Fuel pressure fluctuating between 0-12 psi
 

Bought the truck two days ago. 99 24v with 273K. Has Air Dog II lift pump. First day i drove it 100+ miles and it stayed at a consistent 15psi while driving. Today, i noticed it down around 11-12 psi and this evening, it started fluctuating rapidly between 0 and 12 psi. Any ideas on what could be causing my problem?

Sounds like "water hammer". Read this article Mopar1973Man's Dodge Cummins Articles - Fuel Pressure Gauge And Water Hammer Effects Is it a mechanical or electric gauge?

It's a mechanical gauge. I forgot to mention too, the truck idles erratically during this and acts like it wants to cut off until i start rolling again. Once i get up to speed, it holds a consistent 10psi.

filters...

I tried to get a new filter and water separator today but NAPA doesn't stock them so I ordered them and they'll be here Monday. Could the filters cause such a dramatic drop in pressure?

Yes clogged filters can. How much fuel do you have in the tank?

just shy of 1/2 a tank.

If you have a truck stop near you check and see if they carry air dog filters. Some of them do.

Didn't think about that, will do. Thanks! Are the fleetguard filters of the same quality as the Air Dog part?

Fleetguard is good. Not sure if they will fit without slight modification. I know with a Cat filter part of the bracket has to be ground away because the Cats are slightly bigger. The fuel gauge in our trucks are notorious for being inaccurate. I'm empty when my gauge reads 1/4 tank so you might want to fill her up and see how many gallons she takes. Should be a 34 gallon tank.

Might fill the truck up, if it quits acting up they might have the straw in to short, so it acts like its out of fuel but just cant reach it when you gas on it and the fuel goes to the back of the tank

If filling up the tank or new filters doesn't work it could be the overflow valve on the vp44. Here is a link for testing it https://www.dieselbombers.com/98-5-0...formation.html

I just took it up to the truck stop and put about $30 of fuel in it. On the way there, it was reading 1/2 tank and my fuel pressure was dancing around and the truck was bogging.. On the way back after fueling, it read right over 1/2 tank but held a steady 15psi.

It only took $30 to fill it up or you stopped it at 30? At least now you know either your fuel gauge is wrong or like texas goat said the draw straw was cut too short.

I only put $30 in it because I was just experimenting. I will go back and fill it up in the morning. I'm about to crawl up under it and see if I can determine relatively how much is in the tank, which will give me a better idea of whether its the gauge or the draw straw.