lly injector return rates

[duramaxxer]

Hey guys. New to the site... Having issues with my 2005 lly.
1093 code when under load at highway speeds. Replaced the filter and housing assembly. Replaced relief valve. Replaced rubber hoses to and from fuel filter. Conducted bottle test, no fuel present at relief valve after cycling under load. Used scantool to command 25k psi (160mpa) and it wouldn't produce more than 13,500 psi. Ran injector return test, less than 2 ml return from each of all 8 injectors... tested while cranking, ficm disconnected, 15 seconds each injector. However, on each bank, there was 42ml that came from the return line, which was disconnected from all injectors as well as the relief valve.... Any ideas?

 

[whytry]

Only one other place it can be returning from ....cp3

 

[duramaxxer]

That's what I'm afraid of... One more note... There was 5 inches mg vacuum at idle, and at wot it increased to nearly 10 inches... Would this also indicate possible air in the low pressure side?

 

[Veikra]

same symptom with mine 2005 lly. But it'd loud at time, not the best soft rolling sound of duramax. So Im betting injector as they are original.

If it's your pump, that's a lot less expensive than all 8 injectors in my case So youre in luck !

 

[1953drtelco]

Subscribing

 

[THEFERMANATOR]

Pump should return less than 1.2 ounces(20ML) of fuel for 15 seconds of cranking, anymore and the rings in it are shot. The high vacuum could be caused by your fuel filter. I've seen a few here lately that didn't have the nub in the middle to release the checkball in the filter head, and were causing high vacuum. All of them were plastic filters, but a friend had a metal one that did it to him.

 

[duramaxxer]

Thank you all for the replies! I have been looking for a spec on the return flow from the pump, unsuccessfully. That 1.2 oz spec... Where might I locate a procedure for determining this value?... I simply ran a hose from the end of the injector return line to a bottle. All injectors were disconnected form it and the fittings all blocked. It was disconnected from the pop off as well, and that lead was blocked. Is this a sufficient test?

 

[THEFERMANATOR]

Take the rubber line off the top of the CP3, this is the return for what leaks past the rings and such internally. Run it into a jar and crank the engine for 15 seconds. If you have more than 1.2 onces(20ML), then the CP3 is done. That rubber return line is basically like a crankcase vent for an engine to allow it to return what fuel leaks past the pistons and sealing rings internally. If it returns to much fuel, the ONLY thing that can cause it is piston wal damage internally to the CP3.

 

[duramaxxer]

Right on. Ill check it as soon as I get home today. Muchas gracias amigo!

 

[duramaxxer]

The return line is directly beneath the feed line from the fuel filter?

 

[duramaxxer]

Or is it under the coolant elbow

 

[duramaxxer]

4 ounces of fuel in 15 seconds of cranking. Cp3 it is

 

[Brent@LDS]

I would agree, looks like you found your culprit. If you need a CP3 let us know and we would be more than glad to help!

http://lincolndieselspecialties.com/i-21817946-duramax-cp3-injection-pump-2004-5-2005.html

 

[THEFERMANATOR]

4 ounces of fuel in 15 seconds of cranking. Cp3 it is

Yeah, I'd say it's DONE! Last one I did returned 3 ounces, and it wouldn't hold more than 13K for rail pressure on a mild tune.

 

[Veikra]

THANK YOU so much for the specs of the pump. I have this to check as well as injector returns. ( I have no ways of checking balance rates )

 

[duramaxxer]

Replaced the cp3. Still returns a ton of fuel with 15 seconds crank. Still throws code... One shop I spoke with said I should do an enhanced injector test... Check injector return while commanding 160 mpa....thoughts?

 

[duramaxxer]

Replaced cp3, same test results after. 5 oz fuel from pump return after 15 sec cranking. Reman pump from diesel store.com.

 

[Burn Down]

Replaced cp3, same test results after. 5 oz fuel from pump return after 15 sec cranking. Reman pump from diesel store.com.

If your doing the test properly as THE FERMANATOR told you, then your new pump is crap... Who the heck is the diesel store? I only use the vendors on this site because there products are trust worthy and I don't like doing jobs twice...

 

[duramaxxer]

I ran the test as described. I still haven't been able to find the spec for it, however... Would it be wise to run an enhanced injector return test to determine if the injectors are failing at higher pressures? Still waiting for a return call from warranty dept at diesel Store. Thanks

 

[duramaxxer]

Also, i plan to purchase a scan tool to read balance rates and monitor fuel pressures, as well as command fuel pressures, etc. Will standard obII capabilities work, or do I need a specific type of tool? Please... Any advice is helpful!