s10droopy

Wondering if any one has had this problem? My Blazer was running (warming up) I came back out and it had died. The next day I checked the fuel pressure, zero. I jumped the relay and the pump still wouldnt come on, I even tried banging on the tank (it worked before to get it driven on a trailer) nothing. This now my second pump the first one went out two years ago. So I replaced the pump again. It started right up, then the next morning it wouldnt start. i kept cranking (key on and back off) then I heard the pump come on and it started. So I drove to the gas station to put gas in it since it was low. When I came back out same thing. Only this time I pulled the relay again and jumped it and the pump ran and started. I put the relay back in restarted it and drove it home. Now it starts and runs fine. My problem is this is my wifes vehicle and I dont trust it to haul my kids or get me to work. I dont know if it is the ECM/ECU or some sensor, maybe a ground? The new pump also has good pressure(I checked it with a gauge.)

s10droopy

I did some more checking And cant get the problem to repeat. The fuel pressure is good and holds. I looked at a wiring diagram and the oil pressure switch is in parallel with the relay so if the pressure drops it cuts out the pump. so I unpluged the oil pressure switch and it still starts and runs? but if I pull the fuel pump relay it dies, I dont understand? wondering if 98 blazer is wired different. I know it doesnt have a prime connector. I spent awhile looking for it. Wondering if the PCM is the problem? The next step is going to be checking for loose wire under the fuse block?