Engine/Transmission (1998.5 - 2002) grid heater and air dog not working

[cmills]

Anyone know what would cause my grid heaters and Air Dog fuel pump not to come on when the key is turned to the on position to let the grid heaters cycle? The pump comes on and runs for a couple of seconds if I bump the starter and I know it is working when the truck starts because it has fuel pressure.

 

[CM_Guest]

If it kicks in momentarily when the starter engages, it sounds like a bad connection somewhere that "makes and breaks" as the engine is cranking. I'd check every power connection you can find under the hood, make sure the battery cables (positive and ground) ends are solid, check the ground cable connection to the block, etc. I don't have an electrical circuit diagram in front of me and I don't know how your AirDog is powered. But I'd trace the wiring back from the pump to wherever it's connected and begin my diagnosis there. It's probably operated off of a relay. Check every ground you can find as well.

 

[SnoKing]

Anyone know what would cause my grid heaters and Air Dog fuel pump not to come on when the key is turned to the on position to let the grid heaters cycle? The pump comes on and runs for a couple of seconds if I bump the starter and I know it is working when the truck starts because it has fuel pressure.

That is the correct operation. Turning the key on lift pump runs a couple three seconds. Bump the starter and it runs 27-30 seconds. Bumping is how you refill the filter and lines have servicing the filter. I bump it enough times to get the fuel pressure to slowly peter out(fully primed) or the air is not all out of the system and you will loose prime. If you loose prime then you have to start crack injector lines. When I got rid of the OEM Carter pump I had a lot less problems changing filters.

Grid heaters are control by air temps. I have to check mine out as I think maybe one is not working. If I have the exhaust brake on in warm up and put it in reverse to back out of the garage the motor lugs down. Started doing this last winter and it finally dawned on me that it may be a grid heater issue. My boat uses the same Cummins relays in the start circuit and they are known to have issues as they age. I steal spares back and forth from time to time.

Chris