Turned on the pump today and water started spewing out the city fill where you connect the hose....any ideas? Is there a back flow valve somewhere that could have failed?
Yes, there is a check valve on the city fill line. Your valve has stuck open. You can add a cap to the fill line until you can replace the check valve.
Do you know where the check valve is
by chance?
Doug, On a GV the water check valve SHOULD be right at the bulkhead where you attach the hose. It's probably a silver or chrome looking plate with the female hose connector mounted. Look in this opening if there is no screen and there should be a plastic device that acts as a check valve. As a temp measure screw in your hose with a closed nozzle on its end, after the hose fills you will have pressure in the House system.
If this is the type check valve you have you can probably change it out by removing the screws that holed it to the bulkhead and then pull it out far enough to unscrew it, replacement will probably have to come from a camping world type store.
Good Luck
Gary B