I installed a AirDog fp100 and went from 7 psi at idle stock to 20 psi at idle now...The truck used to start at just a bump of the starter, now I have to crank it over for 5-6 seconds and sometimes it will start to fire but not keep going and takes 2 or 3 tries before it keeps going...

I bled the system at the injection pump inlet when I installed it and it fired up.. I have been driving it for a few days and its not any better, can air stay in the system even after many wide open runs..?? Or is it just the higher psi making it hard to start..??

Thanks

 

I'm thinking you have a fuel leak somewhere. Any loss in fuel mileage?

 

The fuel/air leak would be the most likely issue. Check all the fittings close to see if they are wet.

Also be sure to fill out your signature so we can see everything you have on the truck. Sometimes it can make a big difference in what the problems might be.

 

Ya, I filled out my sig right after posting and I thought it would put it in there, I guess not..

I am showing 20 psi about a foot before the injection pump, and I havent noticed any leaks... the only fitting that bothers me is the push on for the suction tube in the tank...factory style push on style. I was worried maybe that could draw air, but I figured the AirDog would get rid of it anyway....

 

Quote from FASS

Hard Starts
Usually the FASS only encounters hard starts on the 1998.5 – 2002 Dodge Cummins with the VP44 injection pump. If this occurs it is usually on a VP44 with high mileage, and/or a VP44 that has been subjected to around 5psi of fuel pressure or less. It is more likely to occur when the weather is warmer/hot.

Explanation of Diaphragm: The diaphragm in the VP44 is designed to move about .5mm with proper fuel pressure(about 7psi min.). When the VP44 is subject to about 5psi or less the diaphragm can move up to 2mm, an increase in movement of 4 times more than what it was designed to move. With this type of movement the diaphragm will eventually develop stress cracks thru out the body of the diaphragm. One job of this diaphragm is to separate low fuel pressure and high fuel pressure in the housing of the VP44, when the cracks are present this separation does not occur. This will lead to hard starts even with a stock OEM lift pump!!


It may be time for a new VP44

 

Very good info. Looks like thats the answer to the issue.

 

That's what I was hopin to not have to tell him about. I was hopi it was just a lose fitting someplace.

 

Edge Juice w/Attitude and you had 7 PSI at idle how much @ WOT ?

 

i just got the truck...it was stock i put the edge on it and it would drop to 0 on WOT so I only did that once and out it back on level 0 untill I got the AirDog installed... at $1000 for a new pump I will have to just live with the hard starts.... that sucks.

I dont suppose anyone sells the parts for the VP44 ?? I have always heard they dont...

 

The VP is a sealed unit that can only be repaired by an authorized dealer. But it may be worth talkin to one of them to see if there is something thaht can be done with it. I would also suggest changing the Banjo bolt on the outgoing ful side of the VP44. This bolt has a spring loaded pressure regulator built into it that mainains the internal pressure to the VP and it frequently goes bad and causes a wide assortment of problems. It's not expensive and you may get lucky.