Hi guys. Also consider a bad ground on the gas tank. That has been a real common problem on the smaller Blazers with steel tanks. One clue is the pump works okay for a while after the tank was removed. The ground for the pump is made through the straps that hold the tank on. To verify they are not making a good connection, connect a test light to a paint-free point on the body, then probe the side of the tank while a helper cranks the engine. Twelve volts only goes to the pump for one second after turning on the ignition switch, then again during engine rotation, (cranking or running). If the ground is bad, you'll find twelve volts right on the tank.
The fix for this is to drill a small hole through the flange joining the top and bottom halves, outside of the welded seam. Run a self-tapping screw into the hole, and connect a wire to it. Connect the other end of the wire to a screw in the body or frame rail. If that is not the cause of a dead pump, HMAC300 will continue on with the diagnosis.
Friday, December 30th, 2016 AT 3:51 PM