Today, we're going to give you a redneck definition of common rail.
This piece of art that you see here that is a hodgepodge of several different components,
of several different platforms of common rail light duty diesels, is a masterpiece that
is going to be a teaching tool for you as we go through this fantastic journey of fuel
injection.
Let's begin.
I found myself, when I say common rail to people, when talking about your platforms
of trucks, if a Dodge customer calls and he's not sure if he's got an O2 or O3, I'll always
say, "Well, is it common rail?"
Sometimes that's where I'll lose them.
So let's go into what is common rail, once you have identified whether you've got a common
rail or not.
So the first thing in the circuit, in the common rail circuit, other than your fuel
tank ... Let's cut all that part out.
You guys are smart enough to know that there's a fuel tank.
It's got fuel in it.
The fuel gets to the CP3 pump, but let's talk about the CP3 pump.
CP3 pump, it is a dumb pump.
It is an injection pump, but is a dumb pump.
Here's what the CP3 does, fuel into the CP3, the CP3 has a metering valve on it called
an FCA or fuel control actuator.
Some people call it an Mprop.
The metering valve on the CP3, it regulates the fuel flow internal to the CP3, which builds
the pressure.
That pressurized and that volume of fuel goes to the rail, common rail.
The rail is the common collection system where the fuel is delivered to the injectors.
The fuel is here and it is going through each individual port at the specified pressure
that is coming out of the CP3, and it is always at the injectors.
The injectors are the business end of this, but we're not to the injectors yet.
The rail itself has a couple of key components.
It has got a fuel pressure sensor, always that is inside of the rail or that is in an
injunction block that is tied to the system itself.
You also have a fuel pressure relief valve or cascade valve, some people call them, that
will allow the overpressure ... If the fuel pressure gets too high, it will allow the
excess fuel to dump off back to the tank.
Then the pressurized fuel is delivered to the injectors.
The injectors receive a signal from the FICUM or for the ECM that create the combustion
event that goes into the cylinders.
The fuel sprays in, all the magic happens.
That's what makes the car go down the road.
The injectors are the brain or are the brains of the operation.
The CP3 is the brawn of the operation.
Now, common rail injection, why is it here?
Common rail injection ... and this is a generalization that we're speaking in, only the big three
light duty platforms.
Common rail injection is here because it is cleaner and it is more efficient.
It works from a couple thousand PSI on start up to upwards of above 20,000 PSI.
A full power regiment that gives you better atomization of the fuel, which is going to
give you a cleaner burn and is going to give you a more efficient vehicle.
You're going to be able to pass all those EPA standards and tiers and all the stuff
that you really don't want to talk about today.
So this hodgepodge of parts, we can go into this.
This is a couple of components from several different trucks.
This is actually a real pressure sensor from a 6.7 Dodge.
It's got an LB7 injector here from the [inaudible 00:03:28], 5.9 rail.
I don't know what the lines are off of.
The CP3 is also off of a 5.9.
This rail that I brought up for another demonstration component is off of an LB7.
You Duramax guys are going to know that your FP, your fuel pressure relief valve is in
the back of the rail.
Some of the rails will have the pressure sensor actually on the Duramax rails.
The Fords are completely different.
Fords from 08 and up is common rail.
All of the components are pretty well the same.
They may look different to you.
Some of the lighter model Fords are Piezo injections, and we may get into that and do
another video, but I just wanted to give you a good overview of what is common rail today.
I'm also going to help you with your acronyms.
When you're speaking to someone in fuel systems or common rail is where you're going to see
a lot of this.
You're going to see this everywhere in fuel.
Fuel, when people are speaking in fuel terminology, you will always see talking in pressure, most
fuel guys will give it to you in bar.
They'll say it's 1800 bar.
One bar equals 14.5 PSI for us rednecks.
Now, you are going to have some of your tuners that are going to display your fuel pressure
at the railing, kPa.
What is kPa?
One kPa, kilopascal, is 0.145 PSI.
So that gives you ammunition to have a good educated conversation with somebody about
fuel, common rail, fuel injection if you so choose to.
So I hope this video was helpful for you guys.
If you've got any questions on common rail or anything else, please give us a call.
Thank you.