Faster is absolutely correct the impeller will run dry for a short period. Even if it is downhill from the strainer to the pump and that section of hose is full of water, the air in the empty strainer will get sucked through the impeller.Are you saying the strainer is after the impeller? If the impeller is (properly) downstream of the strainer then it's pulling air for a bit until the system is once again flooded...
That impeller is going to have a very short life and failure will be sudden. When an impeller fails you have a few minutes at most to notice the overheat and shut her down or serious damage will occur.