1999 Chevy Suburban C1500 with 5.7L engine. I have 131,000 Miles. I had problems with the fuel pump running 3 weeks ago. The pump stopped one night and came on in the morning and then stopped for good. I took it out and it would run at 12 volts but I saw somewhere that it runs on 5 or 6 volts and I check the plug in the back and it has 5.42 volts. So I changed the relay and checked the fuse and they are ok. So I ordered a new pump and it worked for 2 weeks and then it stopped on day after a long trip. I changed the relay and checked the fuse again and they are good. It was working on and off and as soon as I thought it was fixed it stopped working a few minutes later. I then replaced the fuel pump wiring harness because I know thats usually a problem and it still will not work. I checked the grounds to the pump and they seem to be good. I also checked the pump on 12 volts and it does kick it on but I still think that the initial prime is around 6 volts. I even changed the oil sending unit because I hear the fuel pump is tied into that. I still have around 5 to 6 volts to the back at the plug. I recently checked it and when I plug it in it drops to 0.42 volts and so does the fuel sending unit but that is working. I am running out of what it may be. I am wondering if the fuel pump has a problem, the computer has a problem or there is a bad ground somewhere. Please help. My next step is to get another fuel pump unit?
Wednesday, November 28th, 2007 AT 5:25 AM