Greetings and forgive me for the verbosity. Just trying to save questions. 1984 56MY. I ran the tanks dry when i forgot to turn off ice maker after shutting off dock water. 2 weeks later when we returned, the 110V FW pump was running dry but it did not seem to be damaged. I turned on the dock water and there was a slight fitting leak in the housing, which i repaired with thread compound.

When I attempted to refill water tanks, water came out of the vent lines after about 15 minutes of filling with dock hose. It should have taken an hour or so and i wasn't sure what was going on. I did notice that F/W was dripping out of both vent line fittings and water fill opening when connected to dock water but not consistently. I left the 110V FW pump valved off and circuit off as well. When we left for the weekend, i shut off the dock water and turned off the ice maker.

When we returned a week later, I turned on the dock water and noticed that the boat water pressure was very low. I turned on the 110V F/W pump and it never made enough pressure to make the pressure switch. There was water gushing out of the vent lines and water fill, so I turned the dock water down to a trickle just for the toilet. The next morning, i turned the dock water back to 100% and tapped all the check valves to see if they were stuck, but the big "AHA" was when i noticed that the isolating valve for the 32V F/W pump was open, allowing water to back feed into the tanks. Not sure why it was open, but when i closed it, everything went back to normal. Good water pressure, no more water coming out of the vents or fill. Thought i dodged a bullet.

Problem is that i noticed water coming out of both vent lines on Saturday and when i opened the fill cap, there was a lot of pressure that was released with about gallon or 2 of water. obviously, the tanks are being pressurized by the dock water somehow. Bad check? Something else? Any input or suggestions would be greatly appreciated.

thank you in advance.

Rich Carlini