Chassis cab aux tank

[BigLakeDMAX]

Has anyone looked at or actually installed the aux fuel tank from a chassis cab into our trucks? Obviously it would mean moving the spare from its OEM location to an alternate location. I've checked the Helms manual and it looks as though our ECM's are set for the additional sending unit input from the aux tank and the fuel pump relay exciter circuit. In fact, I checked and there is already a fuel pump relay installed in my under hood power center which I believe is for this purpose - I removed it to check and truck ran fine without it. Chassis cab aux tanks can be had for $100 - $200 from crashed trucks or as take offs. I believe capacity is 20 US gals.?

I already have a short box and don't want to lose any of it to an in-box aux tank, have looked at the TransferFlow replacement but would prefer to keep all of the ground clearance I can as I do do some off-road when hunting.

Looks like one issue would be where to mount the fuel filler for the aux tank. The spare would just be moved to inside the box, verticle mount, in front of a wheel well like we used to carry them. Don't lose alot of box space for that.

[Phil Holmen]

Could possibly hinge one of the rear tailights and put the filler neck in there...just a thought...

[Jelisfc]

I looked at a chassis cab last week. It looks like a simple install. Of course looking at a bare chassis is different than with a box. I was thinking just running a toggle switch. The fill neck must have been 3 feet long. I see you have a topper or cover. I wonder if you could fashion a trap door on the floor of the bed behind the left wheel well. If you had a sheetmetal box made you could seal the door so fumes couldn't get into the box but whisp away under it.

[BigLakeDMAX]

For a filler location, I've considered mounting it inside the driver's side rear wheel well - one of the big 3 used to do that IIRC, or perhaps behind the rear license plate which I'd have to mount on an adapted spring-loaded holder like some cars had. I'm also considering an in-box mount as you suggest. I'll have to see. I'm going to play some with testing active circuits this weekend to determine if everything on the 2500 works as it does on a chassis cab.

Does anyone know if the aux tank on a chassis cab has just one fuel line - the transfer line to the main tank, or is there a return line. And, where does the transfer line from the aux tank connect to the main tank? I've checked a couple of dealer lots but as yet haven't found a chassis cab to look at.

Thanks!

Don

[77TransAm]

BigLakeDMAX, the aux tank uses two lines - a large one with a transfer pump inline, and a smaller one which appears to just be a vapor return. They connect to a fitting in a separate hole in the main tank that does not seem to appear on single tank trucks.

If you'd like I can email you some pics of both tanks as well as the transfer pump mounting location.

[BigLakeDMAX]

77TA - Thanks for the info. Some pictures would be great if you have some. My email is dabbott@sherbtel.net

Thanks again. Don