Put in a new SPECTRA sending unit and it under reads by quite a bit. Full tank reads between 3/4 and full. The old sending unit would peg the needle above full if the tank was filled to the neck. Is there anything that can be done adjustment wise outside of the tank? I'm not dropping that tank again.

 

Of course the only right way would be to remove the sending unit and slightly bend the float , and I can totally understand you not wanting to drop the tank , again .

In actual application as the resistance rises the gauge rises , the reason a disconnected sender will peg the gauge full . Being this as such , you technically could add a low ohm resistor of maybe 10 or 15 ohms , which would "fix" the top (full) end of the gauge but at the expense of skewing the reading at the bottom (empty) end of the gauge , where you need it to be most accurate ! As the tank's level dropped lower the fixed 15 ohm resistance that corrected the top end wouldn't slowly lower along with the resistance of the sender itself , producing a non linear reading with the amount of error becoming worse the lower the level dropped .

In other words , darn it , it you want the gauge to be calibrated right , ya know what ya gotta do . It's a whole lotta work for the average guy working on his back with jackstands , believe me I have sympathy for ya ...

 

I've had that tank out 6 times trying to solve the overheating gas tank issue so many people are having. I think I fixed it. The thought of dropping it again for a damn float is just torturing me.

 

EDGE, did you ever proceed with adding a resistor or dropping the tank again? I have the exact same situation. Replace the sending unit and full tank reads between 1/2 and 3/4. The sending unit is specifically for the 89 Camaro and they tell you to be extra careful when installing so that you don't inadvertently bend the float arm - which I didn't. Very frustrating!