I have a water pump, a Hitachi WT-P200G.

After having my water tank cleaned the pump was working fine. It did pump water in "waves" (like on off on off on off), but it was fine.

I just checked the tank and it is clean. However the pump is pumping water in smaller increments.

How does this work, and why? It is quite annoying to be under the shower and have lots of water, some, lots, some, lots etc.

Any solutions/suggestions?

Thanks!

Pump cycling like that is usually caused by the pressure tank being full of water, it's supposed to have an air space.

Check your pump handbook for how to re-fill the air reservoir. Failing that, there are a couple of threads with basic instructions, try a search.

Pump cycling like that is usually caused by the pressure tank being full of water, it's supposed to have an air space.

Check your pump handbook for how to re-fill the air reservoir. Failing that, there are a couple of threads with basic instructions, try a search.

Thanks, I did a search (should have done it immediately) and I think I found the answer. It's an oldie so probably the rubber flange (whatever you call it in english)

Thanks

Sure sounds like you have a booster tank air leak and/or the air has been absorbed into the water. That is, a water-logged pump tank (and I'm not talking a big/multi-hundred liter above/below ground water "storage" tank...but the "pressure" tank for your pump"). Keep in mind the pump's booster/pressure tank, although small, must maintain a certain amount of air in the top of the tank to act as a compressed spring to push water out when the pump is off. No/low air means the pump will "short cycle" by turning off and on a lot...every second or two. Water/liquid can be compressed very little to create a spring; air is very compressible which creates a spring to push water to your water system while the pump is off and taking a rest. This constant on and off of the pump will cause the water from your taps/showers to "pulsate" quite a lot...and you can also hear this pulsating when your commodes refill.

First, turn off power to the pump. Second, be sure all pump screw-on caps/connectors, screws, & bolts are tight...especially those of the pump manifold assembly. Third, if you have pump water inlet and outlet cutoff switches, close these switches to isolate the pump. Fourth, "completely, repeat, completely" drain the pump tank...there should be a drain valve on the side very near the bottom....when the water "completely" drains it will allow air to rush into the tank and properly recharge the tank with air. Fifth, close the drain valve. Sixth, reopen the water inlet and outlet valves. Sixth, turn on power to the pump. If I left out some steps I think you get the general idea.

Check to see if the pulsating water from the taps is now gone. Hopefully it is. Turn on a nearby tap full blast/stream and then count the number of seconds between the pump's turn on and turn off...hopefully it's somewhere around 3-6 seconds....this will be your reference to check for an air leak a few days/weeks later. Now, over the next few days/weeks run this check again to see if the pump on/off cycle is still around 3-6 seconds; if not you have an air leak which is allowing the tank air which is providing that "spring" to push water out to leak off. Even with no air leak, the air will eventually be "absorbed" into the water and require you to drain/recharge the tank with air....I don't know how long this takes but it should be months at a minimum.

Above info based on my experience with my Mitsubishi WT-255 which is basically a pump motor setting on top of a small water/air tank which I think is basically the same type water pump that you have. Good luck.