Sump pump started running constantly

[D & C]

Please help...We live in a basement condo about 200 yards from Lake Michigan. Since we moved in 2 years ago we have had several instances were our sump pumps runs continuously. It is not weather related, we suspect something wrong with the pump. The builder that refurbished the building lives upstairs and has sent someone over to correct the problem in the past, I think it has even been replaced. My question is whether it sounds like something major is wrong with anything beyond the sump pump or if we should simply get a different plumber to look at it. During periods of continuous running, dirty water (Sewage I think) has backed up into our showers and a drain in a kitchen utility closet and the toilets gurgle when we run the washing machine and dishwasher at the same time. I hope to have a better idea of the possible problem and sump pump function before having a plumber come in. ANY FEEDBACK???

[Deb]

I would venture a guess that either: the pump is not working and sewage in not being pumped out. Pumps usually do not work intermittantly, but floats can get caught and cause the pump to run continually, but sewage is pumped when this happens so this is an unlikely cause. Or the volume of sewage that is being put into the sump is too much for the pump to handle--it is running continuously, but sewage is not being ejected as fast as it is coming in. Or maybe a partial clogged drainage line clog could cause this too--not pumping out as fast as it is inflowing. If you are getting sewage into your unit when you are not using fixtures, this is most likely in a main line somewhere and may actually not be your responsibility alone, you could just be the one feeling the (nasty) effects. There should be a check valve to keep other sewage out, but these can fail or sometimes they are not there.
Deb
The Pipewench