Some test results; with the generous help in this forum and from my wife (best friend), I was able to find enough info to conduct an instrument cluster and a fuel guage test. There may not be a problem with the fuel sending units, but I'll hold off until I run enough fuel out to test again.
Test 6.1

3/4 Full mark test: 39.0/23.2/62.3L=16.54Gal.
Full Tank test: 55.0/27.0/82.0L=21.67Gal
Drove 120.9 miles (guage just left of full) test: 49.1/24.2/73.3L=19.36Gal

2.3 gallons used @ 19MPG, = 418 miles per tank.


We recalled how our 325i fuel guage would sit on the right side for a long period, then dump towards "E" dramatically. The systems might be the same.


Intirim projects; P/S slow leak, F/Passenger Window Regulator, and Accelerator Pedal.


Many thanks!


G

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2018 F250 STX

2002 BMWX5; 3.0i
2016 Nissan Altima (OR), 2008 Ford Escape (OR), 1998 K1500 (GA), 1990 BMW 325i (GA, KY, & OR), 1992? Ford Explorer (TX-GA) , 1987 Ford Ranger (GA), 1982 Ford Courier (TX), 1986 Mercedes 260 (Germany), 1988 Izuzu Trooper II (NC), two 1970 Jeepster Commandos (NC), 1979 Monte Carlo (NC)
1968 Ford 3/4T truck (CA), 1972 Ford Courier (CA), 1972 Ford Maverick (CA), 197? Yamaha 125 (CA), 196? Honda Trail 90 (CA)