" Your message is a little con
" Your message is a little confusing. You say that the engine will run for hours, but then again you say it will die out after a few minutes. Is your problem one whereas the engine runs for hours, then dies out completely... and won't restart, but if you let it sit for some time it will eventually start but dies out again after a few minutes?
If the above is the case, I'd suggest that you have a spark plug wrench on board, remove the s/plugs when this problem surfaces, then (with the s/plugs removed), check the spark on all cylinders. If there's no spark, find the black wire with a yellow stripe that leads to the powerpack and disconnect it. If you now have spark, in all probability your ignition switch has a high resistance short between the two terminals that are marked "M". A ignition switch with that problem will function but will be intermitent. Replace the ignition switch if needed.
If you had spark when you ran the initial test, obviously the spark (ignition) is okay. In which case, I would suspect a fuel restriction... it would take some time for the fuel restriction to affect the engine initially, but having once done so, it would, after you finally get it running again, affect the engine much sooner. If this is the case, look at the fitting on top of the built in tank where the rubber fuel hose connects. There may be a "anti siphon" valve there. It would be aluminum, about 2" long and the inside portion of it would consist of a spring, ball, and ball seat. It this valve exists, remove it, knock out the inner parts which converts it to a straight through fitting, and reinstall it.
Let me know what you find, and if necessary re-explain your problem a little more percise.
Joe (30 + Years With OMC) "