Well I had problems this past season with the fuel sysytem filters in my Promax's getting clogged to the point that they would only idle.Spent a lot of money tracking down the problem that is a whole other story.Well I finally gotr to the fuel senders after emptying the tanks and took them off and holy crap!You would not believe the sludge in the tank.Anyway used muratic acid and filled the tank twice with water.Once to dilute the acid right away,it just ate up the sludge but I did not let it sit but about 1 minute before I started flooding the tank with water to dilute it.I used 1 gallon of acid to 75 gallons of water.After I emptied out the tank I again filled with water until everything was clean.You can eat out of it.Emptied it out and now I am wondering.Should I let it air dry or hook up my shop vac exhaust and runn air through it for a while.The tank is baffled so I cannot wipe down the insides.Any input would help

put some of the gas antifreeze deicer crap in, it has alcohol in it. then put a vacuum on it to move the air to evaporate the moisture.

Tell it brother! I had the same problem when I restored my old Nova.

I used acid as well, but there was still a lot of crap that came out after that. I took my time, and thought it was clean, but it wasn't. Lucas Tune-up in a Bottle additive every tank managed to clear the rest up (nothing else worked as well). I still have a problem with pulling fuel from my one side. I've drained that tank and am going to tear it out again. It will still bog at full throttle when only running off that tank.

I was surprised how much more crap came out after I acid flushed. The first couple of times I put it up on plane, I had to replace the fuel filter. I am not kidding. When you put in on plane, all the crap goes to the back of the tank and heads right for your filter. Go buy a good half dozen! I am not kidding. I think I went through 8 before I stopped having regular problems with clogged filters. I am pretty sure that I took out a fuel pump by being stubborn and not changing them until I had to as well, so I would advise you to at least pull the filter and empty all the crap into a bucket after every run until you get it all flushed out.

To dry out the tanks, I put them in my furnace room (any small room) in my basement, and turned my dehumidifier on max for a day or two. They were bone dry fairly quickly.

Like Ratman said.... some denatured alcohol from home depot or lowes works good. You can buy it by the gallon there in the paint section.