Water pressure problems on new boat

hump180 · September 09, 2008, 08:18:28 PM

Hello everyone. I am working through the problem list of our 1990 that we recently purchased. The most recent problem is with the water pressure. When I turn on the water pump it runs but I only get foam from the faucets. The water tank is full and I do not see any obvious leaks and also the strainer is clean.
Also, I think I can see some air traveling through the lines. Does anyone have any suggestions?? Bad Pump?? Air leak??

Steve S. · September 09, 2008, 08:37:21 PM

Hey Hump - I had the same problem when I replaced my water pump. The problem turned out to be air in the input line and the pump just couldn't seem to produce enough vacuum to overcome it. So, I took off the input line and made sure it was full of water before I re-attached it. Worked ever since.

hump180 · September 09, 2008, 08:45:19 PM

I forgot to mention that the pump runs continuously when the switch is on. I assume that there is not enough pressure for the pump to switch off.

Sundance · September 10, 2008, 04:28:23 AM

Are the valves below the sink in the open position? Seems obvious, but I have to get under the sink and look to see if the valve is open or closed. I also had a smiler problem, I put a new strainer on and tightended all hose clamps and it has worked well for two years. The air was getting in the system at the strainer.

arthur · September 10, 2008, 02:39:41 PM

You say your pump runs continuously. I had that problem too this summer. I finally discovered when I shut off both of my inlet valves to my fore and aft tanks, the pump quit running. I needed a new check valve. Will, the check valve is part of the pump and one has to buy the entire pump to get the check valve (about $75.00). I bought a new pump which came with instructions on how to attach to my existing electric motor. All is working fine now.

I also get foam, but only when a tank is empty. To correct this I only draw from one tank at a time and just switch tanks. I have to turn faucet on and off to get flow going again.

Stu Jackson · September 10, 2008, 04:02:27 PM

An empty tank connected to a full one will drain the aft tank, say, into the starboard tank, and air will come in. Do as arthur suggested and valve the empty one off, one valve open at a time, never a problem with the pump or air.

hump180 · September 10, 2008, 04:33:13 PM

Thanks guys, I just came home from fixing the problem. I did have both valves open and closed one as you guys had suggested, the motor almost instantly pressurized and shut off and the water finally started flowing smoothly. Another problem bites the dust. My next post will probably be related to the crappy shower sump pump and bad location of the shower drain, but I will search the board for a while before I post any questions. Thanks again everyone.

waterdog · September 11, 2008, 10:50:33 AM

Quote from: hump180 on September 10, 2008, 04:33:13 PM
Thanks guys, I just came home from fixing the problem. I did have both valves open and closed one as you guys had suggested, the motor almost instantly pressurized and shut off and the water finally started flowing smoothly. Another problem bites the dust. My next post will probably be related to the crappy shower sump pump and bad location of the shower drain, but I will search the board for a while before I post any questions. Thanks again everyone.

It never occured to me that we had a crappy shower sump and bad drain location. After a shower on Blackdragon you can hear a cry of "starboard!" and everyone moves to the starboard side with the dog happily following and the shower drains nicely. We never thought of fixing it. However, I'm not a fan of all the moisture in the head anyway, so we installed a cockpit shower mounted port side under the seat next to the companionway. It's an excellent upgrade. I must post a photo.

Ken Juul · September 11, 2008, 11:58:48 AM

I thought the port list was to keep the water from running over the sill

To help motivate the water toward the drain we have a small window washing type squeege that we use to drag the water to the drain lines. Then the pump sucks it right out.

I'm sure your search will find that the two biggest problems with the shower drain are getting plugged up because of the poor screen or the anti siphon valve not working properly. Might want to disconnect the drain line at the pump and use a water hose to pressure clean the drain line. Check the pump inlet for debris before you hook the drain back up. The pumps are pretty robust, don't hear of them failing often. I think it was Ron Hill that suggested using a piece of "scotch bright" as a filter in the floor outlet to keep the drain line clear.

hump180 · September 11, 2008, 12:26:12 PM

I will clean the line today with a hose as the last time I ran it the hose collapsed on itself. I assume there is a clog causing the suction build up and in the future I might try the scotch bright filter idea to prevent this.

Stu Jackson · September 11, 2008, 12:53:17 PM

The "filter" Ron suggested is a piece of plastic insect screen material gently daubed in place with some silicone as a disposable filter screen. We have the old style flat ShurFlo check valve, which can relatively easily be disassembled, cleaned and replaced. A bit of PB Blaster on the nuts. Be careful taking it apart, since you'll want to put it back together the same way. It's a 1/2 inch hose barb on a 3/4 inch line, cleverly put together by the factory with some additional hose material in between to keep it tight under the hose clamps. The pump is a diaphragm pump which should easily last for years and years. Use some fresh water and clean out the sump. Earlier Tech Notes discussed cutting the cabin sole underneath the teak and holly to get to the sump.