Yes. Explain where you stuck the black lead of your DMM when you measured the sender resistance. The factory's ground was a metal clip across the short rubber hose on the sender. Assuming that iffy connection works, that only takes the sender's gnd to the fuel tube which must be grounded to the car body via the mounting clips (rusty & under-coating). Gasoline is a non-conductor. Some here fab their own ground wire to the sender.