Diesel Theory

[Matt400]

Wowa!:--) 25,000 is a bunch. I see fellas are monitoring fuel pressure with add on gauges. What particular circuit out of the 3 are they watching and why?



Now I understand why a simple electric pump wont do.

 

[A Johnson]

They are monitoring the low pressure (15PSI side) to catch a faulty transfer pump before it fails. When they would fail on the pre 03 24 valve engines, the resulting restriction in the system would be detrimental to the VP-44.



I dont know how much damage a failed transfer pump would cause on an 03 product but I think it would be less of a problem, due to the gear pump (150PSI) looks like a much more robust deal,... ... . In my opinion. This is just my theory, time will tell.



A Johnson

 

[Matt400]

Originally posted by A Johnson

the resulting restriction in the system would be detrimental to the VP-44.

I read somewhere that it is very possible to have the low pressure pump fail and the driver be un aware, no change in performance yet soon to be failure of the VP-44.

Is the VP-44 pump the 150 psi pump? Are 03 owners still going to install FP gages for the same reason or are they needed?



Gas engine in-tank pumps are capable of 150 psi I believe when run unregulated, seems one of those could replace the two primary pumps on the Diesels.

 

[A Johnson]

The VP-44 is on the 98. 5-2002 trucks.



I can't remember off the top of my head what your fuel pump is called, name wise.



I think most wise 03 owners will install a fuel pressure gauge, it will advise you if there is a problem in the low pressure fuel cuircut due to a dirty fuel filter or some other malfunction.



I would prefer to have the 150PSi gear pump that Bosch has provided in the system, and try to determine if I really needed the 15psi transfer pump, as I mentioned in my first post. If the gasoline pump will provide 150 unregulated, then I would want something that is not allways working close to max capacity.



However an in tank pump might be an option for a 98. 5-2002 rig if it could be regulated down to 15-20 PSI, and adapted to the pulse width signal from the ECM to provide for less than 5 PSI during the crank cycle.



Keep in mind I don't own one of these, I did have some training at work on the ISBE (technical name for your engine), and have worked a bit on the EGR version of the ISBE. The rest is just my theories. I think it would be unfair to ask people to start experimenting on their rigs, after all it does have a warranty doesn't it? But there are allways some who want to improve things.



A Johnson

 

[Matt400]

Originally posted by A Johnson

I think most wise 03 owners will install a fuel pressure gauge, it will advise you if there is a problem in the low pressure fuel cuircut due to a dirty fuel filter or some other malfunction.

I think that may be good advise, in the gas sector if a pressure problem developes the driver knows something is up. I will need to study up some more on the 3 phases of pressure more to evaluate it.

If the gasoline pump will provide 150 unregulated, then I would want something that is not allways working close to max capacity.

They run maxed out all the time, the regulator is on the fuel rail so the in-tank pump is working at the same speed all the time.

An in tank pump might be an option for a 98. 5-2002 rig if it could be regulated down to 15-20 PSI, and adapted to the pulse width signal from the ECM to provide for less than 5 PSI during the crank cycle.

That's an idea... or a High Performance frame mounted pump outside the tank wired to receive full 12V in the key on position and a reduced voltage in the "crank" position that would lower pump pressure.

ISBE (technical name for your engine), and have worked a bit on the EGR version of the ISBE.

I thought EGR was still in development, are they on the road already? I don't think my CA model is EGR.

What does ISBE stand for?

 

[Blakers]

Originally posted by A Johnson

For years Cummins just used a gear pump to pull fuel from the tank and supply the injectors with pressure on the PT system, it worked very well but you need to run at least a 1/2" supply line and sometimes when they ran out of fuel it took a bit to start them, also the PT system was a lot more tolerant about starting with some air in the system.



A Johnson

What is the PT system? Is that the system Cummins uses where each injector is actually its own pump and is driven by a pushrod off the camshaft? Like a Detroit?



Blake

 

[A Johnson]

Matt, ISBE stands for Integrated (Or Interact , depending on who's passing out the answers that day)Systems B series and I'm not sure if e stands for egr, or Echo which was the code name for the development engine that had egr. There are some differences between your engine and the one I worked on. As I stated before it had egr, it also had a rear gear train. The low pressure fuel transfer pump is slightly different than the ones I've seen on the Dodge.



