Are you trying to bush whack some really tall grass and your lawn mower is not cutting it? Does it start to bog down as you ease into that tall grass and then will die?
Well, the reality of this situation is that you are probably biting off more than you can chew! A self-propelled lawn mower is not a garden tractor that will cut down tall grass. You need to manage your lawn better and cut it on time. Yes, there are times when that is not possible, but it really is a lawn management problem and not necessarily a lawn mower problem.
The problem with tall grass is that it collects under the deck and starts to clog it up. When it clogs up, the blade will stop spinning and that is what stalls out the engine on your self-propelled lawn mower.
Yes, you could have an engine efficiency problem with the lawn mower if the grass is slightly taller than normal and that would need to be checked out. It could be a fuel or ignition problem or it could simply mean that your lawn mower blade needs sharpening.
By determining if the problem is with you or the lawn mower is the first step to resolving the mower stalling in tall grass.