my problem.

Riff Raff FRx is also installed on my truck.

Doesn’t ring true though. Prior to Rusty Station fuel up I was running 58lbs steady with a drop to 52 on long steep uphill climbs.

But his symptoms were identical to mine.

Fuel pump is on its way.

 

Brand new Ford FPR went in it yesterday.

 

I would start with fuel pump since you got one on the way. Seen a guy yesterday on Facebook that posted some pics of his fuel pumo he took off his truck cut it apart and it was slap full of gunk and crud. Good chance that could be your issue.

 

Honestly the fuel pump is the last step.

I have removed and cleaned out the tank, removed a brand new 33972 wix filter, Installed the Baldwin BF1212 pre-pump filter with 30r9 fuel line from tank to pump, Threw out the brand new Napa gold fuel filter and replaced with ford fuel bowl filter, brand new ford FPR assembly.

Pump arrives today and tonight it will be installed. If that doesn't fix my issue then the Riff Raff FRx will be removed. If not fixed after that then remaining fuel line will be replaced.