fuel psi

[97BambiBasherPSD]

i hooked up the fuel psi gauge in my truck and its only reading 35psi running. if i let the glow plugs warm up it will creep up to 50psi then when you start it it drops to 35psi. i have the blue spring in it too. if i am correct thats too low. the filters were just changed 2000 miles ago. it never drops psi at all. just sits at 35psi. should i try filters again? pump goin bad? if so whats my options? would the low psi be a cause for an intermittent hard cold start?

 

[MrOneEyedBoh]

I would say the pump is going bad. Should be 60-70 ( obviously give or take ) with the blue spring. Minimum is 45

 

[Trqmnstr]

What brand gauge set up and is the sender right on the fuel bowl or relocated with a hose?
If it is relocated you may need to purge the air from the hose.

When my pump was taking a dump it would hold 60 psi at idle and cruising but WOT it would drop to 30-35 area. New pump and it holds 65 idle and 62 WOT.

If it builds pressure with the pump on and looses it at startup it seems like the pump isnt keeping up with fuel demand. Id get a new pump pronto, 35 is like injector suicide.

 

[97BambiBasherPSD]

It's an isspro ev2 gauge and it's right on the fuel filter housing. Yeah I had a sinking feeling about that. Dammit. What does one cost?


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[MrOneEyedBoh]

The pump? I bought mine from Amazon for super cheap. PFB-101 for 243 shipped. Even comes with fuel filter and cap

 

[97BambiBasherPSD]

I'll see what ford wants for one since I still get the discount from working there lol


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[MrOneEyedBoh]

Lol yeah that number I gave is the most current

 

[97BambiBasherPSD]

So would the failing pump be an issue for an intermittent cold start?


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[Trqmnstr]

Not positive but i would think if your fp is way low the truck probly wouldn't want to start good. If you wait till the pump shuts off before you crank the motor its always gonna crank a few more times than when the pump is pressured up before it fires, even with a good pump. You said yours slowly builds pressure so if your waiting for the inductive heat cycle to stop on cold days your pump is off before you crank the starter.
Its pretty easy to hear when the pump shuts off, im guessing around 20 seconds after you turn the key on, obviously your fuel pressure gauge is gonna drop to zero when the pump shuts off.

So the motor is probly firing when the fuel pressure gets to a certain minimum psi and its taking the pump a while to get that pressure built up.

 

[97BambiBasherPSD]

Well I think filters need changed since I just got the water in fuel light on


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[GatorBaitR6]

No just drain out the little box side of the housing... and just for the record ur gauge sensor is connected to ur filter housing where it's really hot and shaky which electronics don't like... have u gotten a mechanical gauge hooked it up and checked it to make sure it's not a bad sending unit...? they so make relocater hoses to take your sending unit further away....

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[97BambiBasherPSD]

It's on the filter housing on the side of the oil filter housing. I changed the pump and it seems to run better but it's still only showing 35psi. Iv got some fuel filters coming. If that doesn't change I will try a mechanical gauge to see what that does


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[GatorBaitR6]

The drain I was talking about above is on the fuel pump on the frame...

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[97BambiBasherPSD]

I know the drain your talking about. What I posted is where my fuel psi gauge is hooked up at. Unless you mean to hook the psi gauge at the drain port. Which iv never heard of before


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[97BambiBasherPSD]

Weirdest thing is that my psi is coming slowly up.


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[GatorBaitR6]

No lol i wasnt saying hooking up to the drain line lol... I just didnt want you to try and find a drain on the fuel bowl lol... I really think it might be the sender... is the truck riding rough or anything performance wise..?

 

[wiseguy]

Napa sells same pump as ford different box NFP P76115M it includes new jumper harness

 

[97BambiBasherPSD]

No it runs amazing. If you punch it and it throws black out and cranks 30psi and just flat hauls ass


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[Trqmnstr]

Weirdest thing is that my psi is coming slowly up.


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Mine comes right up within a second with the glow shyt gauge. Your sender is mounted right to the fuel bowl so maybe there is air trapped in the sender, if it is the same style as a GS sender. I used the driven diesel relocation hose which has a purge valve to get the air out. There was a big air pocket in mine but idk what the pressure was at the time, i purged it right away.

Getting those filters changed out is a must anyways but i think your truck would run like a$$ if it rly was only making 35psi.

 

[97BambiBasherPSD]

That was my thought too honestly. Ever since my psi shows it was coming back up the pump has been a lot quieter too. What's the range for a blue spring mod psi wise?


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