Duramax Diesels Forum Truck of the Week
  #1  
Old 07-08-2012, 10:24 AM
joshpete joshpete is offline
FNG
 
Join Date: Jul 2012
Posts: 8
Default HELP! low rail pressure, new cp3 no start

i bought a 2001 duramax. 260000 miles from a guy. the only way itll start is if you give it a shot of either an then it fires right up and runs great. anyways i know the problem is because when crankin it over the rail pressure is only at 600-700 psi an i need 1500. i didnt know if it was a problem with lines goin to the cp3 so what i did was hooked a line directly to the cp3 and filled it with fuel while holdin it straight up an down. still no start i then took an air compressor and pushed air into the line while crankin it over. this made it start.

i then ordered a new fuel filter housing an replaced all rubber lines and it started for like 10 times without either. (i did have to crank it over a little exta long it seemed like tho) anyways, like after the tenth time of starting it it went back to not starting unless i use either.

i then decided maybe its the cp3. somethin is prolly wrong with it an maybe its having trouble sucking fuel. i replaced it with a new one and finally got it all back together and primed the lines and it fired up. i shut it off and it started back up again. it did seem to crank a lil longer than normal tho. i then drove it around and bout the tenth time i went to start it, it wouldnt start! the fuel rail pressure wont get past 700 psi. i need help!! im using an Edge to monitor the fuel pressure
Reply With Quote
  #2  
Old 07-08-2012, 10:28 AM
TeaBagger2006's Avatar
TeaBagger2006 TeaBagger2006 is offline
Im a Garrett Nut Swinger
 
Join Date: May 2008
Location: vegas
Truck: CC/LB
Engine: LBZ
Transmission: Automatic
Posts: 2,895
Default

Have you checked your balancerates when it's running? More than likely it's the injectors
__________________
Joe
Loosest Tailgater in USA
2006 GMC 3500 D/A LBZ SRW CC/LB SLT 4x4
8" Fabtech lift 355/60/20 tires....some go fast goodies
13.20@106mph
Reply With Quote
  #3  
Old 07-08-2012, 10:58 AM
Noreaster's Avatar
Noreaster Noreaster is offline
Hotrodder

 
Join Date: Jun 2007
Location: Cape Cod,MA
Truck: 2002 GMC
Engine: LB7
Transmission: Automatic
Posts: 2,722

Default

be careful with the ether, seen alot of bad stuff happen from using it
__________________
02 GMC 2500HD RC/LB 12.26 @ 109 "No Shuckin Luck"
Ridge Runner Diesel Performance, Big Dipper tranny, Profab Performance, Super Diesel, Creatures of the Night, AirDog, BD
02 GMC 2500HD EC/SB WCFab twins
Bay State Diesels
Reply With Quote
  #4  
Old 07-08-2012, 11:17 AM
Hot COCOAL's Avatar
Hot COCOAL Hot COCOAL is offline
May the farce be with you
 
Join Date: Jun 2012
Truck: CC/SB
Engine: LBZ
Transmission: Automatic
Posts: 3,502

Default

Ok ok . So im on a frprv(fuel rail pressure relief valve) kick
Only cuz i just helped a guy that owns an lly with a similar problem, just before the 4th
his truck had been experiencing rail pressure codes tho, but it became increasingly more difficult to start, to the point where it would only start "after" it sat for a bit, like hours.
i explained to this guy how the fprv worked, skeptical, this guy let me work on his truck in my garage, i put a shim and ported rail fitting on his truck, he was running an edge programmer, i thought an efi live program would be better, gave him robs name, forum address.
Greg's truck started right up, he has my number, hasn't called back to say anything is wrong, so ill take that as a job well done, he should be coming home tonight so I'll try to get feedback as to weather or not we fixed his problem
his only gauges were on his edge so i never knew what rail pressure he had
All that back story to say, it wont hurt to, and is inexpensive to install the frprv shim
idk if it will even help at all, some may yell and say its a dumb idea, but ya never know, weird chit happens.
Reply With Quote
  #5  
Old 07-08-2012, 11:18 AM
Hot COCOAL's Avatar
Hot COCOAL Hot COCOAL is offline
May the farce be with you
 
Join Date: Jun 2012
Truck: CC/SB
Engine: LBZ
Transmission: Automatic
Posts: 3,502

Default

Quote:
Originally Posted by Noreaster View Post
be careful with the ether, seen alot of bad stuff happen from using it
X100 ether on a dmax or any modern diesel for that matter is a huge no no
Reply With Quote
  #6  
Old 07-08-2012, 11:55 AM
redws6rocket's Avatar
redws6rocket redws6rocket is offline
Hotrodder
 
Join Date: Apr 2007
Location: Odessa, MO
Truck: 2006 ECSB 3/4 ton
Engine: 6.6L Duramax
Transmission: Automatic
Posts: 499
Default

Sounds like you have injector returning to much fuel to me
__________________
2001 ECSB Built Motor/Trans 2.5 Puller
Special Thanks Mike Bodine, Danville Performance, Caleb 05LLY, Rick Lance, Precision Converters, Exergy, MA, MPE, RSE Fab, Broviak Tuned
Reply With Quote
  #7  
Old 07-08-2012, 12:03 PM
Subman's Avatar
Subman Subman is offline
Old Geezer
 
