Auxiliary fuel tank and water separator question

[jcm3]

I really appreciate the expertise in this form, and have been OD'ing on it for the last few months.

I just picked up a very clean 2005 F250 crew cab that had already been bullet proofed (sweet), and had some suspension work done for towing. It was a great find.

My question is regarding the auxiliary fuel tank. I'm still a newbie to the diesel world, but am trying to come up to speed fast and have been on the internet a lot in the past few months.

I am getting ready to do the fuel filters and an oil change this weekend, and was tracing the lines from my auxiliary tank under the frame rails. There is an inline fuel filter of unknown origin currently in line, a silver metallic filter that looks kind of like this:




I need to trace more, but I didn't see any kind of water separator there, and am concerned about injectors. The line from the auxiliary tank is on the opposite side of the truck than the stock water separator/filter unit, so I'm 99% sure it doesn't go through there. I'll have to double-check.

Is there a good inline fuel filter that also acts as a water separator? What kind of other things are the folks on this forum doing who have auxiliary fuel tanks in the bed?

Thanks for any info.

Here are a few pictures of my new beauty:

[jcm3]

Bumpidy bump...

[rufushusky]

Where does the aux tank tap into the fuel system? I didn't run any kind of fuel filter on my aux tank but I tapped into the filler neck of the truck using the RDS kit so it didn't by pass the fuel filter. (Not that is really possible on a 7.3). The easiest thing to do might be to fine where the tank ties into and move it pre-pump and WS.

[jcm3]

Originally Posted by rufushusky

Where does the aux tank tap into the fuel system? I didn't run any kind of fuel filter on my aux tank but I tapped into the filler neck of the truck using the RDS kit so it didn't by pass the fuel filter. (Not that is really possible on a 7.3). The easiest thing to do might be to fine where the tank ties into and move it pre-pump and WS.

Good call. I don't actually know, but I'll get under there this weekend and try to follow the lines better. I'm confident that it ties into the fuel filter in the engine bay, but I don't know if it ties into the system before the filter under the bed.

The one in the engine bay doesn't have a water separator, does it?

Thanks for your response.

[rufushusky]

Originally Posted by jcm3

Good call. I don't actually know, but I'll get under there this weekend and try to follow the lines better. I'm confident that it ties into the fuel filter in the engine bay, but I don't know if it ties into the system before the filter under the bed.

The one in the engine bay doesn't have a water separator, does it?

Thanks for your response.

I am not a 6.0 guy but to the best of my knowledge it is a nominal water stripper at best. That duty is supposed to be handled by the primary filter on the frame rail.

How the aux tank set up? Is it a gravity feed tank or a suction type? Basically do the lines come from the bottom of the tank or the top/sides?

[jcm3]

Originally Posted by rufushusky

I am not a 6.0 guy but to the best of my knowledge it is a nominal water stripper at best. That duty is supposed to be handled by the primary filter on the frame rail.

How the aux tank set up? Is it a gravity feed tank or a suction type? Basically do the lines come from the bottom of the tank or the top/sides?

From what I saw when I was under there, it comes from the driver's side of the fuel tank, down through the bed and along the frame rails. I'm pretty sure it is not gravity feed, and has its own pump. But, when I was under there, I wasn't looking very closely, so I'll have to analyze it much better and maybe take some pictures.

Your idea to feed it in before the primary filter is a good one, and I'll see if that is possible. I'll get under it this weekend and poke around.

Thanks again!

[jcm3]

OK, diesel newbie alert. (me)

I checked it out, and I was wrong. The lines from the auxiliary tank do go into the stock filter setup, with the water separator. It also looks like it is not gravity fed, as the fuel lines exit from the top. It's a KSH Fuel Products 100 gallon tank. I checked out their website, and they look like quality products. (100-Gallon)

The lines come into what I assume is some kind of a tee that combine the four lines down to two. I assume this is the part that is activated by the toggle switch under the steering wheel that switches from the stock tank to the auxiliary tank.

Sorry for the crappy pics, it was dark outside and hard to see.

[jcm3]

I do have a few questions that I'd be interested in getting thoughts on:

- Is there any concern with the small inline fuel filter that is on the aux tank line, before the factory fuel filter/water separator? Could it slow down flow at all?

- Is there a specific type that I should look for when replacing it? I don't know if it's ever been replaced, so I'm going to do an oil/filter change, as well as change all three fuel filters this weekend.

Thanks for any input.

[rufushusky]

Originally Posted by jcm3

I do have a few questions that I'd be interested in getting thoughts on:

- Is there any concern with the small inline fuel filter that is on the aux tank line, before the factory fuel filter/water separator? Could it slow down flow at all?

- Is there a specific type that I should look for when replacing it? I don't know if it's ever been replaced, so I'm going to do an oil/filter change, as well as change all three fuel filters this weekend.

Thanks for any input.

IMHO you have nothing to worry about with the strainer...IIRC it is 24 microns (at Lord knows what efficiency) and purposely designed NOT to restrict flow.

Replacement part numbers:

Fleetguard FF5079
Napa FIL 3270
Wix 33270 (per Wix is 141 microns)

[jcm3]

Originally Posted by rufushusky

IMHO you have nothing to worry about with the strainer...IIRC it is 24 microns (at Lord knows what efficiency) and purposely designed NOT to restrict flow.

Replacement part numbers:

Fleetguard FF5079
Napa FIL 3270
Wix 33270 (per Wix is 141 microns)

Good info, thanks. I'll make sure to replace it with the other two filters when I swap them out.