Lx178 runs briefly, then shuts off abruptly.

I got a John deere lx178. It has a problem where it (previously) starts right up, would run anywhere from 5 to 30 seconds, then just shut off like you turned the key, doesn't bog or anything, and then would start again if you turn the key immediately after it shuts itself off. But it's also inconsistent, sometimes it runs 5 seconds, sometimes it'll run over a minute, and the last time it wouldn't start again at all. I haven't tried cleaning the carb yet just because it looks like a pain to take off and it sounds like something electrical. Was hoping someone knew more about these engines and could point me in a direction before I just start tearing things apart.