Try your ground for your fuel pump or fuel relay on the firewall passenger side

 

Did you try the groung off the fuel tank/fuel pump

 

Good deal n the parts. Better deal that your truck is running, problem free. More than likely, it was the ground on the fuel pump. This site is the place for getting help with your 1st generation Blazer. A lot of these guys know their poop when it comes to these darn trucks that we all seem to love so much.