Join Date: Jun 2008
Location: Madras, Oregon
Truck: 06 Chev EC/SB
Engine: 6.6 LBZ
Transmission: Automatic
Posts: 3,113

Default

Quote:
Originally Posted by Hot COCOAL View Post
X100 ether on a dmax or any modern diesel for that matter is a huge no no
Totally agree, you can get a run away and scatter your engine in a heartbeat. Try unplugging the Fuel Pressure regulator on the back of the CP it should max out the rail pressure when you start it and make a funny quacking sound. If it does then you know your cp is good. I can't see the fuel pressure relief valve causing your problem, that usually only happens when you are commanding high rail pressure. You could clamp off the rubber fuel return line coming from the relief and see if it starts easier just to eliminate that as well. I have never had any issues doing this, infact raced White Out that way one day when my pressure relief valve was leaking and I couldn't hold rail pressure at WOT.

Could be injectors a balance rate test is a good thing to start with. Any white smoke at idle when you get it running? If so then could be injectors or (hate to say it) bent rods. Bent rods cause lower compression and can make for a hard start. Just a few ideas.
__________________
2007 LBZ Classic
Idaho Rob ATP tuning, MPI twin turbos
Reply With Quote
  #8  
Old 07-08-2012, 12:12 PM
Hot COCOAL's Avatar
Hot COCOAL Hot COCOAL is offline
May the farce be with you
 
Join Date: Jun 2012
Truck: CC/SB
Engine: LBZ
Transmission: Automatic
Posts: 3,502

Default

Nice tips subman. Thanks
Reply With Quote
  #9  
Old 07-08-2012, 12:20 PM
Stingpuller's Avatar
Stingpuller Stingpuller is offline
The Pusher Man
 
Join Date: Jan 2007
Location: central Ohio
Truck: 06 rclb lbz
Engine: diesel D-max
Transmission: Automatic
Posts: 1,919

Default No start

You need injectors. When the fuel is cool it will make enough pressure to start. When the fuel gets hot it thins out and will not make pressure. Ramping up the pressure at idle will not tell you everything because there is little fuel demand and the pump is turning fast enough (idle rpm) to make pressure. Without doing a return test (very hard on lb7) it's hard to tell for sure.
__________________
2007 GMC c4500 Regency Western Hauler 235" Powerflow Dragster Powerflow, Howards rods,Arias piston,Fleece custom daul CP3, Fleece custom 80mm single turbo, Fleece injectors, 9" rear end, SoCal Diesel, Hughes powerglide, Mike's Race Wiring, Fuelabs pump, Ny-trex nitrous, Isspro gauges
Reply With Quote
  #10  
Old 07-08-2012, 12:21 PM
LWATSON's Avatar
LWATSON LWATSON is offline
future trans limpers
 
Join Date: Jul 2008
Location: Scotland Neck NC
Truck: 2006 Silverado CC/SB
Engine: LBZ
Transmission: Automatic
Posts: 2,504

Default

Quote:
Originally Posted by Hot COCOAL View Post
Ok ok . So im on a frprv(fuel rail pressure relief valve) kick
Only cuz i just helped a guy that owns an lly with a similar problem, just before the 4th
his truck had been experiencing rail pressure codes tho, but it became increasingly more difficult to start, to the point where it would only start "after" it sat for a bit, like hours.
i explained to this guy how the fprv worked, skeptical, this guy let me work on his truck in my garage, i put a shim and ported rail fitting on his truck, he was running an edge programmer, i thought an efi live program would be better, gave him robs name, forum address.
Greg's truck started right up, he has my number, hasn't called back to say anything is wrong, so ill take that as a job well done, he should be coming home tonight so I'll try to get feedback as to weather or not we fixed his problem
his only gauges were on his edge so i never knew what rail pressure he had
All that back story to say, it wont hurt to, and is inexpensive to install the frprv shim
idk if it will even help at all, some may yell and say its a dumb idea, but ya never know, weird chit happens.
CoCo Puff you need to get off the fprv kick! LLY's 05 and down did seem to need them more but the 06+ LLY, LBZ, and LMM trucks dont have the problem as often. I have over 180k miles on my truck and 170k of them are over 500 HP. I still havn't installed my shim kit, it is in my glove box and I will not risk damaging my fuel rail until I know I need the shim kit. Good advise to new members would be to do a bottle test to see if they need the shim kit instead of just throwing one in.
__________________

Landon-2006 Silverado CCSB 4X4 LBZ
DA trans with billet input
PI/DA High Stall converter
BT Diesel works lockup controller
EFI Live by Diesel Addiction
Billet S475
Exergy 60's
RDL pedestal
custom Y-bridge
EGR delete
3" boost tubes
Fuelab lift pump
cognito pitman and idle arm braces
tierod sleeves
Watson Fab traction bars
Banks 4" exhaust

