Fuel Pressure Guage Going Crazy

[frygap]

Just got my truck out of shop and had a vp44 and airdog 165 and set of guages electric . my question is they installed the fuel pressure guage sender at the vp44 the guage is going from 20 at idle to 0 to 5 at wot to 0 to 20 at crusing. i crawled under truck and the airdog will run awile and then stop pumping while truck is idleing. is that normal for it . any advise would help just dont want to damage my vp44 from no fuel pressure

[dripley]

what is the sender connected to? It needs a needle valve or something to isolate it from the pulses of the VP. Yes the pump should be running constantly while the truck is running. Do you know what they wired it up to?

[frygap]

the sender is connected to where the airdog connects to the vp44 i dont know where they wired the pump to

--- Update to the previous post...

will a snubber work or is it the same as a needle valve

[dripley]

Alot of folks use snubbers with succes. I have a mechanical gauge and the needle valve serves a dual purpose. protects the gauge and if I do have a leak in the cab I can shut it off until I can fix the leak. The valve itself is barely cracked open.

[awoods9520]

No, the airdog should not be cutting out. I would check the wires going to it and make sure all the connections are snug and doesnt have any pinched wires anywhere along the frame.