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Model 71188 12-32

The previous owner claimed it ran last year but it just needed a battery. Long story short I said if you can allow me to put a battery in to try it and see if it runs, you have a deal. He said he had a new one from his other mower and would put it in. He called back 10 minutes later to say it cranks but won't fire. I said as long as I have your word it ran last year, we have a deal if you throw in that battery.

Fast forward when I finally get it home. It cranks, has spark I am almost certain it has compression, but just won't start. There are 3 sets of plugs that are unplugged that I have no idea where they go. one Blk/Wht single wire, One Gray - One Red/Wht double wire plug and One Black - One Brown double wire plug. I downloaded the schematic but it's not helping me, I have 3 female plug ends with no male ends to plug them into. I attached pics for you to see. So I had a good mechanic friend of mine stop by. I go to crank it and no more then 2 seconds into it, the motor just stops (mind you I was working on it for 2 hours before this with no issue). Turns our the the blade was engaged and was all of a sudden hitting the inside of the mower housing. My friend said it would be wise to check to see if the woodruff key for the flywheel is sheered. He said if that happened during mowing the momentum of the flywheel would keep it turning and throw the timing off. Unfortunately I did not have the correct socket size to remove the bolt on the flywheel to check the key. 25 mm I assume?. So my hope is the timing is just the issue, but I am thinking this guy lied or something worse happened he's not disclosing and tried working on it himself. There are no screws holding the upper shroud along with all those plugs unplugged.

Any help would be appreciated.

Thanks!

Well since you have spark, the only reason the wiring could be an issue is if it has a fuel solenoid on the carb that isnt connected. The extra connectors could just be for headlites, hour meter, extra gauges etc. If no solenoid then I would say your friend has a pretty good idea.

Bod said:

Well since you have spark, the only reason the wiring could be an issue is if it has a fuel solenoid on the carb that isnt connected. The extra connectors could just be for headlites, hour meter, extra gauges etc. If no solenoid then I would say your friend has a pretty good idea.

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Update: My friend was right...about the sheered key that is. I replaced it and cranked it to find it still wouldn't start. I then realized I had no compression. Looks like a broken rod, or at least I hope that's all it is. I should mention, the crankcase was flooded with gas when I got it. This same thing happened to my old mower and it eventually seized the motor. So my guess is the previous owner didn't realize it was loaded with gas and cranked it causing it to have no lube and back fire sheering the key and braking the rod.

I am no stranger to tearing apart a motor and the rod is cheap enough so I will go ahead and replace it. The mower was still worth the money IMO.

Sorry to hear about that, but it is a common failure (gas leaks into engine, hydrolocks cylinder, contaminates oil) that both of my neighbors have lost riding mower engines to. I now install fuel shutoff valves on every piece of equipment with the fuel tank higher than the carburetor to prevent this from happening.

Make sure to check your other bearings too - hopefully it was hydrolocked and broke the rod quickly and didn't cause other bearing damage from running it with the oil being too diluted by gasoline.

SOP with every mower that comes into my shop is to fit an inline fuel tap.
If the carb is leaking between mows you will notice it as it will stink of fuel.
But between seasons or extended no mow periods it is a different matter.
I try to get thenm to shut it doff and let the engine starve when they have finished mowing.
Also this helps prevent bad fuel / water contamination between mows.