Johnson SPX 1250 gph pump won't lift water

[rollo_cd26]

After over-wintering layup my first sail of 2023 found the SPX pump running continuously with the 3 position switch in auto. Investigation found bilge full and water going nowhere. Suspecting a plugged bilge line, I snaked from the siphon breaker connection to the outlet and then back all the way to the pump. Tests showed the pump failing to force water up 38 inches to the siphon breaker. I disconnected the hose from the pump and ran it in auto and manual, pump gushes plenty of water! Disassembly down to the impeller found nothing broken or amiss. Reassembled, the pump forces a gush of water with force but still won't raise it over bend in siphon breaker! All tests were run in each switch position (auto and manual). I installed the Johnson SPX 1250 gph pump in 11/2018 and it worked fine until now. Johnson specs indicate the pump should be capable of 800 gph at rise of 3 ft. Note: I do not have a backflow prevent valve in the line. Does anyone know if these pumps loose efficiency over time?

CD26D, Lake Ouachita, AR

[Jim Walsh]

It appears your siphon breaker has failed. Just for background I have never used a siphon breaker in a bilge pump hose (though I do employ a vented loop in other applications) nor do I install the back flow preventer supplied with all bilge pumps as they are a flow restriction and I don’t wish to restrict the flow of a bilge pump. I do route my bilge pump hoses as high as possible below decks to prevent siphoning. My bilge is never dusty but I can live with that.