Powermate makes generators under the badges Coleman and ProForce. They all function roughly the same and any problems with generators are usually related to the engine. The key to staying out of trouble is to perform maintenance as suggested by the instruction book. This includes checking the oil daily, replacing the air filter at fifty hours, and cleaning the fuel filter at a hundred hours (amongst other tasks).
Check if there is fuel in the tank. If needed, add more. Make sure the fuel shut-off valve is open.
Tighten any loose spark plugs. If the engine won't start, there's low engine output, or the engine runs unevenly, try replacing the spark plug.
Pull the starter rope sharply if the engine won't start. The pulling speed can't be too limp.
Check the oil level. Refill if needed.
Check the grade of fuel is correct and make sure the fuel hasn't been sitting in the tank for too long between uses. If necessary, discard the fuel and replace it.
Make sure you're not overloading the generator. Check that the generator's power output and the power match. If you are running many appliances and the generator is only rated for a few lights, then that's the problem. Check the wattage and make sure it isn't exceeded. For example, one worklight is somewhere between 60 and 100 Watts.