I have a 99 chevy blazer, 4.3 4wd auto. I just finished replacing the fuel pump module (pain but no big deal) I started the truck up and started to drive away when it sounded like the front drive shaft was about to fall out. The noise sounds like it is coming from the transfer case, 4wd switch is working (can spin driveshaft by hand in 2wd but not when swithched into 4wd) sounds like a u-jnt with no needle bearings left but all feels tight. What could I have possibly done in replacing the fuel pump that could have caused a drive train problem? Thanks in Advance?
Pobably nothing. But GM uses an epoxy so hold the u-joint in the yolk, making checking the u-joit tricky. A squeeking sound that speeds and slows with speed is a good sign, other than that use a prybar and use the yolk as a pry point see if you get ANY movement. If yes replace the joint.