No electrical power after installing electrical fuel pump

STICHN56

MEMBER
1989 CHEVROLET SILVERADO
5.7L
V8
2WD
AUTOMATIC
100,000 MILES

My truck quit running as I was going down highway. After towing to my house, I removed fuel filter and had engine turn over while I was checking. Fuel line pressure. Very low pressure coming out. I installed a brand new AC Delco fuel pump from deal we. Installed it, still no start. I pulled tank again and checked the connector on fuel gauge sensor connector. Found no power on the fuel pump connector side. I got another fuel pump sender unit and installed the dealer fuel pump. Still no start. Anybody help? Is there a possibility of a fuel system cut off switch in the harness somewhere that I am not aware of?

2 Replies

JDL

MECHANIC
16,098 POSTS

Are you missing anything else? Engine cranking, good spark at the plugs? Fuel injector pulse, engine cranking? As far as the fuel pump, when you first turn on the key, no crank, you should get the initial prime, the fuel pump runs for a few seconds. Some pickups have a hot fuel module, it lets the fuel system prime for a little longer.
Check the fuel pump relay, orange should be hot all the time, if you use a jumper wire between hot orange wire and gray, with connector loose, the fuel pump should run, do not have to crank it, Unless I misread the diagram. Sometimes there is a fuel pump prime connector, hopefully, close to the relay, it looks like an electrical connector with nothing plugged into it, If you run a jumper wire from battery positive to that connector, the pump should run, no key needed. If you try that, you might use an inline fuse, just in case. There are several ways to check those circuits. I hope my jabbering was not confusing, sometimes I get carried away?

At the top of page, repair guides, They have a guide for fuel injector testing. It may not be your exact vehicle, but, the basics should be the same. I tried to post the link, it did not work for some reason?