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dukeofurl

6.5 v Duramax fuel pump question

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I know the injector pumps on the old 6.5's went bad a lot - is GM still using an injector pump on the new duramax series of engines or did they eliminate that part altogether? I was able to locate some information here and there, but nothing to answer the question.

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I know the injector pumps on the old 6.5's went bad a lot - is GM still using an injector pump on the new duramax series of engines or did they eliminate that part altogether? I was able to locate some information here and there, but nothing to answer the question.

 

 

 

 

The pumps them selves on the '94-2000 6.5's didn't go bad it's the electronics or the Pump Mounted Driver that does. I had one last 100,000 miles I changed out the PMD and have relocated it out of the engine bay. I am still running the same pump, I have 175,000 miles on the pump so far not too bad of service. The DuraBux IP is much more complicated than the 6.5 pump and is not the same critter. IP don't seem to be an issue with DBux but with some years Injectors are and they cost about $600 a pop.

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They are totally different animals. I have replaced many 6.5 pumps. The driver on the side of the pump does go bad from time to time. The optic sensor inside goes bad more often. Lift pumps are often overlooked for running problems. Timing should be set as close to -.97 as possible. A D-Max pump does nothing more that supply pressure (24,000 psi)!!! All the timing is done by modules. It is much more precise. Be careful of the early D-Max's with the injectors under the valve covers that are out of warranty. Big money to replace. They leak into the crankcase diluting the oil causing low oil pressure and leaks.

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arent the duramax diesel a common rail system, that dont use injection pumps...

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arent the duramax diesel a common rail system, that dont use injection pumps...

 

 

 

 

 

hmm...then how do you build any fuel pressure...?

 

the duramax has a HPCR fuel injection system. heres how it works (basically)

 

there is a Bosch CP3 injection pump mounted on the front of the engine, in the valley, its gear driven off the cam gear. Its a two piston pump, a high side and a low side. The high side compounds the pressure generated by the low side. How much pressure is produced by the pump is depndatn on engine RPM. There is a fuel pressure regulator (electronicly controlled) on the back of the CP3 that can dump pressure as needed, to maintain the rail PSI thast commanded by the ECM.

 

the CP3 sucks fuel from the tank (there is NO lift pump or in-tank pump), and pressureizes the driver side and passenger side fuel rails. On the LB7 dmax's, the driver and pass side fuel rails are fed from the CP3 directly. On the LLY dmax's, the CP3 feeds the driver side rail, and the pass side rail is fed off of the driver side rail. There is also a fuel pressure releif valve that dumps back into the fuel tank, should pressure get above ~25,000 psi. The LB7 and LLY's use different plumbing, injectors, and releif valves. This is why LLY's have P1093 problems, and LB7's dont. So based on engine RPM and fuel press reg setting, the CP3 pressurizes the rail constantly with X psi. At idle its around 4500 PSI. The pres reg dumps most of the fuel back into the fuel tank, because even at idle, the CP3 can produce much more PSI, just not much volume. The injectors are each controlled individually by the ECM. The ECM has direct and complete control over the timing and pulse width of each injector. This is why HPCR systems are so versitile, easy to control, and easy to get power out of. There are NO limitations as to when an injection event occurs, and how long it lasts. It works basically like a gasoline port fuel injection system, with a pressurized common fuel rail feeding all the injectors... But then as engine RPM increases, obviosuly more fuel is needed, so the ECM commands the fuel press reg to allow more pressure in the rail. 23,055 or 160mpa is the rail pressure at wide open throttle. (the 2006 LBZ runs 26,000 psi)

 

the injectors on an LLY and LB7 are driven by the EDU/FICM (silver box on the pass side valve cover). LB7 injectors operate on 96volts, LLY's at 48volts. Because of the high voltage and power required to operate the injectors, the ECM (whch operates on 12 volts) can "directly" drive the injectors, so it has a slaved relay/control module called the EDU/FICM (engine drive unit/fuel inj control module). The EDU receives various injector commands over the J1939/CAN bus from the ECM, and controls the injectors in whatever way teh ECM tells it to. It is a big transformer and switch box kind of... It has fuel running thru it to keep it cool, because of the heat generated by the electrical switching and transforming. 2006 LBZ injectors operate on 12 volts, so they are driven directly by teh ECM. There is no EDU/FICM on a 2006 LBZ.

