Ford Powerstroke Diesel Forum banner

Losing rail pressure

7K views 16 replies 5 participants last post by  Caccamo 
#1 ·
Ok guys, I have a weird one for you. I'm working on a 2008 F-350. Engine was rebuilt earlier this year because of a cam issue. Truck was running fine after he got it back and about 3 months later it started setting a P0087 code for low rail pressure. I told him I'd check it out thinking maybe a bad FRP sensor. Sensor was working fine so when I started diagnosing it, I found metal in the fuel. So, I pulled the cab and replaced the pump. Also pulled the injectors and sent them to be checked. 4 out of 8 failed. The guy bought 8 new Alliant injectors, OEM pump and reseal kit and new filters. I pulled the fuel rails, cleaned them and flushed the tank and lines. Installed all new parts and filters, put everything back together and fired it up. Here is the issue. After getting it back together and getting ready to drive it, when you get to around 1250 RPM under a load, the rail pressure drops and kills the truck. Did as much testing as I could do and even replaced the FRP sensor again thinking possibly a bad one from Ford. Still does the same thing. Now I'm thinking that I have a bad pump right out of the box. Ended up getting pump warrantied and did the entire job again only to have the same issue. When you get the RPM in the 1250-1450 range and watch the rail pressure, the pressure is arlund 8600-8700 psi desired. As soon as it sees that range, the actual rail pressure drops down to the 2000 range and kills the truck. Another thing is that it will bot do it until ECT reaches 150°. Truck runs perfect until that temp. If you smack the throttle and get it past the 8700 psi range and get it into the 9000 range, the actual and desired pressures come back together and the truck runs fine. Anyone have any ideas because I'm about ready to burn this thing to the ground.
 
See less See more
#2 ·
Have you checked the hfcm? Almost sounds to me like the hpfp isn't getting the fuel......
 
#4 ·
@kaya @toren302

Truck deleted? I am guessing if it is you have tried different tuning? Is the pigtail going to the frp sensor in good shape?
 
#5 ·
Truck is fully deleted. Has a tune in it already and didn't have an issue before the new pump. However, it's a Livewire TS and the screen is unresponsive. I want to tune it back to stock and tben retune it and see what happens. Just waiting on SCT to get back with me to figure out what I need to do. FRP harness looks good.
 
#6 ·
I would check connections and wires for chaffing.
 
#7 ·
Did you clear and reset the hpfp tables? Need IDS for that tho. Not sure if other tools can do it.
My buddy had a truck couple weeks ago. Found some metal. They Swapped the pump. Started throwing a p0087. Same thing as yours. After warmup. Warrantied the pump. Same thing. Wasn't throwing the code before the repairs.
Reset the tables and boom. No problems since. You're actually supposed to reset them whenever the pump is replaced. try doing that. Reset all the fuel tables
 
  • Like
Reactions: CrazyS0b
#9 ·
Yea not gonna lie, I think I've only remembered to do it a handful of times myself. Never had any issues. But after hearing the grief my buddy had, I'll be remembering to every time.
I'm sure that's why it's in the procedure. Be that one time that'll bite ya
 
  • Like
Reactions: CrazyS0b
#13 ·
Lovely. So is it still doing the same thing as before? Or is it driving smooth in that pressure range?
 
#15 ·
Hmmm. Maybe try resetting them again. and let it idle, untouched, for a good 15 minutes or so afterward.
Worth a shot

You reset min/mass adaptation, yes?
Is there a ckp reset on the 6.4? Been awhile. If there is, try that as well
 
#16 ·
Finally got the running issue taken care of. I returned the truck to stock and then reset the fuel tables then reprogammed the truck. All was good until after I drove truck for a good hour. The truck still runs perfect but after you shut it off, you better hope you have a couple hours to kill because it won't restart. Acts just like a 6.0 no start hot. Got to checking and rail pressure would barely reach 1500 psi while cranking. Spent 2 weeks on and off checking everything and I determined that I was dealing with an excessive fuel return issue. Ordered the fitting to check fuel return but then decided that was going to be useless considering to do the test, the truck had to be at operating temperature and once it's warm, it won't restart. Finally contacted the company where I purchased the injectors from to see if there was a way they could test the injectors for excess return and simulate hot conditions. The guy called Tech Services to discuss my issue and called me back 15 minutes later. Said there was no need to test the injectors since there was a RECALL issued on 12-12-16 for the exact concern I was dealing with. So after all of the headaches I've had with this truck, I had to remove and replace all 8 injectors again. Now I'm just waiting for the tuner to get back again from SCT because when I tried to update it, it locked up. Will be a couple weeks before I get it back and to see if this truck is finally fixed so I can get it out of my hair, at least what's left of it!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top