8.04 @ 83.74- 1.72 60' best 1/8th with stock turbo
7.81 @ 85.60- 1.61 60' best 1/8th with S475 and drag radials.
Reply With Quote
  #11  
Old 07-08-2012, 01:00 PM
Hot COCOAL's Avatar
Hot COCOAL Hot COCOAL is offline
May the farce be with you
 
Join Date: Jun 2012
Truck: CC/SB
Engine: LBZ
Transmission: Automatic
Posts: 3,502

Default

My valve popped around 128k
i had only been running a tune for 4k miles
at the time i had no idea my tune could cause the frprv to open
one time i commanded full fueling @ w.o.t in my efi race tune and it wasnt pretty, the unexpected loss in power put me in a dangerous position
since then i have been sorta an advocate to anyone running a tune, especially if a tune has been leaning on the frprv spring for a while.
Sorry, but i dont know how, or that you could damage your fuel rail by installing/running the shim.
Making a pass on some one and popping your frprv can have bad consequences too tho.
I apologise for passing along potentially bad advise, it is just an opinion after all. I like to try and take preventive measures, not wait for things to happen.
I build custom homes, when i have to wear a safety harness on a roof, i like to make sure that i have less slack in my rope than height off the ground, i have actually seen a guy fall off a roof and hit the ground while tied in. He looked pretty dumb.
Reply With Quote
  #12  
Old 07-08-2012, 01:26 PM
hondarider552's Avatar
hondarider552 hondarider552 is offline
Getting faster

 
Join Date: May 2008
Location: Arizona
Truck: SC/SB
Engine: Isuzu 6.6 LB7
Transmission: Automatic
Posts: 8,626

Default

Can I buy your oem cp3?
__________________
2003 RC/LB.
10.57 @ 133.88 N2O
Mike L trans

06 RC/LB 4x4 DD/Tow truck


2014 Cruze TD 2.0 DD


Tailgate Crew Member #3
Reply With Quote
  #13  
Old 07-08-2012, 05:25 PM
joshpete joshpete is offline
FNG
 
Join Date: Jul 2012
Posts: 8
Default

ya ima stop using the either.. anyways the edge shows that the balance rates are all good.

i unhooked fuel pressure regulator an then squirted a lil wd40 in to get it started (not sure if thats a good idea either?) it had bout 26000 psi. if i shut it off i could watch the rail pressure drop and if i tried starting it before it got to like below 10000 psi it would start up with no help otherwise it would need help.

i unhooked the fuel return line at that quick coupler on the drivers side and if i pump up that hand primer on the fuel filter it makes fuel slowly come out that line. is this normal? or is there a valve thats suppose to hold the pressurized fuel in?

dont think theres any fuel in oil. once in a great while i may see a lil white smoke coming from the exhaust if i let it set and idle for awhile but its barely any at all. if i run the truck hard or for awhile i smell like burning oil on the exhaust but i dont know where its comin from. could be from the tranny or motor i spect or possibly even diesel fuel?

it looks like theres two different fuel return lines on these motors? one goes to that quick disconnect but the other goes like back behind the motor but i have no idea what its for.

if it is an injector is their anyway to tell which one it is? im gettin fed up with this truck. sorry bout all these questions guys.
Reply With Quote
  #14  
Old 07-09-2012, 05:11 AM
redws6rocket's Avatar
redws6rocket redws6rocket is offline
Hotrodder
 
Join Date: Apr 2007
Location: Odessa, MO
Truck: 2006 ECSB 3/4 ton
Engine: 6.6L Duramax
Transmission: Automatic
Posts: 499
Default

The best way is to use the tubes and lines that come in the Kent Moore kit, one screws in to one head and the other line in the other head. So you have one hose screwed into to each where the fuel returns out. You will crank the motor over for 15 sec. and they should be the exact, the one that is higher is your problem bank. This is a hard test to set up, you pretty much have to take the engine harness loose to get to the fuel lines. You have got an injector returning to much fuel bud, lb7s are known for it.
__________________
2001 ECSB Built Motor/Trans 2.5 Puller
Special Thanks Mike Bodine, Danville Performance, Caleb 05LLY, Rick Lance, Precision Converters, Exergy, MA, MPE, RSE Fab, Broviak Tuned
Reply With Quote
  #15  
Old 07-09-2012, 05:26 AM
ripmf666's Avatar
ripmf666 ripmf666 is offline
Super Moderator
 
Join Date: Sep 2006
Location: Wentzville Mo
Truck: 2006 2500 HD ex cab
Engine: Duramax 6.6
Transmission: Automatic
Posts: 16,057

Default

Post 287 and down will give you the rates of return and how to do the return test.
http://www.duramaxdiesels.com/forum/...?t=6199&page=8
__________________
Devil Girl 2006 2500HD LBZ Ex-Cab 4x4
EFI Live Shine,MPI twins intalled by BigDipper,PPE dual cp3,PPE lift pump,BigDipper 30% injectors, BigDipper Trans Precision ML converter.
Alot Of thanks To George aka BigDipper
11.53 @ 116.92 1.66 60's
RIP LBZ 6/1/08@5:44pm she was strong
She's Alive again
Born on July 27, 2008, 11:59:02 PM


Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

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

Forum Jump


All times are GMT -7. The time now is 10:24 PM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
vB.Sponsors