Since it is a 2001 make sure you do a close inspection of all rubber fuel lines. If they show cracks they will need to be replaced. The cracks will allow air to be drawn into the lines. Also there is a fuel filter at the generator, make sure it has been replaced. The fuel pump can be tested by pressure or volumn of flow. Also a fuel line from a gas can to see if the generator runs from another fuel supply. As for the connection on top of the tank I am afraid that the only way to check that fitting is to lower the tank. Sometimes the brackets can be loosened allowing the tank to drop low enough without removing to inspect the fittings. Do not forget that the generator fuel pick-up only goes to the 1/4 full mark so it will not run the tank empty from the generator.