Dear SnowRidge,
There is the possibility that your new fuel dissolved something out of your gas tank, but if you haven't been seeing fibers and debris before, I would bet on the fuel. Any petroleum fuel is susceptible to growing bacteria. Often the bacteria grow best on the interface with water at the bottom of many underground tanks. Over time, if the station isn't actively trying to remove the water, you can get substantial accumulations of fibrous material from the bacteria. Obviously, if you get the gas from a station that has new tanks and does a lot of business, you are less likely to get into trouble. Oh, and it helps if you get the gas in an area with low dew points, like Arizona.
In general, it is much more of a problem for diesel fuel which is much more hydroscopic than gasoline.
If you have the misfortune to get fuel from low in the tank, or just after a tanker delivery has mixed it up, you can get a slug of this material. You can also get debris because by the gas station switching to a higher ethanol blend E0 to E10 or higher. The ethanol dries up the water, and the fibers are set loose in the gasoline. The ethanol is also good at dissolving up material that has precipitated from the gasoline. (Good for you in the long run, but not if the gas station switches to the higher ethanol fuel without cleaning out the tanks.)
Gas stations are supposed to flush and clean their gasoline tanks when they switch to E10 or higher ethanol mixtures, because the ethanol is very good at dissolving sediment and gunk from the bottoms of gasoline tanks. Some states mandate this, but not every state.
Regardless of the cause of the sludge, you were probably unlucky enough to get gasoline from a station that hadn't flushed their tanks.
It is a general problem for gasoline tanks;
US Tank Alliance | Tank Cleaning and Ethanol Conversion
but an abrupt change to E10 or E85 without cleaning can dissolve up a lot of gunk.
I also try not to get gasoline right after the tankers make a delivery for similar reasons; who needs to have extra gunk washed into your tank, and your fuel filter?
Given all of the vapor lock issues with the 425, I wouldn't be rushing to put E85 into the tank, despite its advantages for carburetor and tank cleaning, because of the higher vapor pressure and the increased octane, neither of which you need.
All the best,
Peter
My PT-425 quit on me today. Turned out to be the elbow fitting on the bottom of the fuel tank. It was clogged. I also saw a few strands of scum floating in the tank, something I have never seen before. I think the 10% ethanol "gas" is behind this nonsense.
I've noticed a couple of stations with big signs proclaiming their fuel to be 100% alcohol free. I think next time I buy gas for the PT, I will try the alcohol free stuff.
