Chevrolet Repair: vehicle shutting down for no reason, spark plug wire, chevy express

Question
2004 chevy express 2500 4.8liter engine    have replaced fuel pump and computer heat sensor and fuel pump relays   van may run fine 1-3 days then just dies while driving or idling.  can start van in yard may run a couple minutes then stall and wont restart. i wait awhile then can start right up and run one hour or two days fine then it happens again.   thanks,jeff

Answer
HI JEFF, WELL THE FIRST THING YOU NEED TO DO IS DIAGNOSE IF THERE IS FUEL TO THE FUEL INJ RAIL OR IS THERE SPARK TO THE SPARK PLUGS..ONCE YOU KNOW THIS YOU WILL BE ABLE TO LOOK INTO THIS PORTION OF IT..WITHOUT KNOWING THIS IT IS TRULY A GUESS...SO WHEN THIS HAPPENS PULL A SPARK PLUG WIRE OFF A PLUG AND INSERT A SCREW DRIVER INTO THE END OF THE WIRE AND KEEP THE SCREW DRIVER ABOUT 1/4 INCH FROM A METAL OBJECT..NOW CRANK THE ENG OVER AND SEE IF YOU SEE ANY SPARK, IF THERE IS THEN YOU CAN ASSUME THE IGNITION SYSTEM IS GOOD. IF NOT MAY HAVE BAD MODULE OR BAD CRANK SENSOR..WE WILL GET TO THAT AFTER YOU FIND WHAT IS GOING ON..SO LETS SAY THERE IS SPARK THEN I WOULD HAVE TO SUSPECT NO FUEL....ON TOP OF THE INTAKE YOU WILL FIND AND A TEST PORT[LOOKS LIKE A TIRE VALVE STEM CAP,] REMOVE THE CAP AND WHILE YOU CRANK THE ENG OVER PUSH DOWN THE CK VALVE AND YOU SHOULD HAVE FUEL COMING OUT OF THIS VALVE THE ENTIRE TIME YOU ARE CRANKING THE ENG OVER,NOT JUST THE FIRST SECOND OR SO.THE ENTIRE TIME THE ENG CRANKS..CK THIS OUT AND GET BACK TO ME ON WHAT YOU FIND...TOM