Although I enjoy the show, The Walking Dead really stretched the truth in many ways. They had people driving cars YEARS after the world crashed using gasoline that was several years old.
That would never work here in California.
Our gas is "Up to 10% Ethanol". Testing has found it to be approximately 6% as of 2 years ago. I've read that the Ethanol gas has a shorter shelf life than pure petroleum based gasoline.
I have had a persistent cold start problem with my Charger for several months. The last time I drove it to a gas pump was early this year. Since then, I've driven it less than 100 miles. I've been working on several things with it including a new Classic Auto Air heater and A/C system, wiring upgrades, windage tray, radiator, water pump and housing...all sorts of things. Because of that, the gas in the car got old.
So, since about June of this year, it ha been hard to start and when it did, it ran really rough. The Air/Fuel gauge read really lean as well. It slowly smoothed out as it got up to temperature. Once it was warm, it ran great. The Air/Fuel readings read rich as it warmed up, with numbers in the 12 to 12.5 range.
I looked for the causes of the rough cold idle. First off, I did NOT have a choke on the carburetor. This Demon 850 always allowed the 440/493 to run pretty good at cold starts without a choke. 20-30 seconds of feathering the throttle and it would run on it's own. The rough running felt like a serious misfire, as if 4 holes were just not getting spark. I swapped parts around including the distributor, spark box, ballast resistor, coil and I even tried a different carburetor. The Holley 750 from another car was the only thing that made a difference. With it, the engine ran like it used to before any of the problems started. I had my Demon rebuilt and the man installed a new electric choke kit. Yesterday I put the 850 back on and the car ran just as bad as it did before. What the heck?
It turns out that this 11 month old gasoline was the problem. Today I drained the tank and the bowls of the carburetor and poured in fresh 91 octane gas. The car runs great again.
Why did it run good with the Holley 750? I think that it was because it still had gas in it from the other car!
MY understanding, after reading up a bit, is that as gasoline ages, it evaporates and loses the volatile compounds first. This leaves behind a thicker, yellower and less potent blend. Cold starts need MORE fuel than a warm start. The fuel needs potency to ignite.
I guess I'll keep some Sta-Bil on hand if I think the car will sit for more than a month.
