Groco Transfer Pump Reversed?

[Desssertfirst]

Good morning Cruisers- Brain teaser for your morning. Aboard my Chatham Extrem 50, I have two diesel tanks. One is a slave, the other the source, with a Groco SPO-60-N 12v (Not the reversible unit) in line to move fuel from one to the other. The boat was in the yard for 6 months and now that she is back in the water, the pump seems to be pumping in reverse. The sound of bubbling air in the slave tank, air releasing at the vents, and no movement in the gauges after running for 25 minutes. My contractor says they DID NOT touch the pump or it’s wiring. Has anyone experienced this and how did you solve? Thanks in advance.

[tkeithlu]

You've presented pretty good evidence of the pump pumping backwards; it pumps backwards.

My suggestion is that you simply disconnect the wiring at the pump and, with your multimeter, determine the orientation of the 12v DC with the switch on. That is not meant to assign blame for it being backwards, but gives you the starting point for tracking down where the circuit was reversed.

[Desssertfirst]

Thank you tkeothlu. I’ve tracked the wiring (it is well marked) and nothing changed from the days when it worked in the correct direction. My contractor suggests that it may be the impeller. Does that ring true to you? That said, I will break out my multimeter when in the boat this afternoon.

[tkeithlu]

Have you tried simply reversing the wires at the pump? If it's orientation that is creating the problem, that should show it.

If that isn't it, let's think about something in the sceanario being wrong. Is the pump itself mounted the usual way, or could it have been flipped?

It's possible to put an impeller in with the vanes tipped over the wrong way, but that should either straighten out on the first rotation or tear up the impeller.

Any progress to report? Either success, or more information to consider?

[stormalong]

Originally Posted by tkeithlu

Have you tried simply reversing the wires at the pump? If it's orientation that is creating the problem, that should show it.

If that isn't it, let's think about something in the sceanario being wrong. Is the pump itself mounted the usual way, or could it have been flipped?

It's possible to put an impeller in with the vanes tipped over the wrong way, but that should either straighten out on the first rotation or tear up the impeller.

Any progress to report? Either success, or more information to consider?

This is not an impeller pump in the sense of an engine water pump">raw water pump. It is individual vanes on a slotted hub. They cannot be "inverted" or installed backwards.

I have one of these that was sold as a deckwash pump and found it to be a poor pump for water. It might be more suitable for a self lubricating fluid like diesel fuel or lubricating oil.

My guess is that the vanes are worn to the point where it will not pull a prime. They do sell rebuild kits for these.

PS. I tried to edit the first sentence of my response to remove the extraneous words and quote mark but it will not change. Weird.

[tkeithlu]

Thanks for speaking up, Stormalong. That helps make sense out of the situation.

[Searles]

A sliding vane pump with worn vanes may at times cavitate,it will drag air but not heavier liquids .just maybe, change wireing for rotation ,just maybe .⚓️��⛵️

[Desssertfirst]

Problem Solved! Yes, my contractor said that they “did not touch the wiring connection at the pump” but upon following TKIethlu suggestion, testing the wiring...I found the wires were reversed. Thanks to all for your contribution. My transfer pump went from blowing bubbles to moving fuel.