Fresh water pump

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Gregory S

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Today while using the fresh water system, the pressure started out good and the demand pump (Sureflow 40 psi) was running continuously as usual when a tap is open. Then the pressure dropped and the pump began to cycle on and off continuously. Is this a worn out pump, bad pressure switch or a problem with the accumulator tank? I saw a lot of crud in the filter before the pump, cleaned it out and no change.
 
i don't think it can be the accumulator tank, there isnt' much to it.

it coudl be crud past the filter and stuck in one of the little check valve in the pump. happened to mine, a shurflow electronic a year ago. opened it up and found a piece of plastic stuck in one of the pistons checkvalves.
 
Thanks Pascal, guess I'll be tearing into the pump. The filter sure had a lot of crud in it.
 
Could be the pump's check valve has dirt in it and water is backing up into your tank, dropping the pressure and causing the pump to come on - then it comes up to pressure, shuts off, leaky check valve causes the water to bleed back, the pressure drops and pump comes back on. On and on, far off into the night...
 
That's what it's doing Vic. Is it poosible to take the pump apart and fix it or is it best to buy a new pump? It only cycles like this when a tap is open. Starts out fine then after a minute or so, it starts to cycle on and off.
 
If it only does it while a tap is open, that's a different kettle of fish. The pump is coming up to pressure and shutting off, faster than the water is being used. Open the tap more so that it is going full-stream. Otherwise, you'll need to add an accumulator tank to the system, to smooth out the flow.
 
Thanks Vic, happens with tap(s) wide open. I have an accumulator tank in the system already. that's why I was thinking the pump or the pressure switch is bad. I've already cleane the filter out that sits in line just before the pump so i don't think there is an obstruction to in flow.
 
you shoudl be able to take the pump apart and clean the valves... not sure how yours is put together but on the large shurflo, it just a few screws to pop the cover and a few more to get the diaphragm out and clean everything.

if that doesn't fix it, then it could be the pump motor itself getting tired and loosing power as it hears up, since you say it happens after a minute or so.

you can easily eliminate the pressure switch as a cause, by opening a faucet and bypassing the switch (pull the wires and conenct them). watch what happens to the pressure at the faucet... if it remains the same, then you know it's the switch... if it drops after a while, it's the pump.
 
also clean the faucet aerators. sometimes they will get clogged, and restrict the flow.
 
Agree with Gary; check the faucets before you tear into the plumbing.
 
Thanks guys. I'll clean the faucets first then look into the pump.
 
Well, the aerators on all the faucets were clean. I hooked the water hose up to the the city water inlet and had very little pressure at any tap. I figured this meant an obstruction to flow somewhere. Then I remembered I hadn't checked the big added on filter. When I removed the cartridge, I couldn't believe how clogged it was. Switched the fresh water pump on with the cartridge out and the pump worked fine. No more rapid cycling.
 
Greg I am curious what tpe of filter are you using? The one that got clogged. Thanks Bill
 
This is an add on filter in line like you would put under your kitchen sink. The cartridge was so clogged, I couldn'nt push any air through it! I don't know how the FW pump was pushing the water through that was getting through. Must be pretty strong pumps.
 
Greg,
Glad to see that it was a simple fix. I also use a charcoal filter mounted on my shore power post outside the boat. Our marina has pvc plastic pipe for supply lines, and the glue that is used seems to plug up the little strainer on the suction side of the water pump very quickly.
The charcoal filter catches any dirt and sediment before it gets to the boat. saves alot of work.
 
Thanks Gary,gotta love it when it's a simple fix. There is only 1 component on my boat that's tough to get to. Yup, the Fw PUMP! Glad I didn't have to R/R.
 
glad it was just the filter... i'm starting to hate that POS shurflo... first one lasted a year, replacement from shurflow is 3 months old and last night... no water. pump not running. i go check in the ER and find the pump burning hot. apparently the press switch is acting up causing the pump to keep pumping... I have a gauge on the acc tnak and pressure was over 90psi... going to connect an old raritan press switch i have on that tank...
 
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