 

basically thats how it works, without going into boring detail. :crazy:

 

Ben

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arent the duramax diesel a common rail system, that dont use injection pumps...

 

 

 

 

 

hmm...then how do you build any fuel pressure...?

 

the duramax has a HPCR fuel injection system. heres how it works (basically)

 

 

 

 

 

I thought they used HEUI type injectors where high pressure oil acts as the injection power... like on the new cummins and 7.3/6.0 DI powerstrokes.

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arent the duramax diesel a common rail system, that dont use injection pumps...

 

 

 

 

 

hmm...then how do you build any fuel pressure...?

 

the duramax has a HPCR fuel injection system. heres how it works (basically)

 

 

 

 

 

I thought they used HEUI type injectors where high pressure oil acts as the injection power... like on the new cummins and 7.3/6.0 DI powerstrokes.

 

 

 

 

 

no.

 

cummins has never used HEUI either.

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arent the duramax diesel a common rail system, that dont use injection pumps...

 

 

 

 

 

hmm...then how do you build any fuel pressure...?

 

the duramax has a HPCR fuel injection system. heres how it works (basically)

 

 

 

 

 

I thought they used HEUI type injectors where high pressure oil acts as the injection power... like on the new cummins and 7.3/6.0 DI powerstrokes.

 

 

 

 

 

no.

 

cummins has never used HEUI either.

 

 

 

 

 

Oh my bad. :cheers:

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it's a ford/cat and couple other makers thing hydrolic electronic unit injection. good system pain to service though. some benifits and some cons like anything else.

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common rail fuel injection uses a high pressure pump to create the pressure for injection and the injectors are simply electronically controlled sprayers that use that high pressure fuel that is contained in the rail to create a spray pattern,meter and inject that fuel into a particular cylinder for injection.

 

all the fuel pressure is contained in the RAIL which is a fancy way of saying manifold.

 

not unlike a gasoline engine with multi port injection but at much higher pressures.

 

last of the 6.5's had a ( stanadyne I believe) electronically controlled distributor type pump which does exactly what it says, it distribute metered fuel individually to each of the cylinders in firing order.

 

Older 6.2's and 6.5's had a mechanical distributor type pump.

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yea i hate working on them, or when someone brings in a 80's somedthing 5.7L or 4.3L. i just wanna take it outback get out the .45 and put it down, and say it has a cracked block or something.

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common rail fuel injection uses a high pressure pump to create the pressure for injection and the injectors are simply electronically controlled sprayers that use that high pressure fuel that is contained in the rail to create a spray pattern,meter and inject that fuel into a particular cylinder for injection.

 

all the fuel pressure is contained in the RAIL which is a fancy way of saying manifold.

 

not unlike a gasoline engine with multi port injection but at much higher pressures.

 

 

Is there an echo in here?

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common rail fuel injection uses a high pressure pump to create the pressure for injection and the injectors are simply electronically controlled sprayers that use that high pressure fuel that is contained in the rail to create a spray pattern,meter and inject that fuel into a particular cylinder for injection.

 

all the fuel pressure is contained in the RAIL which is a fancy way of saying manifold.

 

not unlike a gasoline engine with multi port injection but at much higher pressures.

 

 

Is there an echo in here?

 

 

 

 

 

 

Probably ,seeing as you posted a link and I didn't bother to open it.

 

I'm guessing that whatever was on the link you posted said the same thing as I did, but with more verbage.

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I didnt post a link, way back on January 7th I answered the question. Scroll up a bit.

 

 

 

 

 

June 7th.

 

was too long for me to read all of it.. sheer laziness on my part. you may call my post a summary. I offer my humblest apologies.

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