Rule 3700 sump bilge air lock

[enproep]

Hello: I have a Carver 530 Voyager and have an issue with my sump box bilge pump. It seems to get an airlock and continuously run not sucking up any water. It works fine while at dock or at a very calm anchorage. Basically, while sitting at the dock, the water in the sump box remains low and level, switch is only on with incoming grey water. Nothing to pump unless the float is tripped from incoming grey. Head out to sea, the same amount of low water remaining sloshes indicting more water than is actually there, the float switch turns on the pump, and the pump sucks up water and air until it stops sucking up water for some reason (the air it sucks up creates and airlock possibly?) It then runs continuously without sucking up any water. When we get back to the dock we can take a shower and the sump box fills up and overflows even with the pump running (it's running but not sucking up water). I then disconnect it (cut a power wire) and then reconnect it and it works fine.
Any suggestions?
Thanks in advance, Bob

[waybomb]

How about raising the switch?

[Lyndon670]

Is there not a baffle(s) in it to stop the sloshing? I'm pretty sure mine has opposing baffles.

[voyagerfan]

You can "burp" the pump and release the trapped air by releasing the two hold-down tabs on the side of the pump and tilting the pump slightly while the water in the tank is at least 1/2 way up the pump. The ultimate fix is as suggested by waybomb - raise the float switch position relative to the bottom of the tank. There is a single screw holding that switch to the bottom of the tank that has some play in it.