LB7: 04 LB7 possible injector issue???

Josh2002cc

Josh2002cc

That Uncle
Apr 2, 2007
1,832
0
0
39
Okay guys need some help. I have a 2004 lb7 with 50,xxx miles on it. The injectors were just replaced and the guy who had it before me installed injectors from some guy on flea bay. Well, now the truck has a miss to it. The balance rates are all within spec but I know there is still something wrong. At idle, the truck shakes and you can really feel the miss.

Is there anyway to test the return flow? Something similar to say the bottle test Simon posted in the DIY section except for a LB7. I know the injectors could still be the problem even though the balance rates are okay.

Thanks in advance.
 
WanaDmaxsub

WanaDmaxsub

Junior Member W/gray hair
Feb 17, 2007
644
1
18
There have been some simple explanations on how to do it posted over on DP. But I don't think they went into great detail. From what I can remember you can test each bank with out taking off the valve covers, but if you want to check each injector then you will need to remove the valve covers. Sorry I can't be more specific than that...
Have you tried disabling each injector individually to see if you can at least figure out which one it is?
 
2500HeavyDuty

2500HeavyDuty

Book 'em, Danno!
Feb 14, 2008
2,209
1
0
Katy, Tx
www.myspace.com
Josh2002cc said:
Okay guys need some help. I have a 2004 lb7 with 50,xxx miles on it. The injectors were just replaced and the guy who had it before me installed injectors from some guy on flea bay. Well, now the truck has a miss to it. The balance rates are all within spec but I know there is still something wrong. At idle, the truck shakes and you can really feel the miss.

Is there anyway to test the return flow? Something similar to say the bottle test Simon posted in the DIY section except for a LB7. I know the injectors could still be the problem even though the balance rates are okay.

Thanks in advance.
Click to expand...

you can test the injectors ive been told, you unplug the return line on the back of the engine and put a graduated cylinder or something like that onto the end to measure the fuel that comes out, and then crank the engine over for 30 seconds. if more than 8ml of fuel comes out u got a injector problem

i cant remember the exact amount of fuel but IIRC it was 8ml
 
TrentNell

TrentNell

Finally underway !!!!!
Jul 7, 2008
7,543
0
0
44
slc tuah
Mike L. said:
Another LB7 that runs bad.:baby: I have one as well. Interesting.
Click to expand...

did you ever get around to checking out that egr ?

and josh i know its a long shot but something to keep in mind have you done a compression check ? and have you checked actual fp vs camand fp to maybe check the regulator .
 
Last edited:
Josh2002cc

Josh2002cc

That Uncle
Apr 2, 2007
1,832
0
0
39
trentnell said:
did you ever get around to checking out that egr ?

and josh i know its a long shot but something to keep in mind have you done a compression check ? and have you checked actual fp vs camand fp to maybe check the regulator .
Click to expand...

I have not checked the compression. I know "they" say bad balance rates can be caused by bent rods, but I know that is not always the case as the last motor I helped tear apart had 7 bent rods...so what does one do you know????:confused:

I do have a compression test kit but would like to rule injectors out first. If I cannot do that and be 100% certain it is just a injector problem,a compression test can/will be done.

To 2500hd:

What is a "graduated" cylinder? I know where the return line ports are at but what is this cylinder you speak of?

To MikeL:

Who would have thought there would be two LB7's with issues? Maybe the truck is okay and it is just me that "thinks" it is the truck who is having issues? :rofl:
 
Last edited:
Josh2002cc

Josh2002cc

That Uncle
Apr 2, 2007
1,832
0
0
39
mytmousemalibu said:
Any fuel in the oil buddie?

Oh BTW, Pump was at my doorstep when i got home :D:hug:
Click to expand...

I got that pump out so quick because I wanted you to have it by the weekend, looks like that worked out okay!

And yes, there is fuel in the oil. Sorry I forgot that part in my OP. \
 
Josh2002cc

Josh2002cc

That Uncle
Apr 2, 2007
1,832
0
0
39
Nice write up, that is for sure. Thank you, that helps a ton.

I still need to find out how to test the return rates by the return line fitting. Anyone?
 
SonicAudio

SonicAudio

New member
Jan 25, 2009
38
0
0
Texas
2500HeavyDuty

2500HeavyDuty

Book 'em, Danno!
Feb 14, 2008
2,209
1
0
Katy, Tx
www.myspace.com
2500HeavyDuty said:
you can test the injectors ive been told, you unplug the return line on the back of the engine and put a graduated cylinder or something like that onto the end to measure the fuel that comes out, and then crank the engine over for 30 seconds. if more than 8ml of fuel comes out u got a injector problem

i cant remember the exact amount of fuel but IIRC it was 8ml
Click to expand...

Correction

Well you gotta unplug the injector harness. and crank the engine over for 30 seconds.

if you got more than 3.5oz. coming out you got weak injectors. but it could also be a leaky injector or bad seleniod. more than 4oz. you got a few injectors with bad bodies. anything beyond that like 6oz. you got many bad injector bodies.
 
Last edited:
Josh2002cc

Josh2002cc

That Uncle
Apr 2, 2007
1,832
0
0
39
Update:

I noticed the fuel filter housing was leaking so I put a spare one I had laying around on and took it for a drive. After driving awhile and we stopped at a friends house hung out for less than 5 mins. Went to start the truck and nothing. Truck would not re-start, we cranked and cranked but nothing. Let the truck sit for about 4 hours, went back and it started up after a short crank.

I am leaning twords injectors are junk or a few atleast are. The thing is, my friend bought these injectors off sleeze bay and now that company is saying they need to test the injectors before they will send out a new set(which I completely understand) but how many companies especially one that sells injectors on sleeze bay have a test stand to test a CR injector?

Next question is, where can I buy a set of injectors besides say a dealer? Any vendors on here sell them?
 
Josh2002cc

Josh2002cc

That Uncle
Apr 2, 2007
1,832
0
0
39
2500HeavyDuty said:

Correction

Well you gotta unplug the injector harness. and crank the engine over for 30 seconds.

if you got more than 3.5oz. coming out you got weak injectors. but it could also be a leaky injector or bad seleniod. more than 4oz. you got a few injectors with bad bodies. anything beyond that like 6oz. you got many bad injector bodies.
Click to expand...

Do I need to do both heads or do is it okay to just test one side? I want to try this tomm. but would like to be sure this is a good testing procedure.

Thanks
 
You must log in or register to reply here.
Top Bottom