Wipe away dirt from all parts of the generator with a rag. As you go through the troubleshooting, gently clean the parts of the generator.
Check to see whether the fuel line is intact. Visually inspect it to see whether any fuel is leaking. Check the line and the seals where it meets the fuel tank and the engine. If the fuel line is leaking, it will need to be replaced with a new part because the entire fuel line likely is corroded.
Check that the fuel tank is not leaking fuel. If it is, determine where the leak is coming from by removing the tank from the generator, emptying it of gas, submerging it in a bucket of water with the opening facing down and looking for bubbles. Determine where the hole is and apply epoxy. Allow the tank to dry completely before refitting it on the generator and refilling it with gas.
Check to see whether the generator can be started by pulling on the choke and the electric starter. If it doesn't start, the fuse for the remote starter switch likely has failed and will need to be replaced with a new part. Locate the fuse, pull it out and snap a new one in place. Location depends on the model of generator.
Check to see that the air filter is clean and not clogged. If it has a problem, it will need to be replaced with a new air filter by pulling out the old part and snapping a new one in place.