Fuel pressure issues

blk350on20s · Sep 5, 2012

Well i went to the dunes to run around on the paddles and did my first WOT run with the new 60hp nozzles. Truck came out of the hole hard and then fell on its face. I glanced at the dd and saw low RP. Popped RP up on a bigger gauge and noticed it would spike in the 20s and then drop and maintain at 14-15000. Im gonna start with a gauge or just replace the fass unit anyway since its 6 years old. My hpfp is an elite stage 1 with around 60-80000 on it. Got it used from haller 1.5 years ago so i cant think of the exact mileage. That was my next step if the lp pump doesnt cut it. What are your guyses thoughts? Anybody have a hpfp with low mileage on it? Thanks. Ryan

Motostroker · Sep 5, 2012

I'm venturing to say that you are on the right track. IMO start with fass pump since it's way cheaper and pray it fixes it. If you have a stage one it should support 60's RP but then again with that many miles she may or may not be wore out. I'm waiting for elites bag of parts before I put some 60's in

Sent from the drivers seat of a Fire breathing 6.4

madman1234509 · Sep 6, 2012

Id get a lift pump gauge on the thing and throw it in the cab for a bit to see what its doing. If it holds, then you know for sure its the hpfp. If it drops, then you know its the lpfp. With your age/mileage it could be a combination of both. Its hard to say and just throw money at one or the other without diagnosing...

Also you may be able to check amps being drawn on the lift pump. I believe on here or PSA there was complete brand new stock fueling a guy was trying to sell. Lift pump, filters, lines, injection pump, all from ford still in packagine for 1200 bucks. Even if you only want the lift pump you could keep it, sell the other stuff and make money back. I know a new lift pump from ford is 600. All lines are a few hundred, filters are a bit, and a hpfp new is 1000-1200

MorganY · Sep 6, 2012

Ive got coltons (Super08Duty) 40,000 mile lift pump that I am sure he'd let go for the right price if you need one

Dzchey21 · Sep 6, 2012

I think its the low pressure pump mine did the same exact thing. With your nozzles I can't imagine seeing much less than 20k if the pump is wore out and you shouldn't really feel it fall in its face

08BIGRIG · Sep 6, 2012

Last night we checked my buddies FASS pump because the same issues you are having and his pump was all over the place for pressure. Was jumping from 10 to 20 at idel to Wot. Check that first as it is really easy.

blk350on20s · Sep 6, 2012

Thanks guys. Been talking to colton a little bit as well. Im ordering a few pieces from summit. Gonna throw a gauge in the cab via the window mod lol and see what it does. My line from the fass to the pump is 1 piece so the gauge will be directly off the fass. Is that fine?
Dustin thats exactly what i was thinking. 15000 is very low for even a worn pump. Had to be runnin out of fuel.

Dzchey21 · Sep 6, 2012

Ideally you would check pressure closer to the injection pump but I think anywhere in the low pressure system.should be ok

Motostroker · Sep 6, 2012

What kind of psi should we see from lift pump? 13-15?

Sent from the drivers seat of a Fire breathing 6.4

blk350on20s · Sep 6, 2012

Factory pump is low. I think somewhere around 10. I have my fass set at 15 or so.

blk350on20s · Sep 7, 2012

Well i put a gauge on right at the fass. It reads 5 no matter what. Thats low to me but it still maintains 5psi the whole way through. What you guys thinkin? Both bad?

MorganY · Sep 7, 2012

Try getting the low side pressure right first before you throw a HPFP at it.

blk350on20s · Sep 7, 2012

I figure it needs both. The lp is only kickin out 5. Its supposed to be high teens. Ill prolly get a lp pump monday and see what happens

madman1234509 · Sep 7, 2012

Id say thats a good start. Obv if you have it set at 15ish and it puts out 5, somethings not right.... Then go from there.... Let us know how you make out monday!

mortal798 · Sep 7, 2012

Factory lpfp should be only 3-8psi. But since you have FASS, I don't know what that is supposed to be...

blk350on20s · Sep 8, 2012

I have my fass with a dodge common rail spring in it. It should be in the mid teens.

78f100 · Sep 9, 2012

Not sure how many miles you have on it since you put the nozzles on, but if you did nozzles and rails at the same time it could be a leak. I had a leak on a ported rail causing my rp to fall to 17-18k after my build. It took about 250 miles to notice the fuel in the oil. Since I fixed the leak I can hold 24.5 on the 345 as before. Since then I put xrace on it and can only maintain 21.5 with it, my hpfp is just too weak to support the 60's with higher pw.

If you were maintaining rp before installing rails and nozzles, and didn't change anything else. That seems like a huge pressure drop just from going up to a 15% bigger nozzle to me. (I am no expert)

Goodluck with sorting it out Ryan!

blk350on20s · Sep 17, 2012

Ok guys. Got my new fass pump on and its at 15-16 psi. Holds the whole time. My rail pressure is getting lower and lower it seems. 12,500 to 13,000. Its not even spiking when i first get into it. Easy driving in lower gears i cab get 24500 out of it but wot from a o/d roll wont make ****. I dont smell fuel in the oil. Thinkin of gettin the hpfp from sunrise in the am. What are your guyses thoughts?

MINK · Sep 17, 2012

Sucks buddy, deff sound like your hpfp has taken a dump - makes me want to re think nozzles. Have you tried any small tunes just to see how it responds?

blk350on20s · Sep 17, 2012

Not yet. It has the idp extreme x in it now. I had the gear head race with low pw and it still was **** on rp. I really wish i beat on it before nozzles. Well atleast beat it while in a good state of mind lol. Im pretty sure it was droppin rp before as well