Pump Uncertainty

[Hit.It]

Hello everyone!

1st post here... a question.


I'm barely getting started into diesels, and this forum and its posts have been very instructional (plus google).

I bought a bunch of diesel mags yesterday, and already read through them...
I'm having some questions regarding the pumps.

There's the supply/tank/lift pump that does low pressures, up to 75ish psi... right?
Like the FASS, the AirDog... right?

Then, if I'm not mistaken, comes the "injection pump" where things get interesting at 3,000 to 5,000 psi.
Injection pumps are "the P-Pump" (P7100), and the CP3.

I've seen some rigs (in the magazines) with dual CP3 pumps.
That's where I'm lost.

They run 3,000 psi from TWO pumps into one injector?
Is it a "Y" for each injector line?
Are there little green men down there that decide where to send the metered dino-juice?

Sorry,... yet I must be missing something.

Again... thanks for all the input... I just lack any hands-on (or even eyes-on) experience.

Thanks to every one!

-- AJ
.

PS: First diesel to be a

[Hit.It]

Ok, after some reading... I think I got it.

The P7100 style pumps both increase the pressure (over 3,000 psi), and ALSO pump individually into each injector.

While the CP3 style pumps (and the VP4??), what they do is increase the pressure into the fuel rail... from there, the injectors open on their own (from computer signal).


Right? Wrong?
Go home already? :p

As an aside, I was reading an article in Diesel Power about the Duramax engines.
It states that;

the electrical power required for fuel injector operation is 93 volts DC. As much as 20 amps of current is required to open a fuel injector, while 12 to 15 amps are needed to hold the injector open against fuel pressure.

So... if my math is right, that's
(93v) x (20A) = 1,860Watts

The injector pulls (momentarily) 1,800 WATTS?!?!?!!!

Sweet mother of jesus...

I guess real trucks don't need spark plugs after all...

[smitty16s]

Welcome to the .org im sure alot of people here will be able to help you. Its great here.

[dhanna6powerstroke]

Subscribing for learning purposes!

[BigIslandBoy]

Here's a bump for ya. I'm interested in learning too.

[mschn99]

Your posts are referring to Dmax and Cummins motors.....they have entierly different pump systems.

Not knowing which motor you have, i will go over all three...

On a 94.5-2007 motor (7.3's and 6.0's) they are all the same basic system. There are some minor differences in the way the injectors function and the operating range of the high pressure oil system..but i will generalize it.

94.5-97 pickups use a mechanical (camshaft driven) fuel pump mounted in the valley of the motor to bring the fuel out of the tank and send it through the fuel bowl and to the inectors. 99-07 trucks use an electric fuel pump mounted on the framerail right about at the drivers door area. Either one uses the fuel pump to get the fuel to the injectors at anywere from 45-55 PSI in stock form...... From there the fuel has to be injected into the cylenders out of the injector.

This system actually uses oil to push the fuel into the cylender. The standard oil pump (the one similar to the one any motor has) pushes the oil through the motor and also into the high pressure oil resevour. From there the oil enters the high pressure oil pump and is sent through the system at pressures from 500PSI at idle to over 4000PSI on some 6.0's (peak pressure varies by year and motor). the oil in the injector at great pressure pushes the fuel out at 6 times the amount of pressure its at through an intensifier piston in the injector (1000PSI of oil pressure means the fuel is injected at 6000 PSI)

There are a few different stock and aftermarket forms of these pumps for the 7.3. Ive heard rumors of pumps for 6.0's but i havnt seen one yet myself.....i also havnt reasearched to see if they are out yet. Terminator, Stealth, and Dieselsite are the three biggest manufacturers of aftermarket pump setups. Some are single pumps that can put out more volume and pressure, some are twin pumps with two pumps stacked back to back.


The 6.4 is very similar in operation, but does not use oil. Its a Common Rail system, which still uses a pressurized fluid on one side of the injector to pressurize the fuel entering the cylender, but in this system there is two Fuel systems instead of two oil systems. The oil enteres the high pressure fuel system at pressures that can approach 30,000 PSI and then the fuel in the injector is injected at a 1:1 ratio at the same pressure.....so there is no intensifier piston and the system is simpler and quieter......

[SCUFFY828]

looks like marc has this one covered , only thing i will add, is the cam sensor also sends a input back to the pcm in order for the pcm to send a signal to the idm to tell which injector to fire at what time, in which thats when the oil and the fuel is doing its job inside the injector as marc described earlier , so its a really complex system that has alot of inputs with the fuel , the oil and the electronics used to fire the injectors , not counting the oil and fuel pumps needed to makes this all happen, what is really amazing is the milliseconds that all this happens

[Patrick]

I just want to say "Whats up Marc"? Good post guys.

[6.0 p-stroke]

I guess I learn somethin new every day.

[mschn99]

Originally Posted by Patrick

I just want to say "Whats up Marc"? Good post guys.

Same ol Chit dude.....workin too hard....and tryin to have fun!!! Life is good!!! How bout you???