98 350 Mariner - Fresh Water plumbing issue

[grizer]

Hello, when I run any faucet in the boat, it spits and spurt for a minute or two or sometime much longer until I get a nice stream. It does this whether I am connected to fresh water "hose" bib or have water in the fresh water tank or both. It seems to be much (MUCH) worse if NOT connected to a water source (ie., hose bib). Any suggestions on where to look? The screens on my faucets and coming into the boat are clean and my water source is nice city water. Do the 2 sources T-in together so that all of those faucets, shower and toilet work regardless of which or both are sourcing the fresh water? HELP!

[Midnightsun]

In a nutshell, the city water and pump water are on the same circuit. The city water is simply tee'd in like you say. Odd that it is spurting. Only time this happens to me is when I connect city water to the boat with a hose that is full of air, basically I am the one who introduced it into the system. I have quick disconnects on my city water hose so it now remains full of water which eliminates that. Never had any spurting when on the pump.

Only thing I can think of is the water is flowing back into the lines and filling somewhat with air. My best guess would be the water pump check valve.

Need a little more info on when it does it.

[grizer]

It does it every time I turn on a faucet...could have been on just 10 mins earlier, still spits

[Midnightsun]

Source of the post It does it every time I turn on a faucet...could have been on just 10 mins earlier, still spits

Same scenario when connected to city water or is it less evident? Do you turn off the water pump when using city water?

[km1125]

Sometimes it takes a bit to get out all the air pockets that get trapped in an accumulator or hot water tank. What I do is let the system get to pressure, then run the faucets at full flow, starting with the ones closest to the tank. Then, shut OFF the water supply (at the dock) and the pump and turn the faucets all on again until there is hardly any pressure... then turn on the dock and/or water pump, let it flow for a little bit, then turn the faucets off.

If you still have air spitting out, then I'd do a chlorine flush on the system in case you have something "growning" in the pipes somewhere.

[mjk1040]

Just a theory, but could both or one of the check valves in the system be bad allowing for back flow?
The shore water connection has a pressure regulator & a check valve built into it, it may need replacing?
The 12 volt fresh water pump has a check valve in its system too, otherwise when you were on shore water supply your fresh water tank would be over flowing! Do you have an accumulator tank in your system or bladder tank?

[grizer]

Interesting comments. Now i have literally no water pressure just a slow trickle although i hear and can see the pump running. Perhaps the pump is shot. Strange that only a week ago it ran very well and i had great pressure.

[grizer]

No I dont turn off the water pump when on city water, arent both water sources run by the boats pump? My pump runs whether on city or tank water. I feel like a previous owner may have redone plumbing and boogered something up somewhere.

[Midnightsun]

If you do not turn off the pump you will empty the tank and introduce air into the system since it is now pumping air and this will happen even if connected to city water! This is your problem! Just turn off the pump breaker in your DC panel each time you connect to city water. When you need water away from the dock, turn on the pump until you connect back up to city water. I like those easy ones like this, cost effective also.

City water is pressurized and does not need a pump to function whereas the potable water tank does need the pump since it is static.

[ronmar]

Should not need pressure pump when using city water. No need to run pump as it could burn up impeller. When on city water there is a check valve that closes so water not able to fill the freshwater tank and does not pull from it either. Tank can only be filled from the fill tube on outside of boat. The pressure from the hose bib will be all that is needed when on city water. When on freshwater tank then you need to turn on pressure pump. After pressurized will turn itself off. Will come back on when pressure gets low or when running water continuasly.
As to the spitting when using the freshwater tank, that will usually happen when switching to and from City water, or after filling, as well as not waiting until hot water tank completely fills as it also needs air purged. After filling and pressurizing you need to run cold water and hot water in all sinks to purge air. If happening every time using freshwater tank then more than likely there is a leak somewhere and or vent clogged not tank to vent properly. Also a possibility pump has a bad impeller and needs replaced.