I have a 410 with a Waterman 500 pump.
I have a low speed bypass off the barrell valve. High speed bypass off the pump. Main bypass off the pump. Shut off valve between the pump and the final filter before the barrell valve.
When I shut the valve, the engine won't die untill I step on the throttle.
I put a new shut off valve on and the same thing.
I put a three way shut off valve with the return going to the tank by it self and the same thing. any clues?