strange fuel gauge issue

[lowrodderchev]

I've went threw a few threads but still haven't found a solution. I have a 75 Chevy, new gauge, new sending unit, new wire from the sending to the gauge and a free new ground to a spot that's bare metal on the frame. Weather the sender is plugged or unplugged it still pegs at 3:00 something ain't right here suggestions? Thanx in advance

[lowrodderchev]

I've been reading this all wrong it hits 3:00 if the sender isn't sending a signal. Oops well must be a bad wire on the sender i guess ill be pulling that out

[Dead Parrot]

A 3 o'clock reading is generally either a bad ground from tank to frame or broken connection between the gauge and the tank. Open circuit means 3 o'clock.

Some suspects a 41 year old truck are:
Corrosion on the gauge contacts, either between the springs and gauge or between the springs and flex circuit board.
The connector contacts between the wiring harness and gauge cluster.
Bad wire from cluster connector to sender.
Ground from tank to frame.
Dual tank switch or switch contacts if you have dual tank setup.

Quick test of wire at sender is to ground the wire. If gauge shows empty, bad sender or ground. If no change, problem is between that point and the gauge.

[lowrodderchev]

i'll try that test thank you. I did a LS swap and I ran a 87 sender I switch out the pump on it so I'm sort of wondering if I possibly discounted the wire on the sender. everything is brand new or I got a bad sender. I just filled my tank Friday so its going to be at least 2 weeks before I can pull the tank to check the sender. unless I cut a hole in my bed. I forgot to mention this is on a 75 chevy blazer which I'm sure is the same as a truck