my airdog 150 used to make this louder kinda annoying noise and i grew used to it and it was normal and i always had about 15psi. since the weather has dropped below freezing hear in ohio my air dog only makes that noise for a few seconds when i kick it on and then it get quieter now... also i noticed that my psi drops to like 12 randomly just cruising and when idling and if i blip the throttle it will actually go back up to 15-16 psi and then will soon drift back to 12ish.... i bought a new filter and water separator but haven't swapped them yet... just wondering if anyone has any ideas... this truck has also had a previous issue of if you lift your foot of the gas to quick it sometimes stalls and needs the injector lines bled. i learned to live with that for the time being and have been told it is somewhat normal for a vp44 truck with as much done to it as mine.

any help or input would be appreciated, thanks.

 

Video of the gauge(bottom)

Airdog issue:

 

Do you add any anti gel to your fuel? If you have straight #2 diesel with no treatment it's possible your fuel is thickening up some. That would explain the noise change as well as pressure.

Untreated #2 diesel usually gels around 18 degrees.

 

Im currently un gelled... its goten to be 20 degrees in the AM around here lately so i bet its thickening over night.. but it weird behavior... with it randomly regaining normal pressure or when i stab the gas it regains...

 

Currently un treated fuel i mean