Sudden fresh water pumping issues

[NYSail]

Hello all,
So a couple of weeks ago my back tank all of a sudden started having priming issues when I switch tanks eventually would grab. Never an issue before. Now the front tank is doing the same. Once it’s primed no issue and pump lines seem to be holding pressure fine as pump does not continue to run. I tightened all fittings just to be sure. Pump is 2 years old Johnson 3.5 gallon/minute. O e thing with the setup I have never liked was the strainer…… gathers air at the top……. Would think it should be different to get all air out. Any suggestions s what could be causing this?

thanks
Greg

 

[kloudie1]

Gathering air in the strainer indicates an air leak. That would cause the loss of prime in the pump. Suspect the strainer bowl gasket and any fittings prior to the pump. A bad selector valve packing or seat too.

 

[Captain Larry-DH]

Maybe a tiny vacuum break on the uptake side, that allows air in but small enough to hold prime? Or, maybe some crud on the intake valve inside the pump that's not allowing a perfect valve seal? I'd look at the strainer housing and gasket as a possible source, too.

 

[NYSail]

Just to add also I did make sure the vents are clear…..

 

[NYSail]

The pump will pull air when the tank runs dry. He problem with that style strainer it holds the air and never fills with water…… just the bottom.

 

[Bob S]

I had a similar problem where I could not get the aft tank to prime. I had no problem with the forward tank. I am guessing once you have it primed it doesn't continually cycle. I replaced the pump and haven't had a problem since. The forward tank on my 393 is above or at least parallel with the pump but the aft tank is below. I figured the impeller was worn to the point it could prime the aft tank but functioned ok with the forward one.
I would try rebuilding or replacing the pump.

 

[Captain Larry-DH]

I had a similar problem where I could not get the aft tank to prime. I had no problem with the forward tank. I am guessing once you have it primed it doesn't continually cycle. I replaced the pump and haven't had a problem since. The forward tank on my 393 is above or at least parallel with the pump but the aft tank is below. I figured the impeller was worn to the point it could prime the aft tank but functioned ok with the forward one.
I would try rebuilding or replacing the pump.

This is why I started to standardize on WM-branded aftermarket pumps. Not that they're any better or worse than others (at last look they were made by Johnson Pumps) but you can take a failed 2-year-old WM pump into any store and walk out with a new one.

 

[JamesG161]

I have never liked was the strainer

I love mine. It is a great "sight glass" to verify flow.

By the way..
That trapped air will slowly be absorbed by the water, if no leaks in the suction side of pump.
Jim...

PS: Your strainer has the best orientation.

 

[Tally Ho]

PS: Your strainer has the best orientation.

Jim, why an upside orientation?

I have one similar, but I think it is oriented the other way…

Greg

 

[JamesG161]

Jim, why an upside orientation?

I looked at his picture and thought the strainer was pointed upward.

the strainer…… gathers air at the top

To me it should be oriented as a...

Bubble Trap

Or the clear top up.

But even side ways it would still trap any air.

The strainer should be on the suction side of his pump. I can not see where it is connected to the suction side.
Jim...

 

[NYSail]

It was the pump…… fortunately when I replaced the original pump (not broke just because) I kept it on the boat. After checking all pre-pump fittings as well as cleaning and reinstalling the strainer, the pump was last chance.
All good….. thanks for the advise guys!

would have put a damper on the trip…….

Greg