Archived 2003 Cummins RAM Grid Heater disabling Fuel Pump (need to disconnect)

[bobinyelm]

2003 Ram 3500 HO

I am far from home in the Pacific Northwest with a problem and need to disable the grid heaters as when they come on the disable my external lift pump (the truck will run if the heaters are off w/ a warm truck). It is cold and raining 24/7 so I am looking for the cleanest/quickest way to disable the heaters.

I found reference to a fuse that controls power to BOTH grid heater relays (solenoids) but I don't know where it is located in my fusebox. (The coils are "hot" via this circuit and the PCM grounds the other side of the relay coils to activate the relays)

Can anyone help with a fuse location?

An alternative is removing the fusible link wire (that feeds the heater relays on the engine block) at the battery terminal, but I don't SEE a separate terminal connected to the battery terminal that can be removed. The terminal has several wires molded into it that cannot be removed, however.

Any help to disable this circuit w/o having to climb into the engine compartment would be most appreciated.

Thanks-

 

[cerberusiam]

Passenger side battery, you will see a large wire, 8 gauge maybe, off the hot post that runs to the relays. Disconnect that and it will stop the grids from heating.

 

[Ozymandias]

Double Thread, other one has 8 answers.

 

[bobinyelm]

Yep- I was looking on the WRONG side.

When I looked on the right (correct) side there was the forked fusible link.

Unfortunately, it didn't solve the problem I was having (my Air Dog lift pump motor changes speed and sound for about the first 2 min after eng start).

I wasn't sure if the best place was the 911 or the general forum, sorry.

 

[BigDaddy]

This is normal operation for any stock or aftermarket fuel pump however 2 minutes seem a little long. When first turning the key on or bumping the starter the fuel pump should motor for 45 - 60 seconds. Towards the end of the cycle the fuel pump will change sound as it reaches rated pressure. The fuel pump is controlled by the computer and there is no adjustment. Double check the fuel pump run time with a watch/timer.

I do not think your fuel pump is bad or has anything to do with your problem.

Are your batteries fully charged. This may result in a long pressure buildup time.

To clarify; I believe the grid heater wire should be connected to the drivers side battery.

 

[BigDaddy]

BTW, This is the right forum to post your problem.

 

[bobinyelm]

I've had the Air Dog on for 6 years and it stabilized inside a second up until now and never warbled at all.

Now, it sounds stable until the engine starts, then after start the pump motor makes choked-goose sounds for up to 2 min before stabilizing.

A couple of times it started, then immediately died, and continuing to crank did nothing. I released the key, and re-activated the starter and it started instantly and kept running. Never did that before, either.

SOMETHING changed.

 

[BigDaddy]

Do you have at least 5 gallons of fuel in the tank and are you sure your fuel gauge is accurate? These tank sending units are known for their short life expectancy.

I have the very first Air Dog and never a glitch. It has to be 12 years old. Not to say they are infallible. It's that initial sound and then clearing up makes me think of low fuel level or clogged fuel filter and/or strainer.

 

[bobinyelm]

Yes on the gauge, but it wouldn't hurt to service the filter/strainer.

The factory recently told me 5-6 years as the useful life (mine is 6).

They said ULSD fuel is eating the seals and fuel is getting into the motors. New ones have fuel resistant seals.

It was the ORIGINAL manufacturer who told me this, BTW. They sold the rights to small pumps to the NEW company about 5.5 years ago and just do over-the-road pumps now.

Call 'em w/ your serial # before yours quits! They will provide you w/ a new motor/pump Assy to mount on your filter block.

 

[BigDaddy]

I use Howe's Lubrication and Anti Gel since the truck was new. It takes up what the ULSD loses. I should be ok... knock on wood

Just in case, who is the new company?

 

[bobinyelm]

The "new" company is the one you see if you Google "Air Dog" :

http://www.pureflowairdog.com/

but the old company BIG trucks only is:

http://www.pureflowtechnologies.com/

Very similar sounding, but a different company

They said it is not low lubricity that eats the seal, but ULSD has more of a solvent property that softens and dissolves the old material.