330 Fresh Water problem?

Bayhouse

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2003 GW 330 Express.

Fresh water pump seems to only pressurize when the tank is completely full. I've filled it to overflow 3x today alone and have only used a little water for the head and to wash some dishes (Gauge shows no less than 3/4 full after a little use). I haven't dug around the bilge yet (my least favorite job) but have searched for air leaks around the pump/accumulator (all dry), head and sinks - no signs of problems.

Strange that it works fine when full, but won't pressurize (pump turns off) when I've consumed a little water.

I'll check the filters on the pumps tomorrow but I routinely add a little chlorine to my tank - not sure why clogged filters would work with a full tank but not less than full - and am out of ideas.

FYI, had a lack of pressure problem before, but it was consistent. Found a pinhole leak in the supply line to the head going through the aft bunk forward bilge. Original hose was tight against rough fiberglass (a real disappointment for a Grady).

Don't know if this is somehow related, but it also seems that the head will only pressurize when the fresh water does....Can't tell for sure and now that I've thought about it, can track over the next few days.

Any ideas about where to start?
 
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JoleGW33

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Your post is a little hard to follow. Not sure if you are taking about the head or the fresh water system..

Fresh water system pressurization has not much to do with how full your tank is as long as it has some water.

If you have a leak, you fresh water pump will cycle on and off in order to maintain pressure, so the easiest troubleshooting would be to let your system build pressure (run some water through the faucets and close them).. if you hear your pump cycling on and off then you have a leak somewhere.

Head uses fresh water to fill the bowl, so if you dont have fw pressure, it won't fill up.
 

Wannderer

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The hose runs from your tank straight to the accumulator tank. The balloon inside accumulator tanks could develop a pin sized hole/ just get worn out/ whatever. I have a 330 since new in 2004. Replaced the freshwater pump I think three times. First one or two lasted 10 years or so. Then I put a new one in at some point and the pump kept cycling on no matter how many times I tweaked the shut off switch. The pump gave out in about a year if I remember correctly. I put another pump on, same cycling. Called shurflo, I explained my situation and they suggested it was probably the accumulator tank due to age and symptoms. Replaced that and no more problems in the last 5 years. Also, when it comes to plumbing, the newer style shurflo baitmaster pumps works with the new accumulator. As in the fittings line up between the pump and tank when fastened into the wall.
 

Bayhouse

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My issue isn't with the FW pump cycling on/off, the whole system was not pressurizing and I was fairly certain there was a good amount of water in the tank. When I fill the tank, the system pressurizes and works fine. I was washing some things this week and had some air in the hot water side, both in the galley and head sinks. Since then, everything has been working fine....until I get low on water again.
 

wspitler

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The water gravity feeds to the inlet of the pump thru a fine screen filter. Wannderer said it goes to the accumulator first, but the accumulator is on the pressure side, downstream from the pump. Maybe the higher level in the tank allows it to gravity feed thru the filter, but when the level of the tank gets lower it doesn't have enough head to get thru the filter if it is even slightly clogged or corroded. Air in the lines on the pressure side will just act like another accumulator and unless the air gets to the pump, should not matter. I assume that when it is not pressurizing, the pump is running continuously. If not, then the pressure switch on the pump is bad. Easy to check the filter screen. Mine looks like this: https://www.wholesalemarine.com/water-system-strainer-79102.html?gclid=CjwKCAiAhJTyBRAvEiwAln2qBy0gH4CYPC8rz_Tzq6yofrxOGBxTRiJTYrET2vdBd88_i7t796KIixoC7T8QAvD_BwE
 

Bayhouse

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The water gravity feeds to the inlet of the pump thru a fine screen filter. Wannderer said it goes to the accumulator first, but the accumulator is on the pressure side, downstream from the pump. Maybe the higher level in the tank allows it to gravity feed thru the filter, but when the level of the tank gets lower it doesn't have enough head to get thru the filter if it is even slightly clogged or corroded.
I'm not following the 'gravity feed' idea, the FW tank is in the bilge and the outlet from the tank on the very bottom - it's an uphill ride to the pump.

Air in the lines on the pressure side will just act like another accumulator and unless the air gets to the pump, should not matter. I assume that when it is not pressurizing, the pump is running continuously. If not, then the pressure switch on the pump is bad. Easy to check the filter screen. Mine looks like this: https://www.wholesalemarine.com/water-system-strainer-79102.html?gclid=CjwKCAiAhJTyBRAvEiwAln2qBy0gH4CYPC8rz_Tzq6yofrxOGBxTRiJTYrET2vdBd88_i7t796KIixoC7T8QAvD_BwE
This idea sounded good....but I traced the FW supply line from tank to the pump and this is no filter. There is one on the RW wash down, but not FW.

Yes, the pump runs continuously when it doesn't pressurize. Add water, pump runs, pressurizes and then stops like designed.
 

Bayhouse

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Can anyone else with an older 330 confirm that there is no filter in their FW system?

The manual states it's either a 44 or 50 gallon tank. I timed how long it took to fill a bucket and compared that to how much water I needed too add to top off the tank - it took a little less than 6 gallons (probably what I use in a few flushes and dish washing). I think the rules out a leak.

