1990 Suzuki Sidekick 8 valve engine - two days after my son had a minor fender bender the car will crank and not start.  Our shade tree mechanic says the fuel pump is getting power, has fuel, the code flashed as 12 which AutoZone said meant the computer was good.  The fuel pump doesn't not pump for 3 seconds when the key is turned on - only one second.  What makes fuel pump relay stop?  I asked him to check the voltage on both sides of the relay and he's trying that this morning...what are we overlooking? I've misplaced my FSM!

Check out Acks Faq, I believe he has an FSM for the 8 valve Tracker on-line.

Code 12 doesn't mean that the computer is good, it only means that there are no faults logged. I would start by checking the connections behind the tail light. I would also check the current flowing through the pump using a multimeter on the amps range. If there isn't enough current flowing then that indicates a poor connection somewhere, possibly at the connections on the top of the tank.
You didn't say which end of the Kick took a hit, could you have trapped/kinked the fuel return line - the pump will stall if the pressure in the line is excessive. Alternatively a blocked breather or fuel filter will cause fuel starvation.