Cleaning out Auxiliary fuel tank

[husker77c]

So I'm heading to PA tomorrow to pick up the 12 valve donor truck and all my tools.  I'll be able to get my 105gal transfer tank finally for the bed of the Zombie 350.  Some history about the tank.  I bought a utility bed for my 3500 and the tank/toolbox combo came with it.  I never put fuel in it or even took the cap off of it.  I'm wondering if I should attempt to clean it out before I put fuel in it.  What would be the best free way to accomplish that?   I knew a guy who welded a steel tank for his truck and he used water to leak test it and he said it was a big mistake due to constantly having water in his fuel for months. I'm kind of thinking of blowing it out as best I can with air and then just running fuel in it.  I will be using a 12v pump that came with it to transfer fuel when the time comes so I will put a filter on the output side of that to catch any debris. 

Thoughts ideas?

[Sammconn]

I picked up an oldie a few years back.
I 'donated' one filter to the cause of a tank flush.

Put in about 40 or so gallons, sloshed it around some and then ran the pump in a circulate fashion back into the tank.
Now I knew this tank had previously had diesel in it, so it was as much to get any gunk out of suspension.
If I were you I'd likely want to drain it, then do a visual as best you can to see what you are up against, and proceed in this sort of fashion. As long as it's decent, all you're out is a filter.

[cudakidd53]

What about putting some cheese cloth in a funnel and transfer it into another container after adding some fuel and sloshing around awhile?  Catch the big chunks and get to inspect it visually as it empties.  Then the filter can catch the rest and you should be GTG

[TexasRedNeck]

Empty, inspect with flashlight or inspection camera.  It you see rust and such...

http://www.kbs-coatings.com/tank-sealers.html

[husker77c]

I picked up an oldie a few years back.
I 'donated' one filter to the cause of a tank flush.

Put in about 40 or so gallons, sloshed it around some and then ran the pump in a circulate fashion back into the tank.
Now I knew this tank had previously had diesel in it, so it was as much to get any gunk out of suspension.
If I were you I'd likely want to drain it, then do a visual as best you can to see what you are up against, and proceed in this sort of fashion. As long as it's decent, all you're out is a filter.

Did you run the 40 gallons or dispose of it?   It's an aluminum tank so rust shouldn't be an issue.  It also should be empty but i won't know for a couple days till I get up there to it.  The cheesecloth idea seems like a good one.

[Sammconn]

I ran it. Filtered for an eternity it seemed, and said well, let's see. Was good to go, no issues and no filter issues on the truck either.
Yes the cheesecloth is a real good idea too. Would save the donor filter some too.
With the aluminum tank rust shouldn't be an issue, but there could be crusty chunks of nasty in there. Empty it if it's not and give as good a look as you can. It may look perfect and may not, but either way I'd put a 'rinse' quantity in to give it a wash.
Use a quality filter and you should be laughing.