There are two issues with 2-cycle lawn equipment and fuel that is used.......The first issue is ethanol, the dry alcohol corrodes the inside of the aluminum fuel components, fuel pumps and carbs on the larger engines, carbs on the smaller engines. I have a friend in the mower repair business and I have witnessed this damage first hand many times in customer units, and the repair cost many times out weighs the unit itself (throw away). The second issue is the oil residue left in the fuel system once the fuel has evaporated over time. The remedy for the second issue, oil residue is usually a simple disassembly, carb. clean, blow out and reassemble, time consuming, but part of owning 2 cycle.
The way to mostly eliminate these issues are first of all, if it is a piece of equipment that is used once or twice per year, fill it minimally for the task, do the work, possibly even adding a little more fuel to finish the job and then let the piece of equipment run until it is out of fuel, dry carb. and tank. <<This gets the corrosive ethanol and oil residue out.
The best option (and it costs more, right now I pay approx. $3.25 per gallon), is non-ethanol fuel in the lawn equipment both 2-cycle and non. Yes it costs more, but my friend charges $55 per hour shop rate and most other lawn repair in our area is $70-$80 per hour, plus the parts if the equip. is worth fixing after the fuel system damage. So in the end, it is pay now, or pay later and if the pay later means throwing a piece of equipment away because the carb, costs more than the value of fixing the equipment then the cost starts to exceed the cost of running non-ethanol fuel in the first place.
I do sometimes wonder if we should have continued to use a lawn service as we had at out previous home instead of me buying a 60" 27hp Z-turn and supporting/quality lawn equipment when we moving into our current house back in 2006?, especially since we are in a subdivision and all of my equip. is wayyy overkill, but I knock out the yard work rather quickly. I'm too deep into it now.
BUT.............In the end, it is that dry ethanol that kills this equipment, and water in fuel. <<Very common at fuel stations, especially at the bottom of the tank. Put that in your lawn equipment and it is down hill from that point.
R