I can attest to the varnish that forms when gas is left sitting for too long
exposed to the air. I neglected to drain the gas from the carburetor in our
lawnmower before it sat for two years. This spring I filled it with gas and
as soon as I started it gas started shooting out the priming bulb.
According to the small engine shop this is a "failure mode" when the carb is
gunked-up. [dunno] I had the shop clean the carb and it still doesn't idle
properly until it is fully warmed. I immediately put fuel stabilizer in the
snow blower and it started on the first pull last week (it sat for 9
months). One of my winter projects will be getting that darn lawnmower to
idle -- I have to manually rev it now to keep it from stalling while it
[mailto:email@example.com] On Behalf Of David Scheidt
Sent: Wednesday, December 21, 2011 5:30 PM
To: Bob Spidell
Subject: Re: [Shop-talk] Storing Gasoline; was: Re: OT--car won't start.
Gasoline 'spoils' through two processes. One is evaporation of the lighter
fractions. The other is oxidation of the component parts.
You can add antioxidants to keep that from happening, which is what sta-bil
et al are, among other things. Depending on what's in the gasoline, the
oxidation can produce gum and other nasty stuff (why bad gas turns brown).
What's in gasoline depends largely on what the base oil was, and what the
refinery did. There are rather substantial differences.
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