Vapor lock can be largely avoided by ensuring that fresh fuel is used in the engine at all times. Gasoline producers automatically change the fuel formula as the seasons change to accommodate for the vaporization rate in different temperatures. In the summer months, for example, fuel companies supply additives which suppress the vaporization rate. Because of this, if you use summer fuel in the winter, there won't be enough vaporization for the fuel to burn. Likewise, winter fuel used in summer will vaporize too readily, creating the bubbles which cause vapor lock.
This isn't a huge issue for automobiles, since most people use their car often enough to necessitate frequent fuel changes. With equipment that might sit idle for months at a time, however, stale fuel can negatively affect machine performance and in turn, alienate customers.
"To prepare any engine for off season storage, the fuel tank should be filled with fresh fuel that has a fuel stabilizer added to it," says Borowski. "Once this fresh fuel is in the tank, the engine should be run for about five minutes to get the stabilized fuel into the carburetor. Once this is done, the warm engine oil can be changed and fresh oil poured into the engine for the storage period.
Nelson suggests that rental businesses also consider setting up a policy, much like rental car dealers do, in which a small surcharge is added to the rental which covers a fresh tank of gas upon return. In other words, your customers pay a couple of dollars more to avoid the hassle of having the gas up your equipment before returning it, and you escape the potential hazards of relying on customers to use fresh fuel in your equipment.
However you do it, for top performance, it's best to ensure the highest quality oil and fuel are used in your gasoline engines.