Lift the float switch manually and see where it kicks in.....as soon as it gets close to level it should start....it depends on the exact position of the float...is it centered and how low in the hull is it? from what I have seen in the front bilge, the pump is put in forward of the bulkhead drain so you can reach it fairly easily...if anything is plugging your drain, water is going to build up in that area before it reaches the float height and may seem like the switch isn't doing its job.