Re: 1997 Sea Ray 175
My plastic gas tank had a thick layer of old gas that had turned to varnish on the bottom of it. This is from the previous owner, not me. Well, I did my search for "how to remove old varnished gas from a plastic fuel tank" and came up with a several different ways. I'll admit, my gas tank is out, so my job was easier than most.
I have to give credit where credit is due. There is a product called Berrymans Chemtol B12 (product # 0113). It is available at walmart and auto parts stores, it isn't an uncommon product and I've used it before as gas treatment and to clean carburetors. Well, I wasn't sure whether or not it would harm my plastic gas tank, so I called them. They actually put me on the phone with one of their chemists! How cool! Very customer service friendly of them! He ensured me that it wouldn't hurt my gas tank, even non-dilluted.
So, I put a couple of cans of it in my tank and it completely desolved the varnish from the old gas. The what was a clear liquid B12, turned to a brown liquid. I wish I had before and after photos, but it is hard to take a picture through the fuel gauge hole.
Anyway, I was pleasantly surprised by both the product and the customer service of the products manufacturer. So, I wanted to mention it.
By the way, I have a small piece that had broken off of one of the places where you attach the vent hose to the plastic tank (so I have a detached part of the plastic tank) that I submerged in the B12 and let it soack overnight just to make sure, and the B12 didn't hurt the plastic piece at all, so I could've soaked the tank in non-dilluted B12 all night had I wanted to, but it dissolved the varnished old gas within minutes, althought I did let it sit for an hour or so.
So, the project is ready to continue with a functional gas tank now.