Hello,
I have a 1990 Chevy K1500 Silverado, 350 TBI. A few months ago the truck had a hard time starting. I determined the fuel pump wasn't getting power, so I replaced the relay but that didn't fix it. The pump is new. I finally jumpered a wire from the ignition through an on/off switch that feeds power directly to the fuel pump. That redneck fix works for now, but now I have another problem. I just timed it today. Unplugged the tan/brown jumper wire and set base timing to 4degrees. Reset ECM by unplugging battery. Now the truck runs perfect, smooth idle, good power. Only problem is that I need to pour a little gas into the throttle body every time I want to start it, otherwise it just cranks and doesn't even try. With gas in the TB, it starts right up and runs perfectly. I know the fuel pump is running since I'm giving it 12v and can hear it running...that and the the fact that is drives great once it's started. It's like the fuel injectors aren't firing when I turn it over.

I wonder what is causing this. Maybe something associated with my original problem of the fuel pump not getting juice, something electrical maybe, or perhaps a bad sensor somewhere. On that topic, I can occasionally turn off my direct 12v supply to the fuel pump and the truck will stay running, but it doesn't last. Sometime it works for a while, other times it shuts right off. That seems pretty random.

Thanks for any help

 

Check your oil pressure sensor - it is tied into the fuel pump circuit.