nathan04

My Vp44 on my '01 is about to bite the dust. I have an H.O. pump now, but I'm thinking of trying a S.O. pump. Whats the advantages of the S.O.? Also where is the best place to find one cheap? Thanks

KATOOM

Some vendors only sell one style of pump, the SO. The SO pump runs at a higher volume than the HO pump which runs at a higher pressure. You can put an SO pump on an HO but you cant put an HO pump on an SO. Not that you'd want to, and the ECM wont allow it for some reason.

BigGreen

Will the VP44 go out with out codes? How do you check it?

DIESELWRKS

Yes and No on the codes. clear as Mud right.

read this good info.

http://www.bluechipdiesel.com/vp44diagnostichelp.html

BigGreen

Ok I tested the connector and have power where it says and not where is say not so that's good. I have pressure from lift pump. I cracked the line at the head and has some pressure but not very strong. From what I am reading the VP44 should be pouring the fuel out if it is good so I think it is dead. I did get another code 1689 but after cracking the lines so means nothing.

DIESELWRKS

before this code what were the others if any. also what symptoms are you dealing with. or is it plain ol wont start?

KATOOM

Whats your truck doing? Why do you think the VP is failing?

BigGreen

**** thing wont start was real hard starting like 5 min of cranking now wont start at all. Before this only code was the 1693 and 0234 neither mean much. I have a Fass DDRP with 18 psi at idle when it does run and the lift pump when you bump the ignition has 20 psi.

I also read tonight to disconnect the heater grid and spray a small amount off either into the intake and try to start without the go pedal and if it starts and immediately settles down to idle then it is the VP44.

I tested the wiring harness and everything worked like the instructions said it should.

KATOOM

First, when it doesn't want to start, remove the FASS fuse and then try cranking again. If it starts up normal then your FASS is pumping to hard during cranking. If pulling the fuse helps then I'll tell you how to fix it. If that doesn't help then when it wont start, pour water directly on the VP. You'll have to carry around a gallon jug or something for this test, and what you're doing is simply cooling off the VP's computer which might have to many heat soak hot cycles chalked up on it, giving you fits. If it starts after you cool it down with water then there's your problem.

BigGreen

When I crank the truck the Fass stops pumping it goes to 0 until I let off the key and it pumps again back up to 20 psi. I was told this is normal.

KATOOM

What exactly is supposed to happen is:

1) When you turn the key to the ON position, the FASS should prime for about 1-2 seconds then stop.
2) When you turn the key to start and crank the engine, the FASS should pump but at about half pressure. You may or may not notice that though.
3) When the engine starts the FASS should run at full pressure.

Also, usually the time between cranking and starting is so fast that its hard to tell if the fuel pump is even doing anything.

So back to my last questions.....

BigGreen

Well didn't help anything to pull fuses.

KATOOM

I dont mean to seem critical here but how specific you are will only help me help you. By saying that, what do you mean "fuses"? There is only ONE fuse for the FASS. If you pulled that ONE fuse and it didn't start any easier then 1) thats not the problem you're truck has or 2) you pulled the wrong fuse and/or to many fuses and cut power to the entire fuel system which would, of course, stop the truck from starting.

So, again, which fuse did you pull? It should NOT be a factory fuse but the aftermarket fuse that powers the FASS which came with the FASS wiring loom.