Chevy/GMC Duramax 01-04 LB7 Discussion of Chevy and GMC Trucks with LB7 Duramax Turbo Diesel Engines

LB7 tear down

Old Apr 16, 2014 | 10:27 PM
  #171  
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UPDATE PUMPS HERE can't install it till the weekend tho
 
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Old Apr 18, 2014 | 10:00 PM
  #172  
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ok, wow... I just read your whole thread here ... again

Man ... if it weren't for bad luck you wouldn't have ANY LUCK !!!! ..

I sure hope it runs good after all that ... ... waiting for updates...
 
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Old Apr 19, 2014 | 09:43 PM
  #173  
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update got it wrapped up she still won't fire I only tried it 3 times 30 sec etch bleeding etch time my dad was pumping the primer when I was spinning it over I'm not sure if it's not primed yet I did drain all the lines and cleaned again or if it's something else I just can't catch a break on this truck any ideas
 
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Old Apr 20, 2014 | 03:57 PM
  #174  
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Wow.... wish i could come over and help out there ... gonna need some one who knows these engines .... most of the diag is just simple stuff but there manny steps ....

where u at anyways ?
 
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Old Apr 20, 2014 | 05:14 PM
  #175  
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middle of AL and there is no Dmax mechs within 200 miles im kinda hoping shes just not primed yet ive been running a fever of 102.9 so i havent worked on it today i know sometimes they take a long time to prim

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i emailed II to see if they have any advise it will be tomorrow before they get it tho
 

Last edited by Walker.B; Apr 20, 2014 at 05:14 PM. Reason: Automerged Doublepost
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Old Apr 21, 2014 | 10:15 AM
  #176  
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get a clear tube and a container to connect it to. fill it up with clean diesel and plumb it in after the filter. raise the container above the engine. crank the engine over. the fuel level should go down while cranking over. if no then there is something wrong with the lines running up to the CP3. plumbed in wrong, pinched, etc

if it starts then shut off the engine before it runs out of fuel. hook the lines back up, prime and try again



basicly you are bypassing the yellow line and supplying your own
 
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Old Apr 22, 2014 | 07:40 PM
  #177  
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ok thanks I'll try it

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i tried it 2x 30 sec crank time it sucked none of the fuel down and didnt even try to fire how could a brand new pump not pump????????????????????

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update i got it sucking fuel but it wont fire
 

Last edited by Walker.B; Apr 22, 2014 at 07:40 PM. Reason: Automerged Doublepost
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Old Apr 22, 2014 | 09:34 PM
  #178  
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OMW !!!! .. you have to be kiddin

is there a fuel pressure sensor that can fail in the rail ???
 
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Old Apr 22, 2014 | 10:42 PM
  #179  
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there is one its very rare to fail and id have to pull half the top end off again to get to it and its like $280 i dont know what to do next i gotta get a scanner on it has to be building enough pressure new pump new injectors new seals everywhere no leakes and even a shimmed FPRV (the one on the fuel block that returns over pressure) to make sure it wasnt leaky checked every single fuse and relay in the thing what could be doing this it even has a new crank sensor and cam sensor only problem is guy cant come scan it for like 2 months any help at all would be great im about to bite it and tow it to a dealer!
 
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Old Apr 23, 2014 | 02:18 AM
  #180  
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The fuel pressure sensor is actually pretty easy to get to.


If it is faulty then unplug it and the ecm will think it has 26k psi fuel pressure and thus opening the injectors.

With the rails empty and full of air it may take a while to build the pressure needed to fire. When I pulled the rail end cap to add the 2nd cp3 it took many cranks to get it to start. After that I figured out how affective gas is as a starting fluid. I would never add more then about 1oz for safety
 
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