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- - Fuel guage (https://67-72chevytrucks.com/vboard/showthread.php?t=332411)

My wife drives a 2000 Blazer 2wd 2 door.The fuel guage has started acting up.It will move around from 1/4 -3/4 and it does it randomly.I'm thinking a ground or bad sending unit.Just thought I would ask if anyone has had a problem or any experience with this?

Notorious fuel guage problems are common. Mostly likely, a new sending unit is required. Check the ground strap if possible. You may need to lower the tank to find it. I've yet to pull a tank on a Blazer or Jimmy. I'm not looking forward to replacing the fuel pump when it fails.

they have problems with both the sender (wiping fingers break) and the slosh module. I would test the sender first as it's the easiest to diagnose.

remove the spare tire for crawling room. with a drop light look at the top rear of tank. you will see the fuel pump module (white plastic circle with 3 tubes and 2 wiring connectors). look for the harness connector with 4 wires (2 blacks, a purple, and a gray). the purple is the fuel gauge signal, the gray is fuel pump feed, and the blacks are the grounds. remove the connector lock (blue thingy, just pull it out of connector body, assuming it hasn't been pulled before and lost) and test the sender for resistance with an ohm meter. the ground for the sender is opposite the signal wire, not next to it. then have someone shake the car side to side while you look for a sudden increase in resistance.
disclaimer; I use a pigtail I salvaged from another vehicle to make testing connections more reliable. I actually have about 3 or 4 of them, want one?

my wife has a 2001 blazer with the same problem,the gauge just quit working.it will go to full tank when it's full. but then bounce around when the level is low.they want over a $1000.00 to drop tank change the sending unit,might as well change the pump. also they said that way i don't have to drop tank later to change pump. so she just figures her mileage so she knows when to get gas. or waits for the low fuel light to come on.