Winco PSS8000 Standby Generator won't start

This question is too vague to give you a good answer. But since it's coming up very high on Google searches, and I recently solved the same problem on the same generator, I thought I'd add a few notes here for others.

In my case, the engine would take a lot of cranking before it would start, and eventually refused to start altogether. If your engine won't even crank, ignore the rest of this, you have a different problem (starter, battery, cables, or solenoid).

I'm also going to assume that you've checked easy stuff like the fuel supply, spark plug wires attached, etc. The PSS8000 runs on propane or natural gas. If it's cranking for a while and not starting, you should smell gas (not gasoline, gas like the gas grill before you light it). If not, then you have a fuel problem.

In my case, all the usual stuff was fine but still no start. The problem was: low compression caused by negative valve clearance. Apparently gaseous fuels wear valves and seats faster than gasoline -- as a result the valve clearance (which is supposed to be a small positive amount) is reduced so the valves are basically held open a tiny bit all the time. This causes several nasty problems, but in my case the main one was low compression. As a result of that, the engine had a hard time starting.

So in addition to all of the usual stuff (plugs, spark, fuel, etc.) check your valve clearance -- you're supposed to do it every season anyway. On my engine the correct clearance is 0.004-0.006" for both intake and exhaust.