We installed a Whirlpool WHELJ1 gold central water filtration system. The pump clicks on and off with the by pass open. When we turn the by pass off the pump runs normal. What would be the problem? We have a square D switch.

Hi Mary and welcome to The Plumbing Page on AMHD.
You piggybacked on a 2 year old dead thread so I gave you one of your own. Before you post look in the upper left hand corner for the date..
What's a "Whirlpool WHEL and what are you bypassing? Back to you, Tom