AS SOON AS YOU GET THE OBVIOUS THINGS CHECKED OUT LET US KNOW WHAT YOU FIND , DO LISTEN FOR THE PMP TO CYCLE WITH KEY ,COULD BE RELAY, FUEL PUMP, OR THE ECM,OIL PRESSURE SW (DUAL ACTION) BUT TO ANSWER YOUR FIRST QUESTION, NO ISUZU DOES NOT USE ANY TYPE OF ENERTIA CUTOFF SW FOR THE FUEL PUMP CONTROL JERRY