GM Engine & Exhaust Performance EFI | GEN I/GEN II/GEN III/GEN IV Engines |Small Block | Big Block |

Fuel pressure low...

Old May 30, 2010 | 08:48 PM
  #1  
5.3 GMC's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2008
Posts: 135
Likes: 0
From: Malvern, AR
Default Fuel pressure low...

At idle my fuel pressure is 44 and only 52 at wot. Walbro 255 in tank is brand new. What can I do to get it back where I need it?
Reply
Old May 30, 2010 | 09:02 PM
  #2  
53bowtie's Avatar
TECH Fanatic
iTrader: (6)
 
Joined: Mar 2007
Posts: 1,614
Likes: 14
From: Detroit, MI
Default

Have you changed the fuel filter in a while?? Also might run some cleaner though in the next tank of gas.
Reply
Old May 30, 2010 | 09:26 PM
  #3  
5.3 GMC's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2008
Posts: 135
Likes: 0
From: Malvern, AR
Default

It's gettin changed tomorrow although it doesn't have more than 10k miles on the one in it now.
Reply
Old May 30, 2010 | 09:53 PM
  #4  
rmck490's Avatar
Teching In
 
Joined: Apr 2010
Posts: 18
Likes: 0
From: Colville, WA
Default

Originally Posted by 53bowtie
Have you changed the fuel filter in a while?? Also might run some cleaner though in the next tank of gas.
If that's not it, maybe the fuel pressure relief valve.
Reply
Old May 31, 2010 | 11:11 AM
  #5  
5.3 GMC's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2008
Posts: 135
Likes: 0
From: Malvern, AR
Default

Where is the fuel pressure relief valve located?
Reply
Old May 31, 2010 | 11:46 AM
  #6  
rmck490's Avatar
Teching In
 
Joined: Apr 2010
Posts: 18
Likes: 0
From: Colville, WA
Default

Originally Posted by 5.3 GMC
Where is the fuel pressure relief valve located?
I meant the fuel pressure regulator actually. I hope that didn't confuse you. It would be on the fuel rail on the driver's side of the motor.
Attached Thumbnails Fuel pressure low...-engine-component-locations.gif  
Reply
Old May 31, 2010 | 05:04 PM
  #7  
5.3 GMC's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2008
Posts: 135
Likes: 0
From: Malvern, AR
Default

Well I changed the fuel filter today and it's still the same. I guess a regulator is next
Reply
Old May 31, 2010 | 10:25 PM
  #8  
53bowtie's Avatar
TECH Fanatic
iTrader: (6)
 
Joined: Mar 2007
Posts: 1,614
Likes: 14
From: Detroit, MI
Default

If you have a gauge to put on the fuel rail you can disconnect the vacuume hose on the top of the fuel pressure regulator and the pressure should go up to 70 ish. Then you know it is the regulator that it bringing it down to the level its at. Also, the regulator could be leaking if the vacuume hose is wet although this normally will make it flood a little not drop pressure.
Reply
Old Jun 1, 2010 | 02:30 PM
  #9  
5.3 GMC's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2008
Posts: 135
Likes: 0
From: Malvern, AR
Default

Swapped out the regulator and got it back up. 52 at idle and 58-60 at wot
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Mossyoakglock
GMT 900 Trucks General Discussion
4
Aug 28, 2015 12:49 PM
noproblems209
Tuning, Diagnostics, Electronics, and Wiring
12
Aug 10, 2015 06:57 PM
05GMC4.8
GMT 900 Trucks General Discussion
5
Aug 7, 2015 09:55 PM
GMCtrk
FORCED INDUCTION
67
Jul 17, 2015 06:39 PM
Mossyoakglock
GMT 900 Trucks General Discussion
0
Jul 17, 2015 08:30 AM


Thread Tools
Search this Thread

All times are GMT -5. The time now is 11:19 PM.