I have a 91 s10 blazer that has fuel delivery issues. I have replaced the fuel pump after thinking that was the issue but still no start. When the key is turned to the on position I cannot hear the fuel pump turn on as it should. I used a circuit tester light on the grey wire used to power the fuel pump on GM vehicles. Light does not come on at the tank or the fuel pump relay. The grey wire going into the fuel pump relay follows along behind the engine from the relay on the driver's side to the passenger side where the wire ends in a plug. 2 different people looking at it and for the life of me I can't find where that plug goes. The relay is getting no current so I am 99% positive that plug is what powers the fuel pump due to it being a grey wire going to the fuel pump relay. Does anyone know what could be preventing power reaching the fuel pump or where the plug goes?