Austin Brandt

My airdog lift pump on my 1999 24v Cummins has started making noise the entire time the truck is running. It normally makes a pumping sound when you turn the ignition to "on" and are waiting for the wait to start light to go out. The pump recently started making that same noise now the entire time the truck is running. I haven't found any other forums with this problem. Is there a way to fix this, or is it a sign that my lift pump is going out? Thanks

oliver foster

It is most likely a sign that the lift pump is going out.

AlpineRAM

It could also be a sign of the pump sucking a little bit of air- maybe you should look into the connections from the tank to the pump, or look for air bubbles when you open the fuel drain. ( I usually just connect a long transparent hose to the drain and route it back to the filler neck to check for air bubbles.)

Just my 2c

KATOOM

How old is the pump? Is it an older better Pureflow product or is it a more recent Airdogpureflow product?

Also, the fuel pump is supposed to run the entire time the engine is running. If its not then thats a problem.

The correct fuel pump procedures are:

Key turned to ON - pump runs a 2 second prime cycle.

From ON, bump key to START and quickly back to ON - pump runs a 25 second cycle.

Engine cranking - voltage to pump is alternated to reduce pressure by approximately half value.

Engine running - pump runs continuously.

oliver foster

I have run an Air Dog set up for years on my '01. When they start to sound noisy, like a Chevy electrical fuel pump, they are starting to give up the ghost.
I have 3 pump motors give up the ghost over the years.