08 6.4 fuel pressure

[blownstang91]

Hey guys, new here just got an 08 6.4 not running put a high pressure injection pump in it and a harness and line kit and it was really hard to get to build fuel pressure when I got it all back together. I was cranking and it didn't show any fuel pressure on the scan tool so I let it sit for a min and cracked the driver side hi pressure line to the rocker box tightened it back up and started cranking again got it running and now when you first start the truck and go over 10% throttle the fuel pressure foes down to 500-2200 and surges up and down for a but 30 seconds then will stabilize and truck will run great. I was wondering if anyone had any direction for me on what might be causing my issue. Only happens when you first start the truck after that it runs great. New fuel filters good frame rail pump. Only thing done to the truck is an h&s and dpf delete. Does it stock thru performance settings. Like I said only on initial start up. Thanks in advance.

 

[duddy]

I have come to find a good workout cleans the air out of the rails fairly fast which would more than likely would be the cause. A decent weight trailer and some good hard pulls should clear it up.

 

[blownstang91]

I thought that might be the problem but I took it out and ran it hard for an hour or so shut it off started it right back up and it started all over again . I've been reading about rail pressure sensors and curious if anyone thought that might be the issue or if it might have a problem with the fuel pressure regulator on the pump?

 

[webb06]

You need to reset the HPFP adaptive tables after installing a new HPFP. You need IDS to do that. Not sure if that'll cure your troubles but its worth a shot.

 

[B585Ford]

You need to reset the HPFP adaptive tables after installing a new HPFP. You need IDS to do that. Not sure if that'll cure your troubles but its worth a shot.

:whs: after you reset them, let us know what the results are.

 

[blownstang91]

I reset them with my autel to no avail. No one I know that works on these things has any idea of why the issue only exist on initial startup.

 

[B585Ford]

I reset them with my autel to no avail. No one I know that works on these things has any idea of why the issue only exist on initial startup.

Any chance you are getting air into the system? Have you checked the Shrader Valve when you first start it up?

 

[blownstang91]

I don't believe so I check fuel pressure at the outlet of the frame pump and it's about 6 psi at idle only drops to about 4 under load.

 

[sootie]

seems a little low under load

 

[blownstang91]

It runs great aside from pressure surge at initial start up. I'm really at a loss. I wish it would run bad all the time feel like I could pinpoint the problem easier.

 

[blownstang91]

Watch "6.4 powerstroke fuel pressure surge" on YouTube
6.4 powerstroke fuel pressure surge: http://youtu.be/7stZlQWWGIw
Switched hi pressure fuel pump. Same problem. Rail pressure sensor same problem. 7 psi outlet of fuel pump on frame rail 6 psi on top of fuel cooler. When rail pressure bounces lpf maintains same pressure.

 

[AirFishAutomotive]

anyone have any other ideas?

 

[B585Ford]

I am having a similar issue. I had to pull the cab because of a bad surge and couldnt maintain RP. While i was in there we put in a LP system (Marty's). Now have to crank the LP up to 20 just to get it to run. Tried 3 HPFPs and a 2 A1000s and it doesn't change anything. Replaced the RP sensor and wires to HPFP. Checked output from the PCM to valves on the HPFP and that is fine. Activated the LPFP with the cab off and pulled the inlet on the HPFP and I am getting all kinds of fuel to the pump (FB is deleted). Pulled the return on the HPFP and getting almost no return (while the truck is running). Now I am in the process of replacing the line to the HPFP and trying a complete re-flash of the PCM. Already tried resetting the HPFP. I will let you know if this works. I am stumped on your problem and mine but they may be related.

 

[stroke6.0]

iv replaced many lpfp and never done a reset or had an issue. Does the truck have a fuel heater still? Iv seen an injector return too much fuel and actually dump pressure off. and once the engine warms up it will be fine. Cant really check that with the ids unfortunately. At first thought id say rail pressure sensor but you say its new. the low pressure seems a little low but wouldn't cause the surge.

 

[B585Ford]

iv replaced many lpfp and never done a reset or had an issue. Does the truck have a fuel heater still? Iv seen an injector return too much fuel and actually dump pressure off. and once the engine warms up it will be fine. Cant really check that with the ids unfortunately. At first thought id say rail pressure sensor but you say its new. the low pressure seems a little low but wouldn't cause the surge.

The reset is for the HPFP. You probably don't need to reset for just the LPFP replacement. If the LPFP was that bad as to starve the HPFP, it would be shot too.

My truck does still have the fuel cooler. I did forget to mention that I have already had the injectors flow tested also. I am not making oil either.

Blownstang91
Have you monitored your fuel temps? I would curious if the temps aren't reading funny when you have the problems.

 

[stroke6.0]

I meant hpfp sorry.

All 08s (job 1's) are a mega pain to get started. There is a fitting to install as a banjo bolt into the fuel cooler and it bleeds all the air from the system.

Id almost be looking at a bad hpfp even though its new. Or a hpfp cover plate gasket/harness. Seen them do a lot of weird things. Just this past week I replaced one causing the truck to randomly shut off. No ryhme or reason. And would start right back up. What happens if you do a self test KOER on demand with ids? Get any codes

 

[B585Ford]

I meant hpfp sorry.

All 08s (job 1's) are a mega pain to get started. There is a fitting to install as a banjo bolt into the fuel cooler and it bleeds all the air from the system.

Id almost be looking at a bad hpfp even though its new. Or a hpfp cover plate gasket/harness. Seen them do a lot of weird things. Just this past week I replaced one causing the truck to randomly shut off. No ryhme or reason. And would start right back up. What happens if you do a self test KOER on demand with ids? Get any codes

This question was for the OP right? I don't want to hijack a thread unless it will help the OP.

 

[stroke6.0]

Yes to the OP. Do you or original poster have ported rails by chance?

 

[AirFishAutomotive]

Truck is bone stock besides h&s w dpf delete. Hpfp would be plausible but it has done the exact same thing with two different hpfp

No on the ported rails only thing done is what was mentioned above. The injectors have not been flowed but it only does it on initial start up.....

 

[stroke6.0]

Every time or only first start of the day