injector return test question

[jpatt]

So in a pinch I need to just replace a couple of my injectors and not all 8 right now. Problem is real long crank before it fires. When I do the return test to figure out which ones are worse off is this correct

Pull return lines from 1 bank.
Run lines to to measuring cups
Crank for 15 seconds.
Repeat other side. Questions are do I leave my lift pump hooked up, it runs as soon as key is on.
And also what do I unhook to keep truck from starting.

 

[Burn Down]

You can do it however you want. I just started my truck and let it idle for 15-20 seconds it was obvious which ones were bad.

 

[jpatt]

So just start it and let idle for 15 seconds. Am I just looking for a few that return alot or what. The cranking way I was looking for 5 ml or less

 

[Burn Down]

My good ones were right at 5ml the 2 bad ones hit 40-50ml.
http://www.duramaxdiesels.com/forum/showthread.php?t=33791

 

[jpatt]

So start it and then count for 15 seconds and shut it down. Hoping I just have a bad one or 2. Not all 8 returning just a tad to much each. Gonna get new return lines before I do it since I hear they are gonna break

 

[THEFERMANATOR]

Theres 2 return rate tests, cranking and enganced where you check it idling. For the cranking test, it's no more than 4 ml per injector or 15 per bank for 15 seconds of cranking with rail at 30-35 mpa. I don't remember the enhanced numbers off the top of my head.

 

[jpatt]

30-35 mpa????
Sorry I'm diesel dumb man

 

[Awenta]

30-35 mpa????
Sorry I'm diesel dumb man

4350-5050 psi


Sent from my iPhone using Tapatalk

 

[THEFERMANATOR]

It's the rail pressure reading. Theres a chart that outlines how much the injectors can return at each pressure. I believe the chart is in the tsb about lb7 injector diagnostics. I know my injectors when I checked them before didn't even return 2 ml for 15 seconds of cranking with rail pressure up around 90 mpa accordi,g to my scanner reading during the test. I unplugged the fca so it would max out because at 35 I wasn't even able to fill the lines to the beakers after 3 15 second starter cycles. I ended having a bad cp3 then, now ai need injectors, but I still don't have a high return problem.

 

[jpatt]

Truck goes on Monday to have injectors and head gaskets done. Hate putting 6k into this thing but hopefully I will have no more issues with the truck.

 

[WVRigrat05]

The fun part of owning a diesel. If it's done right, you won't have to do it again as far as the head gaskets.