[Zed]

Infrequent poster, long time lurker.

I have a relatively new to me Pearson 303 (86). The PO replaced the the old fresh water tank with a 30 gallon bladder. The system has an electric pump with an accumulator to pressurize the system. It works great till the bladder gets down to between 1/3 and 1/2 full. Then the pump will not fully pressurize the system, it will just run till I flip the breaker off. Eventually the water will stop flowing even if I have the pump on and there is still water in the bladder. If I top the water off it works fine again. I would think I should be able to get more water out of the bladder before it has trouble pressurizing the system.

Am I mistaken? If not what could be the problem?

 

[IStream]

Sounds like the pump is pulling air when the bladder gets down. Make sure the pump pickup tube is at the lowest point of the bladder. If not, try to reorient the bladder to make it so.

 

[Faster]

Yes.. sounds like the bladder wall is closing off the intake as the bladder settles/collapses.

 

[RichH]

Increase / readjust the pressure in the accumulator ... back to 'spec'. There should be a Shrader Valve (looks like an automotive tire air fill valve) on the accumulator - attach a bicycle pump and get the pressure back to spec.; ............ then, check for leaks, faulty pump valves, bad pressure switch on the pump, etc.
First Step is to verify the air pressure in the 'accumulator'.

 

[capta]

I'd be inclined to blame the vent line. Most water pumps don't have much suction power, they're designed to push the water. If the vent gets plugged they just don't have the power to deflate a bladder tank.

 

[Stu Jackson]

I'd be inclined to blame the vent line. Most water pumps don't have much suction power, they're designed to push the water. If the vent gets plugged they just don't have the power to deflate a bladder tank.

I agree, My first question is do you even have a vent, since you said the PO put it in. Never know what a PO can do. Although it'd be impossible to fill without one.

 

[IStream]

A vent is good for any tank but you don't need a vent to drain a bladder, it just collapses instead of supporting a vacuum like a rigid tank. You can get away without a vent to fill a bladder if the fill tube is big enough in diameter that the water coming in doesn't completely fill the tube cross-section.

 

[Delta-T]

One last thought, what is the location of the tank and how far below the pump it is the tank? The pumps have a lift rating on the suction side, it may only be 3'.

 

[Zed]

I think pickup is under water so to speak, so it should have water and not air, but I will make sure.

I want to say the is a vent line, but honestly, my memory is being a bit hazy, so I will check that too.

The bladder is near the same level as the oump, no more than a foot difference, but they are on different sides of the boat, so I will check to see how the lines are run.

I also noticed that the bladder had a lot of air in it,, which didn't seem right to me. I vented what I could out a plug in the top of the badder. Didn't help, but might have air in the system now. (Hindsight)

 

[deniseO30]

Zed let' s see if the pump has a good impeller? If water is bypassing around it would not work well