water pump woes

[Real Martin]

would like to know if my water pump is working as well as it should. water is never a constant pressure. lots of spitting which is obviously air in the lines. could the pump be sucking air somewhere it shouldn't be? i know these appliances take a lot of bumping and grinding. the pump doesn't always shut off by itself completely either. sometimes i hear it quietly rumbling and i have to shut the switch off otherwise it will keep on running by itself. wondering if we need a new one. advice ? thoughts ?
Ray & Pat. 35' class A triple E embassy.

[Skip426]

With a lot of air in the system , the amount of line pressure required to have the pump shut off might not be reached .

Is this a new issue or an issue on a new to you RV?

Can you see the pump, checked for water leaks ? Has it got a clear strainer on the inlet side ?

If not properly winterized these strainer housing crack and allow the pump to draw air . There are a couple of types , picture below is one , these aren't supplied with a new pump so if you want to replace the strainer and later find you need a pump you haven't spent too much extra.

[Persistent]

Pump housings also burst when frozen.

Air in water can enter at any point from pump back to fresh water tank (siphon side of pump).

[Old-Biscuit]

Once primed and water flow all air should be fully bleed out of system

Sputtering/not shutting off indicates AIR is being sucked in on suction side of pump
Winterizing valve left open
Suction strainer O-ring leaking
Pump casing cracked
Loose clamps on suction line from tank to pump strainer