Flushing gas tank.

[Holdemhook]

I drained the plastic gas tank of an old boat that had sat for 5 years it had lots of water in it. I accessed the gas through the sending unit and seemed like I got it all sucked out using a wonder pump I than added fresh high grade gas to the empty tank and added some STP gas treatment. The next day the gas in the tank is a dark orange color, the old gas that was pumped out looked clear I'm wondering if the fuel treatment absorbed contaminants from the tank. Also wondering what to do next do I drain the tank again and refill with fresh fuel or just top off existing discolored fuel ? Thanks in advance.

 

[gm280]

Does the new gas smell odd? If not, is this on a 2 cycle engine or 4 cycle? If two cycle, did you add the oil? Either way, if it smells like gas, it shouldn't matter. But only you can make that determination. Usually folks use Stabil or some other gas stabilizer. I have no idea what type STP treatment you used... IDK :noidea:

 

[BillP]

I just cleaned an old (15 yrs) portable Attwood tank that had the orange color with the old gas too. Just looking in the tank at first the gas looked clear. After shaking the tank it turned muddy orange. I added Sea Foam and shook it up again, then let it sit a day before draining. I think the color is partly from the tank. This tank is faded so much it doesn't resemble red now. I would put a gallon or two in your tank again, agitate to mix the bad stuff and drain again. Make sure you have a clear inline filter so it can be monitored. A little sour fuel isn't going to hurt anything if highly diluted with fresh gas. I use high octane when doing old tanks to make up for the loss that old gas has..

 

[Holdemhook]

Thanks for the replys, it's a 4 cycle. It has the vro pump. And it does smell like gas. Not sure what STP it was it just said gas treatment for all engines including boats. I think I will drain it all back out again to play it safe and start fresh. Thanks again