The pump looks to be original (mfg in 2002)....
 
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wspitler

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I'm not following the 'gravity feed' idea, the FW tank is in the bilge and the outlet from the tank on the very bottom - it's an uphill ride to the pump.



This idea sounded good....but I traced the FW supply line from tank to the pump and this is no filter. There is one on the RW wash down, but not FW.

Yes, the pump runs continuously when it doesn't pressurize. Add water, pump runs, pressurizes and then stops like designed.
It may not have a filter, but my point was that water seeks it's highest level, so the water supplied to the pump will have the same pressure level as the highest level in the tank, regardless of where it exits the tank. The static pressure provided by gravity feed (head) to the pump may not be enough when the tank isn't "topped off." I know it's a stretch. but stranger things have happened. Think of it this way, if the entire tank (top of the water in the tank) was lower than the inlet to the pressure pump, the pump would have to suck it up from the tank. If the tank was 30 feet above the system, you wouldn't need a pump. Gravity would provide the pressure. Maybe, the lower tank level isn't overcoming some sort of obstruction in the feed to the pump. I would think there would be a screen of some sort between the tank and the pump, but maybe not. Might be worth investing in a new pump. Good Luck!
 

Bayhouse

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Got it, makes perfect sense. I disconnected the supply line to the pump today and had good/clean water from the tank. I'll have to undo the other connections next week to see if I can discover any blockage, then i'll try the new pump. Thanks for the help!
 

HMBJack

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It's a 17 year old boat (and pump possibly). Pumps aren't that expensive. You're on the right track...
 

DennisG01

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Often times, the filter is built into the pump. There are typically two styles - the first one is a round, clear, spin-off cap - you should readily see that and identify it as a filter. The other is a square, pop-up style (often black in color, with a blue button to release the screen).

Check the vent/vent line. If that is clogged, it could be causing an issue. An easy way to check that is to remove the fill cap. If the problem fixes itself, the vent line/fitting is the issue.

Another thing is the hot water heater - if the expansion valve is open, or leaking, that is letting pressure out. That's easy to verify by just looking at the valve - or the thru-hull overflow if Grady plumbed to a thru-hull (or just dumping into bilge?). Although that, one would think, would cause issues all the time, which is not the case here.
 

Bayhouse

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Related question, but doesn't the accumulator tank "tell" the pump that it's full causing the pump to stop? Trying to decide which I try to replace first (after trying some of the other ideas from Dennis).
 

DennisG01

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Related question, but doesn't the accumulator tank "tell" the pump that it's full causing the pump to stop?
Not really. The accumulator is not the issue, unless it's leaking outwards (leaking internally shouldn't affect anything as it basically just becomes an empty tank that gets filled up - essentially just another water line). But if it was leaking outwards, then the issue would be happening all the time, which it is not. The accumulator "buffers" the pressure/pump so the pump doesn't turn on/off as often/quickly when a short burst of water is required (quickly turning the faucet on/off).
 

Bayhouse

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Often times, the filter is built into the pump. There are typically two styles - the first one is a round, clear, spin-off cap - you should readily see that and identify it as a filter. The other is a square, pop-up style (often black in color, with a blue button to release the screen)..
I seem to recall seeing a blue button, I'll be checking that first.

Check the vent/vent line. If that is clogged, it could be causing an issue. An easy way to check that is to remove the fill cap. If the problem fixes itself, the vent line/fitting is the issue.
Don't think it's the vent, it's built into the fill line and I get air out when filling.

Another thing is the hot water heater - if the expansion valve is open, or leaking, that is letting pressure out. That's easy to verify by just looking at the valve - or the thru-hull overflow if Grady plumbed to a thru-hull (or just dumping into bilge?). Although that, one would think, would cause issues all the time, which is not the case here.
This has potential! Twice after filling, i've heard a strange noise from the area of the HW heater, that too is on my to-do list.

Great advice on this forum!
 

Bayhouse

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No luck finding a filter, I was mistaken about the blue button. New pump (and an in-line strainer) has been ordered, I'll post an update when installed.
 

Bayhouse

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Replaced the pump (and added a strainer) today, after getting my fittings right, the pump primed perfectly. Even better, the new pump is much quieter than the old. Ran the tank down and it held prime at each stop point. I'm back to 100% - thanks all for the help!
 

usmm1234

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Sorry I didn’t see this earlier. I’ve been the Shurflo Marine Rep for 31 years and I own a 330. Ive sold Grady their pumps since 1990. Obviously a strainer is an absolute requirement. In past years Grady used our Blaster pumps for everything. Hence the accumulator on the freshwater side. Now we make an Aqua King II that has a mechanical bypass built in to it. It delivers the required amount of water to the faucet or shower and recycles the rest of the pumped water back thru head. All the while maintaining 45psi. They still use the Pro Blaster on the washdown Side. You do not need the accumulator with the Aqua King II On the freshwater side. It should be removed. Both pumps should have our 50 mesh strainer screwed directly onto the inlet side of the pump.
Letme know if you have any questions.