I have a 370 express. I just put a new fresh water pump in and my hot and cold water serges in my shower. the pump is a shur flow and has 3.5 gpm. this is a problem. Does abyone have an answer? My old pump was a shur flow 3.0 gpm.
fresh water pump serging
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Alegria
Well-Known Member
I believe its the pressure switch setting on the pump if your is adjustable. There would be a screw in the center of the pressure switch. The 4900 series seems to have one the 3900 does not.
Here is a link to their web site of the PDF for the non variable speed. They mention adjustment of the pressure switch on page 4
http://www.shurflo.com/pdf/Marine/911_trouble_shooting/911-740-D.pdf
If you have the 4900 you might be able to adjust the pressure switch setting up a bit. I would suspect that the pulsing is the pressure building to a point right at cut off then dropping because the faucet is open causing the pump to turn on again.
Since you did not have any problems before and you did not mention that you had air in the system I would suspect the pump.
Also could be losing the vacuum on the supply side. You can tell by watching the pump as its running, if you see air bubbles coming into the inlet filter then its not pulling a vacuum and that could cause what you are seeing too.
If neither, then its the pump, I would take it back.
Best of luck!!
Here is a link to their web site of the PDF for the non variable speed. They mention adjustment of the pressure switch on page 4
http://www.shurflo.com/pdf/Marine/911_trouble_shooting/911-740-D.pdf
If you have the 4900 you might be able to adjust the pressure switch setting up a bit. I would suspect that the pulsing is the pressure building to a point right at cut off then dropping because the faucet is open causing the pump to turn on again.
Since you did not have any problems before and you did not mention that you had air in the system I would suspect the pump.
Also could be losing the vacuum on the supply side. You can tell by watching the pump as its running, if you see air bubbles coming into the inlet filter then its not pulling a vacuum and that could cause what you are seeing too.
If neither, then its the pump, I would take it back.
Best of luck!!
