So I have swapped all 93 wiring harnesses and the dash from a RC into my 74 PW with an in cab fuel tank. The gauge initially read 3/4 tank when I turned the key on and didn't fluctuate at all. But when I drove it the gauge fluctuated about 1/4 tank consistently, the roads are really crappy here. It didn't do this before the swap and my 92 doesn't do it either. I made two 24 mile round trips with the truck, then on it's third trip the gauge was fluctuating down to a 1/4 tank so I figured I better fill it up to be safe. I put 27 gallons in what is supposedly a 24 gallon tank shock so I'm thinking it was about empty. I know the resistance values for the senders are the same.

So my question is, is there a mismatch here I'm not aware of between the gauge type and the sender and is there anything I can do to correct it or compensate for it?

"Follow me the wise man said, but he walked behind"


'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost conversion.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.