I have had a grundfos mq3-45 1hp booster pump installed under my house for about two years now,(reason for this is my well is 500 some feet away from the house and at the bottom of the hill ,and my well is 400ft deep) anyways ive never had a problem til a week ago, my grundfos pump would turn on and off while taking a shower thus making the pressure go up and down. I called the company and they said for me to check my pressure tank and make sure its still between 22-24psi, so i climbed under there and when i went to put a pressure gauge on the end it started spitting water, so i called the company back and they said it was the pressure tank(lil oil filter looking thing that only holds 5oz of water) and mind u cost me 117 bucks , so i screwed this new pressure tank thing on and its STILL NOT working correct, i turn on the faucet and the pump will wait about 40 seconds to kick on and then run for about 12 seconds and turn back off and so on, all the while the faucets open. Like i said i have never had a problem with it before this so im baffled and of course i had to do this on a fri night so now i cant talk to anyone at the company til monday, so does anyone have any input ? I took the new part off and put the old one back on since it didnt seem to matter,and im hoping they might take this lil piece of crap back if i decide to just junk this pump. Any suggestions or ideas ? Thanks