I had a problem with a thick tar that was built up in my fuel tank. It was slowly contaminating the fuel (turning the fuel a coffee color) and causing my motor to shut down with clogged carbs. Had to have them cleaned twice in two weeks!!<br /><br /> I discovered the fuel tank I have is made by Pate Plastics Inc. in Miami, Florida. The tank was in the boat when I bought it two years ago. (She is a 1983 Boston Whaler) She sat for a year after I bought her and no telling how long before I bought her. Anyway Pate told me the fuel broke down over the years to foorm the tar that was in the tank. The Pate tank is fiberglass and I was apprehensive about using a harsh chemical to clean the tank. (I had a post here a while back). <br /><br /> Pate said to put a gallon of acetone in the empty tank and swirl it for about 15 minutes or so. Then rinse with a 1/2 gal of gas, twice.<br /><br /> What a difference it made!!!! The acetone came out alomst black with tar. The first rinse was coffee colored and the second was alomst clear. I've got her drying now and I'll rinse her in the morning again. I ordered a new tank and plan to use the old one for storage between trips to the gas station during boating/fishing season.<br /> <br /> Thanks to everyone who posted the helpfull information last time.
