Sorry I can't give exact info on relay location, for your coach.
Can you disconnect wiring in the tank area to check for power there?
Be aware that there may be a shut down cycle on the pump , either oil pressure or RPM related , not sure which on your unit , but the pump may only be powered for 10>15 seconds, after key is turned on, if the engine doesn't start, or have oil pressure.
Note that the pump may be brought back to life , by bumping the center of the bottom of the tank while someone is cranking the engine. Big rubber mallet is what I used to use , to get vehicles into the shop, for pump replacement.