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.

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.

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.

Ben

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.

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.

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.

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.

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.

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.

you know why they dump fuel back to the tank on a diesel engine?

fuel the injectors dont use....? There sprobably some other huge long complicated answer that I have no idea of.

to heat it up too. The fuel returns to the tank at around 140 degrees on a Dmax when the engine is up to temp. There is a fuel cooler tho to bring it down a bit.

some injectors also return more fuel than others due to many reasoms, hence the "balance rates" readings

three main reasons to return fuel , or run excess fuel thru the injectors.

helps clean em

de-aereates the fuel

and cools the injectors.

they really dont want to heat the fuel but it is a byproduct of running the fuel thru the injectors. it seems that once diesel fuel reaches about 125 degrees or so, it has the same effect as lowering the cetane rating of the fuel and for every so many degrees of fuel temp above that point you lose a certain amount of cetane
rating of the fuel.

so, why do they have fuel heaters?

heh nothing worse then messing with one with a screwd up fuel heater spen two days chaseing that problem. not as much as the magnatized crank problem but close to it.

cold weather operation

duh i forgot about cooling the EDU, another reason. It generates heat in transforming the voltage and firing the injectors. There is no fuel heater on a duramax. Fuel gets hot enough running thru the EDU Didnt know that happens to diesel above 125*. Dmax fuel temp can run up to 140* or so. So is the cetane rating effectively lowered by that? Then again, thats the temp of the return fuel.

Dmax, if I could find it somewhere in my papers, there is a cetane derating chart for fuel temp.

if I remember correctly it its omething like the cetane rating goes down by 1/2 a point for every 10 degrees above 130 degrees/

not much of a factor yet.

ahhh ok thanks, thats interesting info tho.

I dont know how hot other diesels return fuel, whether its more than that (130) or not. I would assume HPCR diesels return fuel hotter simply because of the pressures involved??

a dmax will pull back rail pressure to 110 MPa (dunno what that converts to in PSI, I think maybe around 17,000?) when fuel temp exceeds 230 degrees, and down to 70 MPa when fuel temp gets above 235*. I cant ever see it getting that hot tho. I think the hottest ive seen it is maybe 140 degrees???

ben

most of the heat is from flowing thu the injectors, since they are in the head they warm the fuel.

all diesels get the fuel warm.

I'm at a loss to what you mean by MPa.

I've heard of Kpa, which is also Kilopascals, a unit of pressure and I believe 100 Kpa equals one bar. one bar is 14.7 psi or approximately 30 in Hg.

return side doesn't have much pressure, whatever the unit of measurement may be.

MPa = Milipascals. Next measurment/step up from KPa. You have to measure an HPCR fuel injection system in MPa because the huge pressures involved. Stock, a duramax (and 03+ cummins) runs 160MPa rail pressure, which is roughly equal to 23,200 psi. The dmax and cummins use a nearly identical fuel injection system. The CP3's are identical as well, except the CP3 used on the Cummins has the high pressure lines routed differently.

although on a Bosch HPCR/CP3 injection system, the EDU is what mainly heats up the fuel. Driving the 48volt / 96volt injectors creates a huge amount of heat, which is why fuel constantly runs through it. Not very much fuel is actually returned to the tank on an HPCR engine because the engine really only sucks from the tank what it actually needs. The fuel pressure regulator returns "some" fuel at idle and lower rail pressures, but the injectors use "almost" all of the fuel that is fed to them because rail pressure coincides with the amount of pulse width commanded.

M means Mega in metric, or 1 million. k is 1000 as in kilograms or kilometers which is 1000 times any unit of measurement so it would seem Megapascals are in millions of pascals.

so it would seem 160 Mpascals would be 160000 kpa or "alot" in laymans terms. I think we got something off by a few digits here but thats another story.

figure 100 kpa equals 14.7 psi so 1 Mpa must equal 14,700 psi, 2Mpa would be about 29400 psi so I'm thinking we got a error in our numbers here but were both on the same page as far as thinking about it.

sure it isn't a lowercase m? which would be milli's or one-onthousandths of a kpa?

they got to run the fuel behind the ECMs on several different brands of engine as a way of cooling the ECM, as you said it creates alot of heat, which is absorbed and removed by the fuel which is used to cool the ECM.

