My fuel gage has never worked. Bought boat 5 yr ago po replaced fuel tank but hooked up gage. Wires are hooked to sender but not to gage. what turns on gage light and gage? must the ingition switch be on or is their a breaker on the panel that turns the light onthe switch. Can i test the gage by hooking a wire directly to battery term.and the sender wire to the sender post.