How to Troubleshoot a Coleman Generator
There are a number of reasons why no power is being produced by the generator. In most cases the generator is indeed producing power, but something is preventing it from reaching the item one wishes to power.
Generator runs but produces no power
If the model of Coleman generator is one that comes with a circuit breaker, make sure the circuit breaker has not been thrown and it set. If the breaker throws as soon as it's been set, then there is likely a dangerous fault in either the connecting power cords, or the item one wishes to power. Using different cords, connect an electrical device which is known to work. If the new item doesn't work, then the generator itself is at fault; Coleman customer service should be contacted to see about replacing the faulty generator. If the new item does work, then either the old item or the old power cords are at fault. Check the power cords over thoroughly. Discard them if you find any signs of charring, electrical damage, cuts, or punctures. Try reconnecting the original item one wished to power, it should work now.
Generator slows when load is connected
There are several possible causes for this problem. The first is that one of the appliances connected to the generator has a short circuit, which is hogging all the electricity the generator is producing. Try disconnecting them one at a time until the generator works normally. Likewise, one may have too many items connected; exceeding the amount of electricity the generator is capable of producing. The maximum load varies from one Coleman model to the next, so check the owner's manual to find out. The engine on the generator may be out of use and in need of a tune-up. This will drastically increase the amount of energy the Coleman generator is able to produce.
Generator will not start
A generator functions like any other engine, thus it needs to be taken care of similar to any other engine. Check to make sure that the generator is in the "on" position, ensure that the fuel tank is full of fresh gas, check the oil and top off the oil reservoir if needed, clean the air filter and make sure the spark plug wire is connected firmly to the spark plug. If this doesn't help, unscrew the spark plug and hold the contacts next to a metal surface, try to start the engine. If the spark plug fails to generate a visible spark, it needs to be replaced. Should the spark plug not be the cause, the engine may have lost compression; the throttle valve in the carburetor could be stuck, causing a bad fuel/air ratio. In all these cases, the generator must be seen to by professional service people.