Detroit has gotten away from it lately and Cummins followed suit.

http://www.ilpi.com/msds/ref/pressureunits.html

psst kick check your math 14.7 x 10=147 100kpa x 10= 1000kpa/1Mpa. 147psi is 1Mpa (losely 1.01353Mpa for the nerds)

GPa i heard of, and Pa i heard of, but never mPa. m is really small 1psi is like 6,894.7625831 Pa in mPa that would be 6,894,762.5831 just per 1psi

your right Onyx!!!!!!!!!!!!!!!!

I knew something didn't look right,I shoulda looked in the mirror and I woulda saw the problem..

It is MPa. Whether it stands for milipascals or megapascals im not sure, I was almost positive its milipascals. I am 100% sure it is MPa. Look at Engine Data 1 or 2 on a Tech 2 and press the 'units' softkey. Switches from PSI to MPa. ~30MPa is idle. 160MPa is max commandable rail pressure (on a stock engine).

Not to split hairs...but the ECM and EDU are two completely different things.

what does the EDU do?

drives the selonids in the injectors. electronic driver unit.

simple explanation here http://www.duramaxdiesel.com/12_media/index.htm

in the interactive section has moving animation and everything. not super techincal or anything.

engine drive unit, basically a relay switching station for the injectors. Injectors on an LB7 operate at 96volts, LLY injectors 48volts. The ECM obviously cant drive them directly, so teh EDU controls them for the ECM. The EDU is directly slaved to the ECM. It talks to it with dedicated "injector control wires" as well as on the J1939/CAN bus. Makes a lot of heat from transforming/regulating voltage as well as switching injectors, so fuel runs thru it to keep it cool.

The injectors actually are switched with their ground. They have constant "positive" power going to them all the time. Ground is switched on and off by the EDU. Each bank of cylinders is on its own separate 48/96 volt EDU-driven electrical bus. That way, if there is a short in the "+" power wires going to either bank, the EDU will detect that short and shut down that bank and set the corresponding DTC to prevent damage to teh EDU, electrical system, or injectors. It cant isolate the single offending injector because remember all of the injectors on each side are fed off the same common 48/96 volt bus. So if theres a short "anywhere" on the left or right bank, it brings down the whole side. Kinda sucks it cant isolate the one injector thats shorted and just shut IT down, cause the engine runs like crap with only one bank firing. Also you have to diagnose the whole bank as a whole, so it takes longer to track down wiring shorts. I dont know why they used a "reverse DC" wiring setup. Something with load switching, its less stress to switch a ground on and off, I dont know, Im not an electrical engineer.

Also known as a FICM, fuel injection control module

hmm interesting website...I think I first saw it years ago when the dmax first came out but havent looked at it since...I dont think theyve updated it in a while...

it IS wrong on one thing. It says the fuel is fed thru the EDU by a low pressure pump. There is NO low pressure/electric fuel pump on a duramax. Everyone thinks there is a lift pump or something but theres not. The CP3 has two sides, a low side and high side, two little reciprocating pistons, one larger displacment than the other. The Low side sucks fuel [alllll the way] from the tank and pressurizes it to around ~300 psi. Then this is discharged to the high pressure side of the CP3, which compounds that pressure to X psi, dependant on engine RPM. It is driven 1:1 off the cam gear, which is driven directly off the crankshaft. Water pump is also gear driven off the crank. There is no timing chain or belt; all gears. Theres an ECM-controlled pressure regulator on the back of the CP3. Depending on what rail pressure the ECM is commanding, it supplies the regulator vlave with various amounts of current to either allow no bypass at full throttle/max rail psi (0 mA) or almost full bypass (~1500 mA) at idle, which is around 4600psi rail pressure. I think it needs around ~3000 psi of rail pressure to even start/run.....something like that...

yeah, and it says "center mounted turbocharger for easy serviceability" Uh-huh ok...Anyone who can R&R a duramax turbo in less than 8 hours is a hero in my book...its a huge PIA.

