GMC Repair: 96 GMC 1500 with 305 wont start, cpfi, gmc 1500

Question
Do I have an injector problem? My trouble started about 2 months ago with just being hard to start. It would take a couple of turn-over sequences before it would start. The first thing I considered was water in the gas. I filled the tank with premium unleaded and treated it with HEET to help pass the water. I ran that tank until just above empty before I fueled again and included a bottle of fuel injector cleaner. I changed the fuel and air filters. Trouble continued. First attempt to start in the morning and if it sat for mor than 3 hours would take several sequences. During those sequences it would turn over the first few, then it would hesitate the next few before it would eventually pick up and run. My thoughts were the fuel system acted like it was loosing prime. I could hear the fuel pump run so I replaced the plugs and leads and checked the fuel filter for water. Problem persisted. I went out of town for a week and now it will not start. I replaced the distributor cap and rotor. I checked spark with a spark checker and I have good spark on all 8 cylinders. I also borrowed a fuel pressure tester and checked the pressure just before the injector. Pressure was at 46 psi. I'm at a loss. Do you have any other suggestions I can check into? Thanks for any recommendations.

Answer
Hi,Scott

 2 causes could be happening in your case,fuel pressure is to low,min press for the CPFI is 56-62 on key up,this can be either a failing fuel pump or a ruptured pulsator that is located at the fuel pump inside tank,there is a GM Bulliten that was issued one for a rupture in the pulsator and also for failing CPFI unit,i have seen both and many,and have replaced both the fuel pump asm with a pulsator that was updated,i would lean towards that,replaced the fuel pump and the new updated pulsator,still availible from GM parts,if the pressure comes up to normal at 56-60 psi and the truck starts fine and runs normal then were good,if in fact after the pump and pulsator installed and the same condition is happening then you would need to replace the CPFI to the new updated one,this unit is expensive.let me know what you find,Thanks


ED