Yep, four (4). Not scooter or car but yard/farm type equipment with gas engines.The only reason I even bring it up is the similar causes can crop up in ANY gas engine regardless of size. Two 2-strokes and two 4-strokes.
1. Loss of compression, no start. Was running and shut down for fuel, no restart, free spinning. No resistance to pull start rope. Sidelined until after grass season. 4-stroke Briggs w/ Easy-spin start feature.
2. Failure to run. 2-stroke string trimmer by Echo. Seven years of service, not one failure until now. Still good compression would start and run on choke but faded out when choke opened. Two possibles: pumper carb not pumping or loss of crankcase compression. Was not the carb. One crank seal of two leaking. Seals on order.
3. Chainsaw locked up. Pull starter would not turn engine. Echo 2-stroke worked for seven years. Last use less than 15 seconds then stored. Disassembled to find rust in cylinder! Cleaned cylinder and piston, ring and groove. Starts and runs normal now.
4. Toro zero turn, V-2 Kohler 4-stroke, in use 4 seasons. Fail to start, starter just spinning, Bendix would not extend the pinion. Freed up Bendix but then would not fire. Would fire on propane blown into carb intake so was a fuel problem. Pulse fuel pump worked so drained carb float bowl and removed. Snot (from ethanol fuel likely) in bottom of bowl so cleaned carb. Original battery would not hold a charge so replaced battery with lawn & garden battery I put in UXV500i. Cut a bunch of grass today!
The longest delays were in getting mail order parts like gaskets and one small roller that disappeared when blasted with compressed air. Go figure! The trouble shooting logic is the same no matter brand or type engine. The only differences is recognizing the differences in the systems and proceed from theory of checks to either prove or eliminate each possibility. Avoid repeats unless an error in either proving or eliminating suspected. Like on the mower. There were THREE things wrong! But each one was discovered and proven in sequence. Grass and weeds are HUGE! I will be busy outside well into November with the fading dry spells!