[
OKee dokee, the EDU is a slave unit that controls the injectors, and is dependent on the ECU to tell it what to do.

not unlike what Cummins was using until they came out with the current CM875 system.

and they all get hot.


the big boys have gotten away from fuel to cool the Eelctronics, might be because they dont have the tight underhood areas to deal with like the D'max or some improvements in the hardware?.

yep exactly, just a slaved injector control.

EDU's rarely fail, only potential problem is if it gets an internal fuel leak and fills up with fuel. The LBZ duramax did away with the EDU altogether tho. On the LBZ the injecotrs are driven directly by the new smarty-pants Bosch A35 32bit ECM.

EDU's rarely fail, only potential problem is if it gets an internal fuel leak and fills up with fuel. The LBZ duramax did away with the EDU altogether tho. On the LBZ the injecotrs are driven directly by the new smarty-pants Bosch A35 32bit ECM.

[/quote]


the other guys had the ECM mounted on a plate that the fuel flowed thru, wasn't anyway for the fuel to get in the ECM.

ah ok so it was like a separate heat sink type deal that was 'thermally bonded' to the ECM?

Ive only heard of two or three EDU's fail and cause fuel to leak into the insides of them, but theres potential for it becaus the fuel actually runs thru it.

anyway i was sitting in the shop after work turning some screws on the dirt car with i hear this awful racket. i turned around and see this brown nice looking olds pulling in i was think woo that sounds like some $$. then it hit me thats 350 disel sound... joe called me up later and said "d**n i didn't think you could move that fast i heard the back door slam befor the wrench hit the ground."

LOL!!!

hahahahahhahahaha

never actually heard one...but heard OF them

do they sound like 6.2's at all?

yea, nock ping clank clock clock ding pong, make you think it's gonna explode at any moment rods flying out of the block and everything.

but inside their nicer lotta felt (mouse bedding) in the firewall(bulkhead) and hood

not as bad as i make them out to be replace alot of distrubiters(fuel not spark) and glowplugs on them.

once had this fella diy the distributer it is fairly easy. only he redid all the fuel lines made them just long enough to hook to the injectors.

took about 2 days to get all the lines the same lenght and bent correctly to fit back on the distributer and injectors. so they would all be timed the same.

what Detroit and Cummins were doing was an actual plate that was bolted to the engine block and fuel ran thru the inside of that plate.

the ECM was mounted on that plate.

if you needed to do something to the ECM you unbolted it from cooling plate

you wanna hear something noisy??

Old 2 strke Detroit running with a broken crankshaft.

woo i bet that was a racket.

yeah, it was.

a deaf man coulda heard it, funny to see the crankshaft moving in and out on the front of the engine.

seen a 8V 71 detroit running with a broken piston, had busted the top of the piston and forged the piston crown into a metal lump that was bouncing around the combustion chamber, beat the hell outta the head too. engine actually ran pretty good, just had a noise. LOL.

they don't make em like that anymore.

yea most of the 71's got regulated to marine use.

dad has 71's as generators on the barge forget the designation but the I6

now the GE main engines are awsome. it's got i wanna say capulized heads basicly one head for each cylinder. something breaks they have like 4 spare heads just unbolt rnr the head and fire it back up. even has a access panel in the pan unbolt the rod pull the sleeve rnr and your up and running in under 2 hours. just unreal. but out there time is serious money.

6-71.

yea, i wanted to say that, but i didn't wanna be wrong

71's were available in many variations.

2,3,4,6,V6,V8,V12,V16 and V32 come to mind.

LH and Rh rotation

starter and oil cooler avaialble on either side of block, depending on application.

2 valve and 4 valve heads

all were supercharged, turbos as an option.