Intermittent ballast pumps - fast fill

[Jacrews]

2018 Xstar. I noticed that my starboard ballast wasn’t filling nearly as fast and sounded quiet. I popped the hatch and noticed that the top starboard ballast pump was running, but not the bottom. After the pumps turned off, I did a manual empty and the bottom starboard pump turned on. After that stopped (30 sec), I did another manual empty because the bag still had water in it. Both starboard pumps ran this time…. Another bit of info: my batteries are original and I was planning on replacing them in spring. Last weekend I got a “starting battery low, start boat to recharge” or something similar. From what I understand (if I recall correctly), the ballast pumps pull from the alternator and the battery. Could this be the issue, or do you suspect something else? No breakers are tripping, and the impellers were replaced 25 hours ago.

[jpwhit]

Sounds like the run-dry protection circuit that's built into the Johnson 30 GPH pump is tripping. I've never had the need to dig into one of those pumps to see how the run-dry protection works, but I always assumed its temperature based. Those pumps need a lot of water moving through them to stay cool. I guess in theory the issue could be as simple as the impeller needs to be replaced because the old one isn't drawing enough water through the pump. But for that to be the case, the impeller would need to be intact enough to load the pump, but at the same time does not move enough water to keep the pump cool. A lot of time when impellers are worn out, they also don't put a lot of load on the pump motor. In that case they don't typically overheat.

I would start by pulling all the impellers w/o mixing up which impeller goes with which pump. Then you can compare the conditions of the impellers and you can also reach in and feel how easily the motor shaft turns. The issue could also be that water has gotten into the motor bearing and they are dragging. That'll definitely cause the pump to overheat. That wouldn't happen as much if MasterCraft mounted the pumps as Johnson recommends with the motor up and the pump housing facing down.

[tchur1]

Check the relays for the pumps. I had a similar issue on mine last season where they would intermittently work and not work. Hit either fill/drain (depending on tank level) and tap the relay connected to those pumps, they get stuck and when you tap them with a wrench it can free them and they start working. I ended up just replaced the relays on both port and starboard sides because they are cheap and my pumps have all run great since.