[Joe Buck]

does the LBZ have a injector pump and is It mechanical or eletrical and where is It.:confuzeld

 

[rock_shoes]

High pressure common rail I believe. Everything is controlled at the injector. The control module dictates when the injector opens, how long it opens for ect.

 

[DURAtotheMAX]

good luck finding it

 

[bruins499]

The injection pump is stuck under everything in the center of the intake valley.....and is gear driven.

 

[JoshH]

There is no injector pump in the traditional sense of the term. As rock shoes pointed out there is a high pressure fuel pump that feeds fuel rails. The injection timing and duration is controlled by the ECM directly at the injector.

 

[DURAtotheMAX]

The theory/function of the Bosch HPCR system on the duramax's is basically similar to any modern gasser sequential-fire port fuel injecton system. All of the injectors are fed by a common pressurized fuel rail. The pressure of the feed rail can be raised and lowered (electronically) independant of engine speed. The fuel injectors are wholly fired and timed by the ECM. (same as a SFI gas engine, timing and pulse width is completely ECM controlled) The "injection pump" per se on the dmax is gear driven off the cam gear and its only purpose is to act as a simple high pressure pump to keep the fuel rails pressureized with sufficent fuel to satisfy the demands of the commanded injector pulse width by the ECM.

ben

 

[Walstib52]

LBZ injector pump

I replaced mine last fall.
It's a mechanical pump driven off of the cam gear. It sits in the front of the valley of the V-8 behind the water pump. Takes the removal of a whole lot of stuff to get to even seen it much less remove it.

Major PITA and very expensive. See my post at http://www.dieselplace.com/forum/4667623-post9.html
if you're interested.

 

[Maine Towing]

Technically it is known as a CP3. On the LBZ there is no longer a "lift pump" which pushes fuel up to the injection pump, instead the CP3 does all the work of drawing fuel from the tank and then increasing the pressure to the common rail - it does a lot of work. If you are standing in front of your truck look behind the oil fill tube, you can see where the feed lines coming from the "common rail" disappear into the valley, they end at the IP. Installing a simple 12V lift pump will help your CP3 live a longer and happier life and assist with the dreaded P0087 code.

 

[Walstib52]

Lift pump?

Technically it is known as a CP3. On the LBZ there is no longer a "lift pump" which pushes fuel up to the injection pump, instead the CP3 does all the work of drawing fuel from the tank and then increasing the pressure to the common rail - it does a lot of work. If you are standing in front of your truck look behind the oil fill tube, you can see where the feed lines coming from the "common rail" disappear into the valley, they end at the IP. Installing a simple 12V lift pump will help your CP3 live a longer and happier life and assist with the dreaded P0087 code.

I presume you're talking about installing an electric fuel pump somewhere in the fuel supply line between the tank and the fuel filter assembly. This would presumably increase the fuel pressure on the suction side of the pump. However, since the "CP3" is a mechanical pump driven by the cam gear, so its rpm is proportional to engine speed, its lifespan would be a function of engine hours/engine speed. You must believe that the "lift pump" reduces the workload of the CP3 thereby extending the lifespan. I don't understand how raising the pressure on the inlet side will affect lifespan of the mechanical pump. Unless of course, cavitation occurs at the pump somehow causing a momentary loss of lubricity from momentary fuel flow interruption.

Not trying to be a smartass here, but I'm a technical guy and question things that I don't fully understand. Bottom line - What is the rationale for adding the "lift pump" and what evidence do you have that it actually makes a difference.

