It doesn't affect fuel mileage, that I've noticed, whatsoever, positive or negative.

All it does is make sure that the VP44 or CP3 actually get the fuel it needs.

The VP44 and the CP3 differ significantly in therer operation, but the FASS and AirDog supply them with the volume that the CP3 needs and the pressure that the VP44 needs.

The VP44 is very sensitive to pressure drops and anything under 4-7 psi is where it starts getting dangerous for the VP44. You lose the pressure and you lose the lubrication.

The CP3 is muh less sensitive to pressure, it just needs the volume. The CP3's in the Chevy trucks don't even have a lift pump supplying what is essentially the same Bosch injection pump and injectors. The CP3 makes it's own pressure for lubrication based on the position of the FCA, which routes the fuel to the rail and to the lube system.

The engine is only going to use what it needs / requests, the FASS or AirDog just make sure it gets the adequate supply.

 

Coal Train,

(assuming I'm not violating forum policy by asking this) can you recommend a reputable place to purchase these parts from?

Also, I am a newbie to this so please bear with me as I expose my ignorance.... my question is: When replacing the fuel injection pump, does the high pressure side of the fuel lines need to be tested or just the low side? I ask, because I can't seem to find a fuel pressure tester that goes higher than 100 psi. or would I have to take it into a shop for testing after installation?

 

Well, there are a few folks that I like dealing with.

1 - David at Diesel Manor
2 - Gus at FarmBoys Diesel
3 - Robin at Geno's
4 - James at Rollin Smoke Diesel
5 - Tyler at Meyer Perfomance and Fabrication

For the FASS or AirDog, I say deal with David. I've yet to have a bad experience with him.

IF you have to replace the VP44, give Gus a call. He's a great guy, again I've had no issues with him and his pricing is great.

Ya can't go wrong with Geno's and either Tyler or James will get ya taken care of as well.

You can't test the VP44 with a regular FP test gauge. It pushes fuel pressure at up to 14000 psi. Easiest way to check is crack the #1 injector line and check for fuel spray. Be EXTREMELY careful doing this. At idle, it's pushing 4000 - 6000 psi. Use a piece of cardboard over the cracked line to check for fuel spray.

I would start by replacing the lit pump and see if this solves your problem. It's much cheaper than the $1000 - $1500 that a new VP44 is gonna cost ya.

 

If there is no pump on the block it has probably been retrofitted to a in tank unit.
You can't get the stock style lift pump from Chrysler anymore they only sell the in tank retrofit kit for 98-2004 models.

This is what the stock lift pump looks like.
It should be by the fuel filter canister if it hasn't been retrofitted.

 

This is what a retrofit kit looks like.
That big alum block takes the place of the block mounted pump.

 

Thanks for the post rabbler.

The picture of the retrofit makes it clear that my truck is already retrofited. Where the lift pump should be in my truck, that alum block shown in the picture is there instead.

The drain valve on the water separator is also defective, so I've decided to replace the lift pump and water separator with the airdog system.

 

Do you have to remove the in tank pump to install the airdog?

 

Ok, I finally got a fuel pressure gauge and tested the lines.

I hope what I'm writing here makes sense to everyone:

At the fuel pressure test port off the water fuel separator it runs at approx 10 psi the first two seconds with key on, then drops to nothing. Then with Engine cranking goes back up to approx 10 psi and remains steady.

Next the pressure test port at fuel injector pump the pressure goes up to approx 10 psi with engine running and remains steady.

These pressures are different than what I understand that they should be but not so sure what to make of it.

good pump.... bad pump.... which pump to dump....

 

The in tank pumps are high volume low pressure pumps.
They are about 1/2 the pressure of the original Carter block mounted pumps.
Test for volume not pressure on these pumps.
disconnect the hose to the inlet of the injector pump.
Run the pump for 10 seconds and you should get at least 570 ml of fuel.
test 3 times and take the average. If flow is low change fuel filter and retest.
If still too low you probably need a new lift pump.

 

Hy Guys


I`m far far away from you, i`m from Europe.
I have recently buy a DODGE RAM 3500 with 5,9 cummins diesel motor.
It has 5 years, and 120.000 miles.

I have now a problem with my car and don`t have any ideea where to look.
My engine stops during driving. It has not to do with RPM of motor, i can be at 1500 or 3000 it will also stops some time.
Also the conditions that this happens is not clear. Some times 3 time in a day, some times just once every day, not depending on road condition, speed or distance of drive.

Can you help me out with some indication what can cause this?

Also after the stop, the engine will go on on next key.

Please help