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1947 Cadillac Erratic Gas Gauge

Started by bill_boos, February 07, 2020, 06:27:58 PM

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Gas gauge stays pegged at full while driving. At stopped, it bounces between half and full.
This with about 1/2 tank of gas. Should I be looking for a gauge problem, sending unit or ???. Anyone ever seen or heard of this problem and how to diagnose?

Thanks, Bill
2013 SL 550
2006 Bentley GT Continental
2003 CL 600
1947 Lincoln Continental Cabriolet
1949 Cadillac Sedan (sold years ago)
1956 Cadillac Convertible (sold)
1947 Cadillac Sedanette (Just Bought Oct 2019)

Bob Schuman

Very likely that it is a problem of a bad grounding of the sensor in the top of the tank. Run a new ground wire from one of the five sending unit mounting screws to a place cleaned and shiny on the frame, which should fix it. The sender is very difficult to access from under the car with the tank in place, but on some cars a previous owner has cut and access opening in the trunk floor  and covered it with a homemade plate. That makes sender access very easy.
Bob Schuman, CLC#254
1951 6137
2017 CT6-unsatisfactory (repurchased by GM)
1948 Olds 98 Custom
2020 XT6