Suzuki Repair: 93 Suzuki Sidekick Dead, engine cranks, suzuki sidekick

Question
My son's '93 Sidekick has died. It been with a mechanic for 3 weeks and he's given up. It died on the highway like it ran out of gas but a jump got him started again just long enough to get him home. The engine cranks but no gas, no gas odor (there's plenty in the tank, BTW). Starter spray runs the engine but it stops running when you stop spraying. Gas tank was dropped to check fuel pump but it's ok. Gas lines and injectors are free of obstructions. When the key is turned there's a constant, rapid snapping sound from a relay under the dash as well as some sensors (?) under the hood on the engine block. The fuses are ok (unless I missed one). My son said a friend used the Suzuki to jump start his car and might have botched the job by leaving the cables on too long. The car ran ok the next day but developed the trouble very soon after. Could the computer chip be fried or any other ideas?

Answer
It's possible the circuit that "fires" the injector is bad.  It's the one failure that occurs in the ecm.  Check to see if the injector is powered.  Then see if the ecm is completing the circuit to ground.  A dirty/corroded battery terminal can be responsible for this kind of problem due to poor grounding of the ecm.