Fuel Pressure Decreases with Throttle... - Diesel Bombers



12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

Reply
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 03-03-2013, 07:49 AM
Sudia247's Avatar
Diesel Enthusiast
Thread Starter
 
Join Date: Jun 2010
Location: Sacramento, CA
Posts: 272
Default Fuel Pressure Decreases with Throttle...

So I finally got my fuel pressure gauge all hooked up. It's an Isspro Ev2, and I also have the Tork Tek OFV020 Adjustable Overflow Valve. At idle, the gauge reads 25 psi, which is what Tork Tek states it should be. But as I give the engine some fuel, the fuel pressure decreases, instead of increasing.. I have not brought it to WOT yet, but bringing it up to just over 2k rpm, with about 10 PSI boost, the fuel pressure is about 20 psi...

My truck is all factory besides an Air Intake, and 4" Straight Pipe..
Reply With Quote
  #2  
Old 03-03-2013, 08:01 AM
mysterync's Avatar
Diesel Bombers Sponsor
 
Join Date: Mar 2007
Location: Blowing Rock,NC
Posts: 3,791
Default

How old is the fuel filter? Could be a failing lift pump. A cracked fuel heater will cause a similar complaint with a hard start. The in tank module can also be restricted!

Sent from my DROID RAZR using Tapatalk 2
Reply With Quote
  #3  
Old 03-03-2013, 09:00 AM
sweetv8s10's Avatar
Diesel Enthusiast
 
Join Date: Nov 2009
Location: El Dorado Springs MO
Posts: 498
Default

When it is under a load it will drop. 20 psi sounds ok to me.
Reply With Quote
  #4  
Old 03-03-2013, 09:17 AM
mysterync's Avatar
Diesel Bombers Sponsor
 
Join Date: Mar 2007
Location: Blowing Rock,NC
Posts: 3,791
Default

Quote:
Originally Posted by sweetv8s10 View Post
When it is under a load it will drop. 20 psi sounds ok to me.
I guess i should have read closer. I saw 10 psi .

Sent from my DROID RAZR using Tapatalk 2
Reply With Quote
  #5  
Old 03-03-2013, 09:58 AM
Sudia247's Avatar
Diesel Enthusiast
Thread Starter
 
Join Date: Jun 2010
Location: Sacramento, CA
Posts: 272
Default

So it's normal to drop fuel pressure under load? But the fuel filter is new, about 2k miles on it. I removed the fuel heater as well.

I was thinking it could be a failing lift pump, but I wasn't sure, Ill give it WOT and see where it drops to or if it stays at 20 PSI..
Reply With Quote
  #6  
Old 03-03-2013, 10:54 AM
mysterync's Avatar
Diesel Bombers Sponsor
 
Join Date: Mar 2007
Location: Blowing Rock,NC
Posts: 3,791
Default

Quote:
Originally Posted by Sudia247 View Post
So it's normal to drop fuel pressure under load? But the fuel filter is new, about 2k miles on it. I removed the fuel heater as well.

I was thinking it could be a failing lift pump, but I wasn't sure, Ill give it WOT and see where it drops to or if it stays at 20 PSI..
As engine rpm increases the lift pump produces more volume so it shouldn't drop much at all past 20. You could raise your baseline pressure up a bit more. If it drops when rpms are raised with no load then you should be looking for issues.

Sent from my DROID RAZR using Tapatalk 2
Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Help please ? 6.5 td lift pump problems Dbleo351 Chevy/GMC 6.2L and 6.5L 19 11-20-2016 09:34 AM
Rough start after oil change. ctjkelley Chevy/GMC 6.2L and 6.5L 7 06-03-2015 06:01 AM
6.2l Banks Turbo - Stalling and Power Loss When Hot RatsMC Chevy/GMC 6.2L and 6.5L 19 05-04-2015 05:25 PM
TROUBLE CODE P1755 ? robbyS 5.9 Liter CR Dodge Cummins 03-07 3 04-16-2015 02:22 PM
PO1218 and slight miss moneypitk5 Chevy/GMC 6.2L and 6.5L 3 02-12-2015 11:01 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 03:46 PM.