It sounds to me as if the motor has a thermal safety
switch on it, or a self resetting breaker. Something
may be binding and the motor overheats. These types
of washers are not to be run for very long without
actually 'spraying', or the pump overheats, due to the
fact the flow of water is also used as lubrication and
cooling. If the pump is run for very long without
water flowing through it a great deal of heat develops
and damages the pump. Your pump may be the problem.