Outdoor Power Equipment and Small Engines - Murray Rider not running

I have a Murray 20 hp rider that went silent as I was cutting the grass and coasted to a stop. It didn't sputter or anything, I checked the gas flow anyway and all looks good. A couple of weeks earlier I had removed the deck to clean it and sharpen the blades and when I connected the deck back to the mower, it wouldn't start, no sound. I figured it was safety related so I took it back out checked everything again and put it back in place. It then started and I had no issues until it quit. I unplugged the two safety switches I found to see if that would work but it didn't help. It sputtered for about 5 seconds but then quit. I tried again with the safety switches plugged and unplugged but it just continued to turn the starter.

I took out the two spark plugs and replaced them but no change. I then took each one out separately to see if it was getting a spark and I did see a spark, but after it backfired on me I decided I needed to seek the assistance of the DIY team.

The mower data: Murray - 20 hp Briggs & Stratton Diamond I/C engine

Mower Data:
Model # 52431X92
Serial # 7375000282N00536

Engine Data:
Model # 460777
Type # 2277 E1
Code # 9712165A

Thanks

Hello tnmike53!

Does the engine crank over with the starter? Do both cylinders have compression? Has the flywheel been removed in the recent past? If you verified that you have spark on both plugs, then try squirting a little gas into each plug hole or in the carb intake and see if it will start and run for a second or two.

Hi Cheese, The flywheel has not been changed and the engine turns over fine but will not catch. I tried the gas suggestion but there was no difference. The engine turns over but thats all.

Sounds like your engine is not getting fire. I would next dissconnect the coil kill wires and see if the engine fires up. Mabie a wiring problem. Do that and will work from there. If you don't know where the wire is, locate the coil or coils. There should be a black wire coming off of them. Le us know how it goes. :)

Have you got good compression on both cylinders? How do the spark plugs look? (wet, oily, sooty, etc...)?

The plugs in it are new, the ones I took out looked good, no oil build up or soot (some but nothing you wouldn't expect after 5 years).

:confused: Where is the coil? I see the starter and solenoid but no coil.

Thanks

You'll have to remove the engine shroud to access the coil. (the cover on top of the engine).

:confused: I removed the shroud but still am not sure what the coil looks like. I checked a website for the electrical components but didn't see a coil listed, is there another name for the coil? Is it near the armature or starter?

Thanks

The coil is where the other end of your sparkplug wire goes into. Do you see it? Folow your sparkplug wire to the coil. Then you should see a small black wire coming off of it. The coil kill wire is a grounding wire. If you remove it, it will eliminate problems caused by saftey switches, etc.

The coil and the armature are one and the same (all one piece).

The small wire I located running from the coil had what looked like a fuse connector, when I pulled it apart it turned out to be a male/female connector. I left it unpluged and tried to start the mower, I thought for a second it would catch but it backfired instead. I tried it again and got the same result. Did I unplug the right wire or does this speak to another issue?

Sounds like you got the right wire. Verify again that you have good spark on both plugs, and make sure the spark is from the electrode to the plug end. (not between the metal on the plug and the metal on the engine). If you have good spark, for certain, then I think checking compression would be the next step.

Okay, I pulled each plug out (separately) and tried to start it, the engine turns over then backfires, but I was able to see sparks from each plug.

So how do I check compression?

An easy way that would be sufficient in this case (non-scientific method :D) would be to remove both plugs, move the plug wires out of the way, and hold your finger over the plug hole firmly, but not with all your might. Crank the engine. If the engine is able to blow air past your finger easily, then you should have enough compression for it to run.