The original Racor priming pump on our Monaco's had a design flaw. It had a solenoid that would open up and drain any water in the bowl. Mine just opened up by it self and allowed the engine to suck up air into the injectors, coasted to a stop. A referral from Mike Canter suggested I replace it with the 790R30 and I did. It was a plug and play exchange. There IS a Schrader valve on top, turn key on, depress the valve core and push prime button. You will hear the pump start and fill filters. I ALWAYS install my filters empty. I install primary first and prime it, start engine and run for a while, then replace secondary filter empty and prime it for about 30 sec after the pump tone changes to pressurize the fuel system. It has always worked, no chance of getting dirty fuel into the engine this way. Donaldson also sells a primary filter with a clear bowl and drain on the bottom. 40,000 miles driven from coast to coast and NEVER have I had any water in the fuel. I always buy fuel at high volume fuel stations.
2004 Monaco Signature with a Detroit 60, Vorad Radar, Samsung Fridge, Induction cook top, 2020 GMC Denali