Originally Posted By: Pop_Rivit
How many normal shutdown cycles does it take to foul the plug and wreck the oil? I'd be interesting in seeing the side by side comparison of engines that have been shut off with a deadman brake vs. normal shutdown. Where did you find the research?
Back in the day I had a 1982 cadillac cimarron with a nightmare computerized carburetor and one of its features was a solenoid that shut off fuel when the key was shut off so it wouldn't diesel. This alerted me that some powertrain engineer, somewhere, concluded this was worthwhile. Now cars have fuel injection and this isn't an issue... though, anecdotally, you could find a carb'd car that ran forever.
In the last 20 years I've run deadman mowers and thought, yay, I'm a genius, by releasing the handle halfway, killing spark, and letting it coast to a stop, and saving the stupid little brake. Then I started getting free mowers from the dump where the deadman seized as it's the poorest engineered bit on the (briggs) engine. I get them running again and realize it doesn't matter.
To then justify to myself my sudden and abrupt releasing of the handle, I'm happy to not suck this fuel through.
On another tangent, my "Chonda" engines instruct the operator to slow to idle, a feature unavailable on my mower, before shutting down, unless it's an emergency. This means less coast-down time. Less fuel to suck? Ask their engineers!