Blakers, the PT stood for pressure timed. The fuel was metered by the injector and the injector was actuated by the camshaft. Metering amounts depended on fuel rail pressure at a given rpm. Typical rail pressures ran from @ 7 psi at idle to 180 @ 2100 rpm for a 250 to 400HP engine depending on the flow of the injectors. I hope you don't need more info because its a hard system for me to put into words for an accurate description.



A Johnson

 

[dmurdock]

The way I understand it the lift pump isn't really important except in case of lost prime. The last TDR issue said that cummins sell's these engines in different configurations (generator i think) that don't even use lift pumps.

 

[Matt400]

Originally posted by dmurdock

The last TDR issue said that cummins sell's these engines in different configurations (generator i think)

On that note does anybody know all the different applications that the 5. 9 is found in?

 

[Blakers]

Originally posted by dmurdock

The way I understand it the lift pump isn't really important except in case of lost prime. The last TDR issue said that cummins sell's these engines in different configurations (generator i think) that don't even use lift pumps.

I bet those engines have gravity feed with the fuel tank above the engine - no lift pump would be needed.

 

[A Johnson]

where to find a 5.9

Dodge, Freightliner, marine, generator, road graders, berry pickers, silage baggers,firepumps, motorhomes, Peterbuilt,Kenworth, loaders, Case crawlers and backhoes, Ford, various industrial pumps and powerpacks, and almost anything that needs 120- 300 or so horespower in a small package.



A Johnson

 

[Blakers]

Originally posted by A Johnson

Blakers, the PT stood for pressure timed. The fuel was metered by the injector and the injector was actuated by the camshaft. Metering amounts depended on fuel rail pressure at a given rpm. Typical rail pressures ran from @ 7 psi at idle to 180 @ 2100 rpm for a 250 to 400HP engine depending on the flow of the injectors. I hope you don't need more info because its a hard system for me to put into words for an accurate description.



A Johnson

Thanks for the explaination. I'm not sure if that's the system I was asking about or not.



I know some of the Cummins have injectors just like Detroits that run off the camshaft where each injector is its own pump - all in one. Low pressure fuel is fed to the injectors, then the cam pushes the injector plunger in, creating high pressure fuel, which sprays into the cylinder through a nozzel.



Blake

 

[A Johnson]

I saw a Detroit injector once, about 15 years ago I rebuilt it in college, that is my only Detroit experience so I cannot speak for them at all. I believe the Detroit injector is a closed nozzle design, whereby the fuel pressure increases from camshaft actuation until pressure overcomes the bias spring and starts squirting in the cylinder. The PT system has an open nozzle design where fuel actually can drip in the cylinder with the engine shutoff, the injector uses a cone shaped plunger to force the fuel in the cylinder to overcome cylinder pressure when the engine is running.



All B and C series Cummins use a closed nozzle, Celect(N14/M11) are closed nozzle, NT series engines were all open nozzle and Signature/ISK/QSK are open nozzle.



The PT system's fuel pump was a variable pressure pump that controlled the pressure/volume of fuel sent to the injectors, the Detroit controled this with the "rack" on each injector I believe.



A Johnson

 

[Big_Daddy_T]

I was just at cummins nw and they had a rack sitting on the counter. I looked at it and decided the injector would need to be run off the cam. No way can those fuel lines hold enough pressure to be a closed injector(pop off) system like the isb. It looked like maybe it would hold maybe 40 psi. Im suprised to hear it holds more. It was a little rough around the edges. One of the guys working there owns a 4 banger pt. Was pretty proud of it. Said it was probably older than me. The rack on the counter was for a 6. He said it was the predecessor to my engine. He knew quite a bit about pts.

 

[Speedo]

Detroit unit injectors

The rack on the Detroit unit injectors is used to control the

amount of fuel that went into the injector, the timing was

controlled by the height setting and an internal plunger that was

actuated by a rocker arm/ push rod/ camshaft that created the

pressure. Fuel was supplied by a pump driven off of the blower

and max pressure for most Detroits was somewhere in the 70

psi neighborhood. The newer 4-strokes (50 & 60 series) still

create pressure with an internal plunger but because of the

higher pressures required for emissions and the fact that these

engines are overhead cam the cam followers for the injectors are

ceramic. Fuel supply is no longer controlled by a mechanical rack

it is now controlled by solenoids that are signaled from the ECM.



Gus