I FINALLY installed my fuel pressure gauge - man I have been lazy! At first start-up and idle, my reading "settled in" at 42 psig. After driving it today and putting it through a few WOT runs, the pressure only dropped to 40 psig - and that was only for just a few moments. It stayed around 41 to 42 ALMOST all the time. It occasionally (rarely) went to 43 and 44, but when it did, it was always immediately after releasing the accelerator pedal after a hard acceleration.

Needless to say I am glad to have the information but disappointed in the fact that the pressure was ALWAYS below 45 psig.

Conclusion - It seems that the pressure is fairly stable under all accleration modes, so I would have to say that the pump is probably in good shape and that it almost has to be the regulator that is weak.

BTW -
The pressure sensor is coming off of the test port at the base of the secondary fuel filter. I am using an ITP hose (w/ schraeder valve at the end) to relocate the sending unit near the air intake filter. I bled the air from the hose after installation.

Truck has apprx. 52k miles. I replace my fuel filters at 10k mile intervals with Racor or International filters. I have 2.5k miles on the current set of filters. I ALWAYS change the filters at the "severe service" interval. I have never had any performance issues. I always inspect the fuel (drain first amount into a glass jar to do a visual inspection) at each filter change. Never had any bad fuel - in THIS truck anyway. I do use Stanadyne Performance Formula AND I add about 0.65 gallons of biodiesel (2%) every tank.

 

What gauge are you using? The numbers sound ok and the fact that it never goes any lower is a good sign.

 

I am using a Nordskog sending unit and electronic gauge. I suppose it could be off of calibration a bit also.

I agree, the fact that it is relatively constant at various throttle conditions is good. A Tech informed me that he has changed VERY FEW HFCM's (pumps), but quite a few pressure regulators (weak spring).

Ford is very specific about the 45 psig minimum for injector reliability. I will be confirming the gauge calibration and then take it in for warranty work on the regulator (if the gauge checks out).

 

the pressure is low.replace the regulator on the fuel filter housing.there cheap.

 

Check the calibration first. There are times when the testing device itself can be off no matter how we like to feel about a new purchase and how they are supposed to work right off the bat.

I had an tire pressure compressor gauge be off since the day I had bought it, I know not as damaging as this could be, but just to show that not everything works right right off the bat. I have learned to compensate for that(sometimes I have a hard time getting rid of somethings), but it is still off. Not saying that yours is, but it's worth making sure first.

If it does check out to be correct or even negligibly off, then I would check out the regulator, since like you've said you manage to have pretty constant fuel flow during various stages of throttle.

 

I have consistantly 13psi higher at the return regulator AFTER the heads than I do at the test port......but it is two different gauges, the regulator being manual and the indash being electronic. Been that way since both were new. Maybe you can get a calibrated test gauge to see what it really is Mark and go from there.

 

If you have a tire pressure gauge that you don't mind converting to spot-duty fuel pressure checking, use it to check the fuel pressure at the schrader valve on the ITP hose.

I had to crank up the adjustment on my Commander after replacing my egauges sending unit with the nordskog unit, so I wouldn't be surprised if your calibration is off by 10+ psi.

PS- I still have something wacky going on with my fuel pressures. They stay above 50psi, but they sure bounce around a lot. Couple that with the fact that I had a miss until hot when I first fired up the truck after sitting for 3 weeks, and I think I have an injector going south. Need to get a scan tool on it and take a peek at the cylinder contributions.

 

Great idea w/ the tire pressure gauge! Tried it and still low though. It is now in for warranty repair - man I hate not having the truck to drive !!!! The main reason I took it in was because I wanted the low fuel pressure situation to get documented on the OASIS report.

I was thinking - My EGR valve was very dirty - I mean VERY dirty. Some folks have fairly clean EGR valves. I know that the condition of your EGR valve can be like taking your own bodies temperature ...... it can tell you when something isn't quite right. I am now wondering if low fuel pressure could have been a root cause for my original dirty EGR valve. If so, I wonder how many folks are driving around with low (or borderline) fuel pressure?

Just another reason to get a COMPLETE set of gauges!

EGT and EOT/ECT are next!

BYW w_huisman - I love the nordskog gauge (can retrieve the high AND low readings w/ a push of a button).

 

I switched my gauges around this afternoon just to see if it was really a difference in pressure or gauges. Verdict is still gauges. I have exactly as much at the return regulator as I do at the test port on both gauges, although each gauge is 13psi different. I'm sure one of the screws on the manual gauge is an adjustment, but I'm not messing with it.

I actually have zero fuel pressure now as my FASS died on the way to pick up mama this afternoon. Truck is sitting a mile from the house in the parking lot of a tool supplier. This is the second in less than a year. Very disappointing. Fortunately I had already ordered an AirDogII that was supposed to ship today and may be in tomorrow or Friday. I already knew the FASS was going out this morning so I prepared. POS.

 

What a dissapointing and all-too-common occurrence! How can FASS stay in business at this rate??

 

This may sound silly, but did you check to make sure it wasn't an electrical problem?

 

This is not what I want to hear.My Fass is only 5000 miles old.

 

I think this is like what we hear about the 6.0 in the forums. We get mainly the bad reports. I thought I had a problem with my FASS and it was intermittent and it turned out to be the wire with the fuse tap was chaffed and shorting. Since I wired it myself I couldn't have expected more out of it as I'm sure it was something that I did. Mine is a lot older then 5k as well.

 

LOL--three fuses in a mile and the last two in less than a block. I have 8 ga. wire run from the battery to the factory motor connections. 40 amp relay triggered by the factory fuel pump wires. Pretty straight forward wiring. My dealer has gone through 5 on his truck, not to mention numerous internal upgrades that FASS has sent him. They say they only have this problem on RR Ford trucks. I just hope they stand behind it again. Like I say.......AirDog2 is on the way. I just can't trust the FASS anymore.

 

Bismic,

I am having the exact same thing right now. Or like you say possibly just figuring it out now that I have a way to check and a need to know.
Upon the recomendation from my tech I changed out the fuel pump yesterday and did see an improvement! I now have 55 to 56psi on idle. however at WOT it still drops to 45 to 48psi. This still has him concerned. He said there are two things he sees that can cuese this.
1) There are several screens before the pump. I think he said in the tank.
2) regulator.

He is going to bring home a regulator tonight and give that a try as it is an easy swap. Next he said we could take off the supply hose and run it into a diesel can and see what the pressure does. If it comes up then looks like screens.

Just thought I would post about the screens as no one has brought that up.

Hope you get "her" back in tip top shape!