Low fuel pressure wot
04-26-2018, 08:58 PM
#11
Senior Member
Ok, had a somewhat similar issue on my 2011.it had nothing to do with the motor though. 60k on my 5.0 At just above 4000 rpm it would start cutting out. Couldn’t get rpms above. Went into dealer as I had extended warranty. Dealer found fuel pressure fell off as rpms increased. They replaced the fuel pump in the fuel tank. About 1200 bucks but this took care of the issue. If it’s not motor then look deeper. Truck ran fine up to higher rpms. Had I not been towing my travel trailer I might never have found out.
04-28-2018, 04:14 PM
#12
Junior Member
Thread Starter
Join Date: Jan 2018
Posts: 8
Likes: 0
Received 0 Likes
on
0 Posts
Ok, had a somewhat similar issue on my 2011.it had nothing to do with the motor though. 60k on my 5.0 At just above 4000 rpm it would start cutting out. Couldn’t get rpms above. Went into dealer as I had extended warranty. Dealer found fuel pressure fell off as rpms increased. They replaced the fuel pump in the fuel tank. About 1200 bucks but this took care of the issue. If it’s not motor then look deeper. Truck ran fine up to higher rpms. Had I not been towing my travel trailer I might never have found out.
05-04-2018, 12:20 PM
#13
This is a common problem with Direct Injection on Gen 1 Ecoboost engines. The problem is not your rear fuel pump but your HPFP. The HPFP is mechanically driven and below 2,500 rpm, due to the low rpm, there is a tendency to not provide high enough fuel pressure. This is why changing your rear fuel pump - which is electrically driven will do nothing. If you ONLY produced 800 psi ALL the time, then it may be the rear pump. But if it is only at lower rpms and hits 2000+psi at higher rpms, then the HPFP is the problem (and possibly the tune).
The Ecoboost engine can produce a ton of TQ at low rpms, but the HPFP may not be able to deliver enough fuel (because it is mechanically driven and too slow at low rpms). Tuners like to emphasis this low rpm TQ, but this can also be dangerous. You should watch the difference between your ACTUAL HPF pressure and DEMAND HPF pressure (and see the difference), but also you lambda for your AFR to make sure it is not getting too lean.
The solution is two fold: 1) Reduce the TQ produced at lower rpms in WOT. This will reduce your fuel requirement and avoid a overly lean condition. 2) Install a higher capacity HPFP.
PS: I have seen lower high pressure fuel demands while in WOT - (500psi) with the stock HPFP and the engines were fine - just needed to reduce the TQ demand.
The Ecoboost engine can produce a ton of TQ at low rpms, but the HPFP may not be able to deliver enough fuel (because it is mechanically driven and too slow at low rpms). Tuners like to emphasis this low rpm TQ, but this can also be dangerous. You should watch the difference between your ACTUAL HPF pressure and DEMAND HPF pressure (and see the difference), but also you lambda for your AFR to make sure it is not getting too lean.
The solution is two fold: 1) Reduce the TQ produced at lower rpms in WOT. This will reduce your fuel requirement and avoid a overly lean condition. 2) Install a higher capacity HPFP.
PS: I have seen lower high pressure fuel demands while in WOT - (500psi) with the stock HPFP and the engines were fine - just needed to reduce the TQ demand.
05-10-2018, 08:36 PM
#14
Junior Member
Thread Starter
Join Date: Jan 2018
Posts: 8
Likes: 0
Received 0 Likes
on
0 Posts
This is a common problem with Direct Injection on Gen 1 Ecoboost engines. The problem is not your rear fuel pump but your HPFP. The HPFP is mechanically driven and below 2,500 rpm, due to the low rpm, there is a tendency to not provide high enough fuel pressure. This is why changing your rear fuel pump - which is electrically driven will do nothing. If you ONLY produced 800 psi ALL the time, then it may be the rear pump. But if it is only at lower rpms and hits 2000+psi at higher rpms, then the HPFP is the problem (and possibly the tune).
The Ecoboost engine can produce a ton of TQ at low rpms, but the HPFP may not be able to deliver enough fuel (because it is mechanically driven and too slow at low rpms). Tuners like to emphasis this low rpm TQ, but this can also be dangerous. You should watch the difference between your ACTUAL HPF pressure and DEMAND HPF pressure (and see the difference), but also you lambda for your AFR to make sure it is not getting too lean.
The solution is two fold: 1) Reduce the TQ produced at lower rpms in WOT. This will reduce your fuel requirement and avoid a overly lean condition. 2) Install a higher capacity HPFP.
PS: I have seen lower high pressure fuel demands while in WOT - (500psi) with the stock HPFP and the engines were fine - just needed to reduce the TQ demand.
The Ecoboost engine can produce a ton of TQ at low rpms, but the HPFP may not be able to deliver enough fuel (because it is mechanically driven and too slow at low rpms). Tuners like to emphasis this low rpm TQ, but this can also be dangerous. You should watch the difference between your ACTUAL HPF pressure and DEMAND HPF pressure (and see the difference), but also you lambda for your AFR to make sure it is not getting too lean.
The solution is two fold: 1) Reduce the TQ produced at lower rpms in WOT. This will reduce your fuel requirement and avoid a overly lean condition. 2) Install a higher capacity HPFP.
PS: I have seen lower high pressure fuel demands while in WOT - (500psi) with the stock HPFP and the engines were fine - just needed to reduce the TQ demand.
07-25-2019, 06:51 PM
#15
Junior Member
Join Date: Jul 2019
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Hey guys and gals I have a 2013 3.5 eb with 114k on it..the truck has been tuned for the past 20k of its life and about 8k ago it has been breaking up badly at wot or high load situations.
I have sent logs to torrie at unleashed and he said the rear fuel pressure is dropping badly. It goes from 2200psi down to 800psi and then the truck starts to break up bad.(I know I should have a vented block by now)it’s not tune related and torrie has been a huge help so no bashing please.
things I’ve done...
new oem plugs gapped to 26thou
replaced all pressure sensors including fuel pressure sensor.
replaced hpfp
replaced in tank pump with a 455lph walbro
checked cam lobe and follower
I have sent logs to torrie at unleashed and he said the rear fuel pressure is dropping badly. It goes from 2200psi down to 800psi and then the truck starts to break up bad.(I know I should have a vented block by now)it’s not tune related and torrie has been a huge help so no bashing please.
things I’ve done...
new oem plugs gapped to 26thou
replaced all pressure sensors including fuel pressure sensor.
replaced hpfp
replaced in tank pump with a 455lph walbro
checked cam lobe and follower
Checked timing chain tensioner(out 4clicks)
drilled weep hole in intercooler.
ran direct 12 volts to lpfp
ABSULTELY NO CEL’s
im leaning toward throttle body or fuel injector but the truck runs perfect during normal commute.. please help me
drilled weep hole in intercooler.
ran direct 12 volts to lpfp
ABSULTELY NO CEL’s
im leaning toward throttle body or fuel injector but the truck runs perfect during normal commute.. please help me
07-27-2019, 10:21 AM
#17
Junior Member
Join Date: Jul 2019
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Was hoping you would say found the issue, easy fix, didn't cost anything, and everything is resolved. A man can dream...
