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93-4.0 fuel pressure issues +- four psi…. I’m a dork

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Fuel pressure…. The book…. KOEO 35-45. KOER 30-40.

original fuel pump 136k miles, 3psi KOEO 26-28 KOER

Suspect fuel pump or pressure regulator weakening…

new fuel pump by Precision installed- KOEO initial burst 36, rests at 32 psi koeo. KOER 26 idling, 36 with pressure reg unplugged from vacuum.

new fuel pressure regulator KOER 28.5-29 psi, 38 psi with vacuum unplugged.

those small differences make a big difference in driveability. Damn truck!

4 psi makes a difference. Putting the bed back on and taking a test drive here in a couple minutes.
 


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No the truck is doing the exact same thing even with four more running psi….

so I was recommended by a fellow here to tear it down and flow test all the injectors.

the drive issue is stumbling randomly on acceleration, the stumbling STILL feels electrical to me. But everything dealing with the spark is new except the ECM, I replaced the bad capacitors in the ecm. Truck runs the same, no check engine light, testing codes gives 1-1-1 no trouble codes.

new plugs- no change
New Crank position sensor-
New TPS- no change
New wires 300 miles ago- no change
New coolant sensor for ecm- no change
New fuel pump and pressure regulator- no change
Tested and cleaned MAF sensor (exactly on parameters)- no change
All electrical connections clean and good.

everyone said the edis6 system is bulletproof, but can it cut power to coil pack signal randomly on acceleration?
It runs so damn smooth without moving down the road. And a feather light throttle driving you will not feel the stumbles, which points me personally back to the TPS…. So I’m going to warranty out THAT new piece.

one thing bugging me is this truck going through OEM pump won’t hit 40 psi, TWO in a row precision fuel pumps will NOT exceed 40 initial psi regardless of how Many keyed cycles. The pump is rated for 42 psi according to the parts store. Should I keep doing it until I find one over 40?

morning are there simple things I’ve missed that one of you can point out to me like a slap on the back of my head?
 

RonD

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Fuel filter was changed I assume?

EDIT: posted before reading last post

That 4psi shouldn't have matter that much, but if there were Driving issues, i.e. stumbling at higher demand then yes fuel pump was weak so pressure was dropping below 15-20psi during higher demand

FPR's internal spring is set for 43psi, so cycling the key on and off should get pressure up above 40psi
Or pulling off vacuum hose should see 43psi
Electric fuel pumps are capable of 80+psi, just FYI
So I am thinking your pressure gauge might be about 4-5psi low
Test it on your tire to see

The computer can adapt to lower fuel pressure, just sets Lean codes if its too low for long enough
30-40psi is spec but engine should run fine down to 25psi, 20psi should be the start of Lean Codes
 
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There are no codes it is idling at 29 psi and when I go to throttle it jumps up to 38 psi when the vacuum allows the fuel pressure regulator to close off….

28 psi at 2500 RPMs and 3000 RPMs and 29 psi while idling
 
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Two new fuel filters within the week two new fuel pumps within the last day and they’re all within one to two PSI of the 238,000 miles original Ford fuel pump
 

RonD

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Yes, EDIS-6 are bulletproof

O2 sensors?
Need new ones at 100k miles or 12 years

TPS is a good guess, its the equivalent of the Accelerator pump on a Carb
MAF sensor is too slow to react when accelerating, so TPS gives the computer a "heads up" to add more fuel and change spark timing for instant acceleration
Be sure to reset computer or unhook the battery for 5min when changing any sensor so computer will re-learn it, test it
 

2011Supercab

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@RonD
FEandGoingBroke has spent hundreds of dollars and many hours replacing every sensor, spark plugs, wires, coil pack on this truck, multiple times now the fuel pump and won't do a compression test, or flow test his injectors.
 
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“This guy” is Gary, I’m going to do your precious compression test right now and then you can use your genius mind to tell me exactly why the results make the truck run like it does.

flow test on the injectors will follow.
 
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I’m trying to be polite. So I’m going to do the compression test here in about an hour I’ve gotta let it cool down while I deal with another customers Chevy Silverado…
 

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Let's just take a deep breath gents...

@2011Supercab sometimes it's just better to not say anything at all.

@FEandGoingBroke sometimes it's good to start from the beginning and inspect the overall health of the engine by running a full blown compression test. At least you will know the heath of things before going further.

I just have a simple question... what spark plugs did you put in it?
 
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Here we go, sorry it took so long. Haft emergency transmission issue for a brother and a water pump emergency for my barista girls dads chebby. They’re all good. Now this dang ranger.

man this truck bugs me.


1- 142 psi
2- 140 psi
3- 120 psi
4- 130 psi
5- 120 psi
6- 145 psi

Well there it is 25 psi difference from the minimum to the maximum. And now that the warm engine compression test was done what are your thoughts? Why would the electrical be cutting out spark at odd intervals while accelerating? And how does this compression test satisfy any of the issue at hand relationally?
 
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The test was performed with the engine about halfway up to temperature after having driven it and letting it cool, Because nobody needs to burn the crap out of their hands and fingers pulling these plugs especially on the first bank where it’s crowded by the AC unit
 
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The plugs are autolite APP105 double platinum gapped to .053.
 
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Listening patiently for results of thoughts on compression test versus the issue this truck is experiencing.
I’m kinda insulted, but not in a fluffy democrat way, but in the way where I know that the overall compression has zero to do with an electrical issue or fuel pressure issue.
 

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