Fuel pressure (again)

[Trqmnstr]

114,000, Stock pump, blue spring, glow shyt fp gauge.

Let the pile warm up fully this morning and pulled a WOT un boosted, fuel pressure went below 20 real fast so i lifted and it came back up to almost its normal of 60 PSI. It Took about 5 mins if driving 50 mph to get it back up as it hung around 58 for a bit.

My batteries died a few days ago and i tried to jump it a few times to no avail. Is it possible somehow the fuel system sucked some air while i was cranking trying to get it started?

Another note.
Had a noticeable power loss on the WOT where the pressure dropped. Not bad but noticeable.
I did notice the fuel pressure was a bit lower than normal at idle till warm up. It usually sits at 62 idleing and today was 58.

After 10 minutes of driving it was back to normal (drops from 60 to 58) while pulling some roll on WOT from 35 mph and was at its normal 62 while idleing.

 

[Mdub707]

I doubt it sucked air. What mods are done to the truck?

 

[Trqmnstr]

Fawk, just noticed my sig is gone.

Delete, studs, machined heads for flatness, new oil cooler, coolant filter, mbrp turbo back 4", cai, blue spring, GS fp gauge with strictly sender relocation (below bowl and mounted on hard parts in front of air cleaner.

I had forgotten but also the FP has been reading almost 70 on real cold days at idle until the motor is at operating temp for 10 minutes. Cold being below zero and the coolant doesnt reach its normal temp on the gauge on real cold days even after driving. Not that i think the coolant has to do with anything but I think the sender is off untill it gets warm in the engine bay.
It was almost 30 today tho when this FP business happened so the sender was plenty warm.

 

[Mdub707]

I don't think the small fluctuation of pressure change when the outside temp is dipping way down is anything to really worry about. The dropping to 20psi under WOT is definitely something to worry about. When's the last time the fuel filters were changed?

 

[Trqmnstr]

Lil over 6k ago when i bought the truck. Old secondary was nasty but the frame mount was reasonably clean. Changed oil three time since then last change with T6 and hot shots. I had stiction issues before the T6 and have had this FP drop ince also but the sender was taking a dump at the same time.

 

[Spoolin']

Having the same problem. Same modifications, Isspro fuel pressure gauge, just changed fuel filters, and still having problems. 200K miles. Stock pump. Psi is around 55-57 at idle and drops to 50 on normal acceleration. At WOT, it drops to 15-10psi. I am considering getting a sump and 6.4 pump to feed the stocker to see if that solves the problem.

 

[Trqmnstr]

I am thinking the same thing
New OE pump with a 6.4 feeder and a sump.
Probly can get away with just a new OE pump but im not even tuned yet so may as well have the extra assurance of a feeder for when more fuel is getting thrown around.
Air dogs scare me and im reading of more and more Fass failures lately.

 

[Trqmnstr]

Stumped

20 degrees this morning and pressure didnt drop below 58 from dead WOT launch
Only difference is i the ECT wasn't fully hot this time.

Research says the fuel pumps dont slowly go out, its an all or nothin thing. If thats true or not IDK.

 

[Mdub707]

Yeah that's interesting that it's intermittent. May just be time for a new pump.

 

[Trqmnstr]

Yeah, im gonna try a new pump. Also gonna go ahead and assume the airtex ones are junk and just go with a OEM from a dealer.
Then when it gets spring time ill throw on a sump and 6.4 pump as a lift before i even bother with tuneing.
Fawk these motors require a lot of loot before the fun parts. Lol

I cant find any info on These pumps besides "it just shyt and left me stranded"
Gotta be due to people not changing filters regularly i guess, fuel getting backed up into the pump from clogged filter and it just blows the pump. Idfnk

 

[Trqmnstr]

Anyone know if this is an actual OEM pump?
Does anyone make a better OEM style pump.

Basically im looking for the best option besides a Fass or AD system.
http://www.1aauto.com/1A/fuel-pump/..._content=FPU&gclid=CMnTnd_qprsCFUgS7AodUTQAIg

Had the same issue yesterday on a 35 mph roll on, pressure dropped to 25 so im thinking i need to swap this pump out pronto.

 

[Trqmnstr]

Nvr mind
Ordered the pump from Tousley,$275
Still cant beat the prices even with their new name. Customer service rocks also. I fugged up my card security code online so i gave them a call, took all of 30 seconds to fix it!

New filter from diesel filters online, second time to change those bishes in less than 10k miles. Lol
They where out of stock on Racor's tho so i had to drop the extra 10 bones on fomoco filters.

To add to the confusion today i pulled a first gear WOT roll on and it dropped to 30 psi and falling fast so i got out of the throttle. cruised a bit and then a 35 mph roll on and it stayed right at 60 psi. Both fully warm coolant

If its not the shyty GS sender or gauge it has to be the pump. We shall see i guess, with my luck the sender will take a crAp the day the new fuel pump shows up. Lofl

 

[Mdub707]

Yeah I find it hard to believe the pump is working fine one second and then not the next. Unless the spring in the regulator is sticking somehow and popping off early other times? It just doesn't add up.

 

[Trqmnstr]

Why did you hafta say the spring may be sticking. Its to fawking cold to pull the FP relocator hose and then reg spring. Lol
The "somehow" part got me thinking and iirc that spring has a lot of wiggle room on the houseing end and had pretty good tension when i put the houseing on. I dont see how it could hang up anywhere but almost anything is possible.
If the pump doesnt fix that ill check the spring, actually im gonna tap on the housing a little bit and see if that does anything.

 

[Trqmnstr]

Well
Tousley ford still rocks
I ordered just the pump and they sent the whole housing and all for $275

 

[Trqmnstr]

New OE pump installed, 63 psi at idle and never drops belo6C34-19E624-AA.w 60 no matter what you do. Also ive noticed that with the old pump when the power cut off to it the pressure would immediately drop to 0. With the new pump it drops slowly taking about 10 seconds to get to 0 psi.
So i guess there are warning signs to a failing fuel pump, it isnt just an immediate complete failure situation. At least not with this one anyways.

Cliff notes
OE pump with 114,000 miles started dropping pressure on WOT and showing slightly elevated pressure at idle. As time went on the WOT pressure was dropping below 30 psi.
Cruising pressure was fine at 60-63.

New OE pump and all is better.