My son's 2000 Grand Prix, 3.8L, gas gauge slowly goes to empty activating low fuel light. I changed fuel pump with a boneyard one. Fuel pump works fine but gas gauge always slowly goes to empty even with full tank. Sending unit tested out fine thru range (ohms). Just in case I bought a new sender with the improved copper contacts.
To check, I disconnected the connector at top of fuel pump and rigged a jumper connector using the connector from the old pump. Plugged in the new sender, plugged in harness connector, moved sender arm slowly thru full range. Gauge still goes to empty
Disconnected harness, ran continuity test on pins between fuel pump harness connector and the connector coming thru floor that goes to harness to front Checked out fine. Haven't had a chance to examine harness going to front under carpet yet.
Has anyone had this problem and any ideas where I should start looking? My gut feeling is that there's a loose connector or chafed wire in the body harness going to pcm and dash. Based on my experience thru the years, (approx. 55 years working on cars, etc) the sender should not have to be immersed in fuel to work properly.
Help will be appreciated as it's a pita having to watch the odometer figuring when to fill up; right now that's between 300 and 350 miles to be on safe side. Have gone to 400 miles but that's scary.