M-series injection

smn53 said:

I'd like to get an M-series running and don't want the oil injection just yet. While troubleshooting this thing I don't need it on. What do I need to do to it to bypass the safety switch? Can I just unplug the wire harness to bypass that switch so it will run?

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Yes, just unplugging it will allow the engine to run with no oil in the tank.

Oil injection is great if it works properly. But as stuff gets old, you start to wonder whether or not to trust the oil pump. My 1978 Suzuki Dirtbike still has oil injection and it still works, but my last M-series Lawn Boy apparently didn't work because it was unhooked and premixed by the previous owner. Find yourself a commercial tank to put on your M if you aren't going to inject it. It will run all week on a tank of fuel!

I recommend anyone running an injected M to pull the flywheel and pump cover to inspect and regrease the pump gears. Doesn't take all that long for peace of mind and added insurance to keep the gears lubed. You can also make sure your pump/throttle is calibrated correctly to factory specs at this time.

Oil is injected into the oncoming air fuel mixture by a flat plastic plate with a check valve in it between the block and the carb. I have one that leaks down due to the check valve malfunctioning and allows a lot of oil into the crank case. Upon starting it will spurt droplets of oil out the exhaust for a real mess. I have the new plate and check valve assy by have not installed it yet. These mowers have no equal in quality of cut IMHO.