My Coleman Powermate generator runs for ~60 seconds and stalls. It's a Coleman Powermate model PM0435001 5000W with a Subaru EX30D 10HP OHV/OHC gasoline engine. It is nearly 4 years old but has only about 35-40 hours of operation. I have run for it every month or two as per manual except for December through February this winter which had unusual amounts of snow. I have changed the oil and spark plug and cleaned the air filter. It starts easily but only runs for about a minute before stalling whether I open the choke or not. Then I can't start it for several hours. I'm wondering if this might be a clogged fuel line. But I'd appreciate any advice or insights.

SOURCE: I have a Coleman Powermate PM0435001 5000W with a

You probably overlooked the drain plug, it is usually located on the mounting base of the engine. BUT, there have been some engines (old cheap ones) that the oil was drained by tipping the engine and draining out the oil fill. I am almost positive yours is not one of these.

Your manual is here, but that is only an "insert". It does look like the drain plug is located on the base of the engine. Find the spark plug, and the drain plug is almost directly underneath it at the very bottom of the engine.

More information is available from Subaru's website, including owners manual and especially a service and parts manuals. Your drain plug is item #13 on page 2 of the owners manual located here:
http://www.robinamerica.com/pmanuals.aspx?pid=80