LB7: Having a little trouble with it

[TYREBOYZ_DEMAXIN]

i have a friend with a 2004 GMC LB7 with a PPE Hot,runing a TS MP-8,AirDog 150GPH and a built tranns..
heres what its doing,according to him it starts hard only when cold(IMO it starts kinda hard regardless)but when i say it starts hard i do mean it does start hard when its cold he has to use ether to get it to fire up and even after its warm it still has to crank kinda hard..the truck was at the dealership and they said glow plugs but he convinced them to check the Injectors as well but they said they'er fine but replaced the glow plugs under warranty(lucky him)but the problem is the truck still does it.we checked the AirDogs and they work,checked to make sure we have fuel on the return line and changed the fuel filter.any ideas guys.also if this doesn't make sense just say so and i'll try explaining it again with a different approach.

 

[mainer]

check the balance rates??

 

[TYREBOYZ_DEMAXIN]

from what the dealer said they checked that but im still not convinced the injectors are good.

 

[TYREBOYZ_DEMAXIN]

bump...i would like to hear a few more opinions..

 

[slowlmm]

i have a friend with a 2004 GMC LB7 with a PPE Hot,runing a TS MP-8,AirDog 150GPH and a built tranns..
heres what its doing,according to him it starts hard only when cold(IMO it starts kinda hard regardless)but when i say it starts hard i do mean it does start hard when its cold he has to use ether to get it to fire up and even after its warm it still has to crank kinda hard..the truck was at the dealership and they said glow plugs but he convinced them to check the Injectors as well but they said they'er fine but replaced the glow plugs under warranty(lucky him)but the problem is the truck still does it.we checked the AirDogs and they work,checked to make sure we have fuel on the return line and changed the fuel filter.any ideas guys.also if this doesn't make sense just say so and i'll try explaining it again with a different approach.

mabey reluctor wheel bad crank or cam sensor mabey ? have you tried puting a stock tune in? and if so is it the same result ?

 

[TYREBOYZ_DEMAXIN]

it does it with a stock tune on it..is there a way i could log it with my EFILive and tell?

 

[slowlmm]

tech 2 is the only way i know of

 

[bigdog33]

Isn't ether bad on a common rail?

 

[mytmousemalibu]

If rail psi is low it will do that, when i lost an injector it would take alot of cranking to get it to fire, check to see if theres raw diesel in the oil. if your not sure grab a regular piece of paper and drip a few drops of oil on it in differant spots. if theres any significant amount of diesel in the oil it will bleed out into the paper and the oil will stay on top without soaking in.

Also:
Air in fuel system? drawing it in?
Restriction in fuel system
bad injector (s) ....can leak internally into motor
low rail psi
Any codes?
low compression?


just a few ideas for ya

 

[TYREBOYZ_DEMAXIN]

i hooked it up to my flash scan and no codes but i wonderd if it wasn't low rail pressure myself caused by a faulty Injector,if i could get the dealership convinced that an injector is bad i'm perty sure that would cure the problem..

thanks for the ideas guys i'm gonna try a few ofem and see what we come up with..again thanks.Later James

PS i should mention,even with the truck plugged in it still starts about the same and it has new glow plugs.

 

[Lennart]

If you have EFILive you could log with the attached PID files.
Please post your log files, this way we can possibly help.

 

[TYREBOYZ_DEMAXIN]

i'll have to see how soon i can have the truck to do this..

 

[JOHNBOY]

What I would do is log actual rail pressure while tryng to start the truck. You need at least 1500psi to get it to start while cranking. To do this correctly you need to remove the TS MP8. Honestly he should sell that thing they cause nothing but trouble IMHO.

 

[TYREBOYZ_DEMAXIN]

i havent had time to hook the scan tool to the truck yet but he just got back from another dealer and they are saying its the CP3 going bad and its gonna cost $1500 to replace..this is the 2nd LB7 that i had to fight with the dealers to get the injectors changed.the 1st one they tried to tell me he had a fuel line leaking between the tank and fuel filter..i'm getting realy sick of it..heads are gonna start rolling

thanks again guys for all the suggestions,i'll have the truck tomorrow afternoon so i'm going to see what i can figured out.

 

[j johnson]

dont use ether to start your trk. try wd40 starts as good as ether and will lube as it works!! once you get a trk. used to ether it will become an ether baby...no mater what you do it will need ether to start!!

 

[JOHNBOY]

i havent had time to hook the scan tool to the truck yet but he just got back from another dealer and they are saying its the CP3 going bad and its gonna cost $1500 to replace..this is the 2nd LB7 that i had to fight with the dealers to get the injectors changed.the 1st one they tried to tell me he had a fuel line leaking between the tank and fuel filter..i'm getting realy sick of it..heads are gonna start rolling

thanks again guys for all the suggestions,i'll have the truck tomorrow afternoon so i'm going to see what i can figured out.

Honestly I think that injectors are replaced to often. I have been around more trucks that did not need them then that really did. You still need to get a log and check balance rates with the MP8 removed not just off. I would not be suprised if that thing has a lot to do we the issues.

 

[racinmike77]

Stacked tuners, maybe too much timing??

 

[TYREBOYZ_DEMAXIN]

the MP8 only adds fuel rail pressure,he never showed up with the truck sat. he was working so i never did anything with it..i told him to take the MP8 off and see what happens.

 

[TYREBOYZ_DEMAXIN]

ok we got the TS taken off and same problems,hard start..havent had the truck yet to hook it up but right now he has a chance to buy a LMM CP3 pump for very cheap my question is will they work on a LB7..we will be running EFILive on the truck as soon as we get the problem figured out.

 

[racinmike77]

yes. If you use the new lbz/lmm regulator you need to plug it in before you bolt it down, but it will work