Fuel pressure woes

[Digital Oxygen]

I've done a search for the problem, but I don't think I've found anything.


My 03 (6 liter for those of you who don't realize this is in the 6Liter thread ), started pushing over 150psi worth of fuel pressure. My Gauge only goes to 150SPI and it's over ranging it. Typically, it sits at about 65-70 psi. This happened over the course of about 4 hours. I noticed it when it spiked to 93PSI and about an hour later, it was overranging the gauge sender.

Now, if I get on it, the pressure drops to about 80psi when the motor is under load.

Pulled out the top fuel filter and replaced it (though the old one seemed fairly clean). No luck.

now, I found this thread about high fuel pressure. Are the 7.3 Fuel bowls the same as the 6.0? Do the 6.0's have the little screen in them?

http://www.superdutydiesel.com/forums/showthread.php?t=8845&highlight=fuel+pressure

Thanks for your input.

 

[DaveBen]

No the fuel filters are completely different. No screen in them either. There are TWO fuel filters, one under the truck below the driver's seat on the frame and the other on top of the motor (which you have found). Look in your OWNERS MANUAL!!!!!!

Dave

 

[Digital Oxygen]

No Need to shout, Dave. I asked because I've never seen a 7.3 Fuel bowl setup. I wasn't asking about the fuel filters themselves, but rather about that little screen the poster in the linked thread was mentioning. The steel wire mesh one in the FPR.

As far as the Main fuel filter, I know where it's at. I BETTER know where it's at, since I replace that one and the one on the top about once a month.
About the same time I also drain the water our of the HFCM via the fancy knurl knob I bought from International.

But thanks for trying... though, I fear you may have misunderstood my original question. No worries, it happens.

 

[bushpilot]

why are you changing filters once a month ?
are you using OE filters ? (there ARE some issues
w/ some 3rd party (read napa/wix) filters).

 

[Digital Oxygen]

Well sir...

I do idle the truck on average of 288 hours a month. High Idle. No major fuel in the oil after each 100 hours of run on the oil. But thats another story.

I am using Ford Motorcraft OEM filters. I pick them up for about 50 Bucks from a guy at five Star Ford in Scottsdale. I know, I know. Internationals' filters are cheaper.

so anyways... any ideas as to why I'm showing so much pressure?

 

[bushpilot]

i dont have any idea...sorry if ive missed it previously...
but why on earth did you decide to even monitor the fuel pressure ?

were you having other problems (or symptoms) ? are you running any
kinda tuner ?

 

[Digital Oxygen]

I like to keep an eye on the vitals. Fuel, Oil, Temps, etc.

Call me old fashioned.

No symptoms, no problems, no tuner.

But I think I may have found the problem. I think the Sending unit is bad. I swapped it with the oil sending unit, and that one registers about 65 at idle. Yes, they are the same type of sending units, same manufacturer, same PSI range. They are swappable.

With the sending units swapped, the oil gauge is now over ranging.

 

[bushpilot]

ahh good for you....

Im old skool too...guages are a good aide in finding problems
before they get outta hand.

 

[DaveBen]

But thanks for trying... though, I fear you may have misunderstood my original question. No worries, it happens.

I guess I did.

Dave

 

[Digital Oxygen]

I think I spoke (well,t yped) too soon. I've got no power, and the turbo is farting when i let off the go go pedal real quick. Truck's going in tomorrow, with 1500 miles left on the motor warranty. phew.