If I ground the (yellow) wire in the plug that's normally attached to the sender and flip the key to ACC, shouldn't a working gauge go to the full position? Mine isn't...and if it's supposed to it's either a dead gauge or wire to it.
Another layer of the onion.
'85 F150 XLT 4X4 with 300 c.i. six & NP435 four speed.
'63 Studebaker Avanti - 350/TH350
'59 Rambler Super - OHV 6 with 3-speed OD
'58 Studebaker Scotsman sedan - 289 with 3-speed OD