 

[Maine Towing]

I don't think the lift pump increases the pressure at the CP3 as most lift pumps run around 12 - 14 psi, however it does reduce the work load on the CP3. Given the CP3 has to suck fuel from the tank, through the filter and into the high pressure side of the system, probably 16 or so feet worth of line on a crew cab the opportunity for cavitation is probably much higher. I can't remember the exact distance but there is a physical limitation of just how far a liquid can be drawn up, (30 something feet I think) due to the effect of gravity and pressure drop, therefore it is harder to draw or suck a liquid a longer distance, add in a fuel filter and the laws of physics begin to apply. Now on the other hand, one can push a liquid an indefinite distance, and through any obstacle with enough pressure - think water jet - which would be the function of a lift pump. So yes, perhaps the CP3 experiences loss in lubrication as a result, or it just does not get enough fuel as the delivery rate is reduced as the pump begins to wear from normal operation, either way around 200,000 towing miles and most CP3's are showing their age, mine was there at 175,000 miles - I would get a P0087 under load frequently. After a bunch of research I installed a lift pump and got to 300,000 miles before it was time for a new CP3 - just my personal experience.

 

[willydmax]

I don't think the lift pump increases the pressure at the CP3 as most lift pumps run around 12 - 14 psi, however it does reduce the work load on the CP3. Given the CP3 has to suck fuel from the tank, through the filter and into the high pressure side of the system, probably 16 or so feet worth of line on a crew cab the opportunity for cavitation is probably much higher. I can't remember the exact distance but there is a physical limitation of just how far a liquid can be drawn up, (30 something feet I think) due to the effect of gravity and pressure drop, therefore it is harder to draw or suck a liquid a longer distance, add in a fuel filter and the laws of physics begin to apply. Now on the other hand, one can push a liquid an indefinite distance, and through any obstacle with enough pressure - think water jet - which would be the function of a lift pump. So yes, perhaps the CP3 experiences loss in lubrication as a result, or it just does not get enough fuel as the delivery rate is reduced as the pump begins to wear from normal operation, either way around 200,000 towing miles and most CP3's are showing their age, mine was there at 175,000 miles - I would get a P0087 under load frequently. After a bunch of research I installed a lift pump and got to 300,000 miles before it was time for a new CP3 - just my personal experience.

Great explanation. According to Kennedy Diesel (and I believe him) with a lift pump your fuel filter always stays completely full whereas without one it doesn't always. If you don't believe it cut your fuel filter open and see if the contamination is uniform. Even if the lift pump doesn't help anything live longer it sure makes for easier fuel filter changes:thumb:

 

[skmct]

I am going to keep this as simple as I can. The media being pumped also acts as a lubricant between the rotor and the stator. Wear is caused when that lubricant fails or is not present. Air in the media causes voids in the lubricant film witch causes the wear. A lift pump should reduce the amount of air in trapped in the media.

 

[Walstib52]

Thanks for your thoughts on the matter. To your knowledge, what kind of pump are most people using and where in the system do they typically install it? What circuit do they tap into to power it?

 

[306LBZ]

http://www.kennedydiesel.com/docs/BasicLiftPumpInstallation.pdf

I plan on purchasing this one day, he has a dual pump option too. Some guys use Airdog's other's I've seen on here are PPE, Raptor, etc. If you search everyone has their opinion but Kennedy's seems like a good all around and simple install piece that can be put back to stock if needed for whatever reason, so I will buy his when the time comes to purchase.

 

[blkdmax05]

Thanks for your thoughts on the matter. To your knowledge, what kind of pump are most people using and where in the system do they typically install it? What circuit do they tap into to power it?

Do a search, youll find hundreds of threads on the subject. Most use Kennedy or Air Dog.

 

[IGO1320]

X2 on the Kennedy pump.

 

[glenns]

If I remember right someone posted once, or I read an article that the CP3 and Bosch injectors are from the heavy duty line of products and rated for some high mileage/hours no?

I put on a FASS at about 180k...am at 261k now and all heavy towing. I would like to see 400k plus out of the CP3 and injectors, I know others have gone longer.

 

[Saltfever]

edit . . . Even if the lift pump doesn't help anything live longer it sure makes for easier fuel filter changes:thumb:

Huh? How does it make it easier? Or do you mean you don't have to pump the filter to get the air out because the lift pump is displacing air with fuel?