My friends 01 powerstroke with 160k is reading 37 psi at idle. Didnt do a road test, but I would guess it would just dop further under throttle. I know 60-70 psi is a good number to shoot for, but what problems would 37 psi cause, if any? Could it hurt fuel mileage or cause a rough idle? Should we shim the FPR or replace the fuel pump? Or should we just ignore it and let it be? It runs good right now, but it feels like it could run a little bit better.

 

That is inadequate for your friend's truck. I am surprised it runs even OK. Make sure the filter is good. May want to blow out the line from the pump back into the tank with compressed air. (open fuel fill cap for this) Better yet is to drop the tank and inspect the pickup and screens. Do the in tank mod if you go there. There are also restrictors in the heads where the lines go into the head but I doubt this is the problem. Where did you measure the fuel pressure?

His pump may be on it's way out. How many miles on it? Never mind, saw 160K. It may be time.

 

37 #s is real close to the low threshold. I would investigate the fuel pump, and all the fittings from the tank to the fuelbowl. It may be sucking air from the quick disconnect fitting at the tank and not letting the pump build the required pressure.
If the pump is deemed bad then a good replacement pump is the Walbro GSL392, its about $130 and will mount in the stock bracket.

 

He dropped the tank and clean the screens in the pickup pump after running biodiesel with enough glycerin in it to plug up the filter in a couple minutes. I'm not sure where they checked the pressure at ill ask em tomorrow. Ill have them check the quick disconnect and all the fittings. Any way to check the fuel pump and see if its shot?

 

Can i try shimming the fuel pressure regulator with a BB? Or should we go ahead and check for leaks, and if none are found replace the pump?

 

A mechanic at international told me to stretch out the spring a little in the FPR. Make sure you have the proper O rings if you open it up. I have been meaning to rig up a gauge for a while to check mine.

 

So pull out the spring and stretch it? I know on the OBS your supposed to put a small BB in there to compress it, so is it different in the super dutys?
Also, where should i get the right o-rings? Assuming they arent re-usable, would autozone or somewhere like that have them or should i go to a stealership?

 

Yes you have to pull it out and stretch it a little. I've heard of the bb way but either would work.

 

I've got instructions on how to do the OBS FPR shimming. Will these work or is the Super Duty's different? I would assume its the same, but I thought it'd be worth the time to check and make sure

 

You would be able to tell pretty quick with a gauge hooked up. You might want to do a search on this site, I'm sure it has been discussed in length. Somebody else might chime in with a good procedure.

 

Alright thanks for all the help. I think we'll try shimming and check the pressure, and if it doesnt change much well replace the pump.

 

Shimming is nothing more than a stop gap measure. If the pump is weak then the shim will only tax it more. On the back of the fuel bowl right above the fuelbowl heater plug is a test port. The fitting is pictured below its a -20SAE to 1/8" NPT, it can be found at your local hydraulics store. grab a 100PSI glycerin filled pressure guage from the hydro shop too, and then get you a 1/8th" NPT grease gun hose hook up and test for pressure.

here are some pics. the ones of the mounted fuel pressure guages are just to show what you can do with them.

test port


fitting and hose



guage mounting options

 

This is why I will no longer burn Biodiesel until it is more uniformly tested and marketed. I was about halfway into a Bio-only tour of the country this summer with family and Fifth Wheel when all this happened to me in the middle of nowhere Wyoming. It cost me dearly; replacing the pump, #8 injector, and a thorough clean out of the tank and lines. All I can say is don't let this happen in the vicinity of Rock Springs, Wyoming and I will never burn Biodiesel in my truck again.

 

I know this has been asked but how is the fuel filter?

What is the wether like there? really cold will make it harder for the bio to flow. I run WVO and use a very large pump to get that thick stuff moving.

Leaks in the lines can hurt your pressure but not this much, you should be able to get it and keep it up near 60psi.