I have a 98 Sierra, 5.7L 4WD Shorty. About 2 months age I noticed the needle about the 1/2 way point vibrating furiously about a half a needle width wide. Did this all the way down to the red. Full is ok then starts about midway. I didn't see too many posts about fuel transmitters being bad so I though to ask. Also, I don't use Shell gas.

you could check the sending unit with your volt meter to see if your getting the same flucuation, the voltage would fluctuate the same as the needle on your gauge, at least this would pinpoint the problem device.

are any other guages suspect? not working properly?

i also have a 98 z71 5.7........same thing started today on the way home ...half way and started vibrating like crazy....did you figure it out?????