Throw a new fuel filter at it, I had the same issue when I redid my fuel system. Actually did a quick little “delete” just to see if anything changed as I drove around the block. (Probably not smart so do at your own risk I suppose) Sure enough it ran perfect so I ordered a serviceable one right then so I can pull and clean it out wherever I am.


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My set up is very similar to the pic Eck posted up.
Tank---NEW cheapo filter---LP pump----accumulator----HP pump---NEW filter---injectors---Return to accumulator---tank

32 psi and was at 22 psi an hour or so later

What's a quick little delete?

Eck-What post HP filter do you use?

Bypass the filter for testing purposes is what I meant. If the filters are both new that shouldn’t be the issue then. What cheap filter are you using?


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Good enough GPM and clear so you can see contamination probably rules that out.

You said you were EFI, do you have an fuel pressure regulator on the rail?


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I'm still having problems with sputtering and occasional backfire when accelerating or putting load on the engine (going up a hill). I tried going without the hp filter but that didn't change anything.

Primed and after the engine is off the psi is 40
Idle psi is 34
Before I go after the injectors is there a way to test the pressure regulator?

Thanks!

https://axleaddict.com/auto-repair/How- ... -Regulator

A new FPR is about $50 at O’Reilly’s.


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FPR passed the tests. Thanks for the link.

Jog my memory, this is a stock tank with the factory pickup/sending unit right? You might consider pulling the pickup out and confirming the “sock” isn’t falling apart and plugging the pickup.

Quick Update:
I pulled the upper intake and got to the injectors. I soaked, cleaned, tested, and blew them all out. I ordered a rebuild kit and put it all back together. No change. Idles fine but sputters on acceleration or load.
I had a spare hp pump so I threw that in and it ran the same as with the other pump. I guess I could through a new FPR at it but I'm guessing it won't change anything.

Primed psi is 34ish
Idle psi is 34ish
With Engine off it holds at 40 psi for awhile.

Not a stock tank but an older 22 gal (thanks for chimng in Kirk)

Anything else guys can think of?

Thanks.

I replaced the FPR with a a new one and it didn't change anything. I'll post up on CB.com and get a few more opinions. Feel free to chime in if you have any thoughts.
Thanks guys!

Perplexing

did you check your timing?

I'm just stabbing at this, but could it be a dirty mass air sensor or bad TPS?

I don't remember, is this mustang or explorer EFI? If it's explorer you can't change the timing.

It "was" a mustang efi but we swapped it over to the explorer harness and coil pack a few years ago.

Oh, I changed my air filter and cleaned the MAF a couple months ago

As for the TPS---if it were faulty, would it sputter if I rev -ed it in park/neutral. Only asking because when I rev it in neutral it sounds / responds great.

Well the good thing about the explorer EFI is you can hookup a good scanner and look at all of the sensors while they are working. You can also see if it has any codes stored. I might know a guy with a scanner.

Is it close to " Larry the Cable Guy"?

I videoed the FP gauge driving around the hood: idles at 36 psi and during acceleration it'd go up to 40-41 psi. I figured the FPR knows what its doing but could there be too much gas and bogging the engine down?

Nice! Now can we move onto other things?