water pump woes

[erice]

i've been flushing out my 2 fresh water tanks, but when one tank is run dry, the pump won't easily start pumping after i switch to the second tank. i've taken off the inlet hose and sucked water through then reattach to pump, but it would not pump. i then took off the outflow hose & it was pressurized! this happened several times, with 1 or 2 times pressurized air coming back out. this happened even after i opened the faucets with nothing coming out. any ideas?

[RobS]

Could be sucking air, any leaks?
How old is the pump? Could it be on it's way out?

[erice]

the boat is a 1989; pump does not look new. the hoses & connectors seem intact. would it make sense to install a diaphram kit?

[jleonard]

would it make sense to install a diaphram kit?

Perhaps, can't hurt.
However I once simply opened up an older pump and cleaned all the yuck out of it especially in the diaphragm area and it started working perfectly again.
Also might have a clogged up pressure switch??

[DougSea]

I'm wondering if there's a blockage downstream from the pump. Did you try running the pump without connecting the outlet side? Your description of air pressure coming from the faucet side would seem to indicate that the problem is past the pump. I'd try back feeding the system with a garden hose, see if anything flushes out backwards.

[erice]

well, i pulled the pump & checked the diaphrams and such. all lookes good. put it back together, still same concern. replaced pump, working like a champ now. thanks for the assistance.