The last stage of my refurb is swapping fuel tanks (and new fairings). I bought a tank on ebay thats in good shape- no internal rust. But, some varnish from old fuel residue. Paranoid about adding new gas and running the crud into the carbs. Whats the easiest way to clean the tank before pitting it on? I poured some carb cleaner into the tank, sprayed the screen, sprayed inside the petcock but theres still that area at the very bottom of the tank thats impossible to drain.

Am i overthinking this?

 

As long as you dont have the petcock installed, I'd say pour some carb cleaner on ther and swish it around.

 

A couple of cans of CocaCola.

 

keep the petcock off, tape up the hole and pour 2 gallons of vinegar in there let it sit over night. then wash it out with distilled water and baking soda, then just distilled water. then to get all the mosture out, dry as best as possible and pour carb cleaner in there, carb cleaner is a quick drying liquid. then reattach everything and pour in the gas. put the pet **** in the open (arrow up) position and watch it pour into the filter.

 

Carb cleaner is not a quick drying liquid you would be wise to use compressed air to spray the residue away or do as i do and ise a full bottle of redex to a single tank job sorted

 

Are you saying you use redex after the vinegar or as a replacement for the whole washing process?

 

Update here on my cleaning. After flushing with a gallon on carb cleaner, reflushing with 3 gallons of 100LL aviation fuel, there were areas in the tank (corners and very bottom) that still had signs of varnish. I ended up taking it to a radiator shop that made a niche in cleaning cycle tanks. Hydrochloric acid since. It got the tank very clean, but with small amounts of flash rust (small random specs on the surface). The guys at the shop said to expect it but also said that dry gas will remove them? Dunno about that.

My other issue is small amount of remaining water from the rinse that's trapped at the very bottom of the tank that I just can't shake out. The tank is in for a paint job and I'm hoping that when the paint shop bakes the tank, it will evaporate the water. If not, not sure what to do.

Guess I'll worry about that after I install the new fairings. Never ending project.