can high fuel psi(100) = less mpg?
first let me thank David (Bulla) for the help. i put a fuel psi gauge on the fuel bowl and it was over 100psi. at idle it was around 110psi and on the road it was 95-101psi at WOT. i called David and he helped me fix the problem, i think it was a clogged return line. has this happened to anyone before? now it is 62psi where it should be.
with all that said i have had my FRX on for +4 weeks and have had low mpg for about a year. so i dont think that made the high psi, and i looked in the end to see if it was right.
the fuel bowl has never been able to fill full from a filter change with out some troubles, all was had to tighten it good or it would leak. i think the line has been clogged a long time that is why i had the fuel leak. can high fuel psi cause lower mpg and what could have clogged it?

 

Where did you get the fuel pressure set up? I am also interested in doing this.

 

Yes, higher fuel pressure will cause lower fuel mileage.

 

Interesting. Whitey ran over 100psi fuel pressure also, I know for sure it wasn't a clogged return line but I never did figure the problem out before it got totaled. I always thought it should have gotten an mpg or two better than it did.

 

i got the fitting for Oring.com then just a gauge and some hose.
on the first run to day the EGT's are 225 cooler than "normal" so i think this will help my mpg.
i dont know if it was a clogged line but that is the last thing i did to make it work.

 

Why would that make a difference?

 

What fitting did you get? I would like to make a fuel pressure gauge too.

 

Im not really smart enough to explain it, but the situation has happened to members here before and lower fuel mileage was one of the symptoms of excessive fuel pressure. Maybe someone more knowledgeable will come along and can actually explain why. I would imagine it is simply because the injectors are less efficient at the increased pressure.

 

I would imagine it has to do with proper fuel atomization.

 

this is what i used then 1/8 to hose then gauge.
Replacement O-rings for Ford Diesel Engines

 

dont quote me, but i think a grease gun bendable hose will fit...has the samethreads plusthe hose is rated for 4k psi. Not bad idea too, to make a hpop quik gauge.

 

From my experience these are symptoms associated with a sticking FPR. If you have your fuel pressure gauge connected permanently then you might want to keep an eye on it to see if it spikes over 100 psi again. Hopefully you solved your problem, if not then you might be looking at an FPR rebuild kit.
Replacement O-rings for Ford Diesel Engines

 

that is what i though it might be but the FPR plunger is not tight in the housing. i think it was a plugged line. with out the FPR in i could get 9-7 psi on the bowl.

 

After reading what you just posted I'm not so sure it was a plugged line. If the plug was clogging and building 100 psi it would do that regardless if the plunger was installed or not. Like Greg said keep an eye on it and hopefully your milage will improve! And thanks Matt, anytime!

 

that may have been the case but it is holding 62 all the time.