Grump,
Something had to cause the circuit breaker to pop.. I doubt it was the breaker itself..
As Allen points out, you need to test the voltage at the input and output of the timer.. If you have voltage at the input to the timer and no voltage at the output of the timer, then the problem is the timer.. If you have voltage at the output of the timer, then you need to test the voltage at the input to the pump. If you have voltage at the pump, and it is not running, then your pump is the problem.
Keep in mind that if your system runs off of 240 volts, you must test between the two input pins to see 240.. Testing each input pin to ground will not give you a valid reading..
Thanks,
Jim R.