[2002F250]

I just got done shimming my FPR, I used the kit from Diesel Innovations. I started with there .065" shim and got a reading of 60 psi (my stock pressure reading was 55psi), so I then put in the .075" shim (the largest in the pack) and still get a max reading of 60 psi. According to DI's instructions, the largest shim should put me at 70 psi or higher...what could be causing my low fuel pressure? I am taking my fuel pressure reading from the test port on the back of the fuel filter bowl. These are also idle pressure's, I don't have an in-cab gauge to see what happens under load. Could my fuel pump be weak? Could the pick-up screen in the tank be partially plugged? In the warmer months I do run B20 biodiesel, so that may have loosened/cleaned some junk from inside my tank and could be causing some plugging issues with the pick-up. Or could something else be restricting flow? My fuel filter was replaced only about 1,000 miles ago.

Oh yeah, lately the truck has been lacking in top end power when in the higher rpms's...lack of fuel supply? I've owned this truck for a year now and I know it had "umph" on top end when I first bought it.

Any ideas guys? /ubbthreads/images/graemlins/confused.gif

 

[kainers]

Weak fuel pump.

I don't know why you would want that high fuel psi anyway.Just wears the pump out faster.

I use to run at 72psi but now 55psi is plenty.

 

[2002F250]

Anyone? /ubbthreads/images/graemlins/frown.gif

On a side note I noticed when the truck is cold, such as from sitting overnight, it will idle at 65 psi and then slowly drop as the truck comes up to operating temp.... /ubbthreads/images/graemlins/confused.gif

 

[Oneof6]

[ QUOTE ]
Weak fuel pump.

I don't know why you would want that high fuel psi anyway.Just wears the pump out faster.

I use to run at 72psi but now 55psi is plenty.

[/ QUOTE ]

I agree, I can tell no difference if I set my regulator at 68 PSI or 55 so I run 55-58 PSI. Easier on the fuel pump, easier on the regulated return system hoses, probably easier on the injector o-rings.

 

[NYDieselDan]

I couldn't get my stock FPR spring over 60psi either. I could shim it until it coil bound and it would then spike the needle. I needed to change the spring to see 60+.

 

[2002F250]

Did you just replace it with the OEM spring? That was another thought I had, that the spring was weak.


Is it normal for the fuel pressure to be higher when the motor is cold, as opposed to it being lower when the motor is up to operating temp?

 

[NYDieselDan]

No, I happened to have a different spring that worked just right. But a new factory one would probably work better too.

 

[2002F250]

UPDATE:

I still cannot get the desired fuel pressure I'm looking for (~68 psi.) I have recently did the hutch and harpoon mod and there was nothing blocking or plugging my pickup screen in the tank. And there is all new fuel line (with a filter) between the tank and the pump. If anything, I think I lost a few psi since the install of the pre-pump mods, probably due to the restriction from the new filter? I haven't tried replacing the spring in the regulator yet.

Can anyone tell me how/what to check to see if the fuel pump is weak?

THANKS! /ubbthreads/images/graemlins/cool.gif

 

[Kanman]

[ QUOTE ]
Can anyone tell me how/what to check to see if the fuel pump is weak?


[/ QUOTE ]

Check the fuel pressure? /ubbthreads/images/graemlins/shrug.gif

 

[2002F250]

I've done that.....I thought maybe someone might know how a certain flow rate to check for? Or maybe a certain voltage level to check for?

 

[haul_n_horses2]

[ QUOTE ]
Can anyone tell me how/what to check to see if the fuel pump is weak?

[/ QUOTE ]Tested this along time ago. The flow rate on the fuel pump is normally about 1 gallon per minute at 0 psi and approximately 0.5 gallons per minute at 70 psi. To measure the flow rate at 60 psi, disconnect the return line at the fuel filter housing and put some hose over fitting and measure the flow rate. You will have to supply a continuous 12V DC from the batteries to the fuel pump. To do this I have a power port adapter with alligator clips which I can connect to the fuel pump and provide continuous juice to the pump.

 

[2002F250]

ANOTHER UPDATE:

I finally got an in-cab fuel pressure gauge, and it's reading about 68-70psi at idle. I made no change from earlier posts...I wonder if the way I plumbed the mechanical gauge caused an incorrect reading with the couple of 90 degree fittings I used? Anyway, it's actually running at the psi I was looking for....I just didn't know it. /ubbthreads/images/graemlins/smirk.gif As far as the pressure drop under load, it drops to about 62-64psi at WOT (not pulling anything)...maybe 60psi every now and then. Is this acceptable? /ubbthreads/images/graemlins/shrug.gif

 

[FionaThe02PSD]

IMHO.. 60 is fine. I'm only running 60-64 WOT with STG3 injectors and a complete fuel system..

What is it at idle?

 

[2002F250]

[ QUOTE ]
...it's reading about 68-70psi at idle...

[/ QUOTE ]

 

[FionaThe02PSD]

That's more than enough IMHO. Why do you want more PSI?

 

[2002F250]

I don't necessarily want more psi, I was just curious as to how much pressure drop under load is acceptable.

Thanks for the input. /ubbthreads/images/graemlins/wink.gif