on the 5500 there is a PRIME position on the start/stop switch, push and hold the STOP/PRIME button down and listen for the pump to start clicking, this will indicate that the pump is pumping and will soon prime itself. When the clicking stops or slows down, let go of the switch and press the START BUTTON. should start after 15 to 30 seconds. Just a suggestion. But back to your question, have you actually used a volt meter while trying to start the genset to determine that you have no voltage? could be that you lost your prime and if those 5500 sit ( 4 weeks or more) for a while the carb will go dry and you have to prime in order to start. Give it a try.