I tested it in the tank and out the tank. ... I know the gage will go to full because if the wires are disconnected it defaults to full. ...
When the gauge wire is disconnected from the sender with the ignition switched ON, the fuel gauge needle should swing well past FULL to the 3:00 o'clock position. When you ground the sender wire the gauge should quickly drop to EMPTY.
You can also perform a rudimentary check on the sending unit if you have a decent ohmmeter. With the sender float in its lowest position (EMPTY) an ohmmeter with its leads clipped to the sending unit frame and sender wire pin terminal should indicate ~0 Ohm. Moving the float to its highest position (FULL) the ohmmeter should indicate ~90 Ohms; midway (1/2 Tank) it should indicate ~45 Ohms.
If the sender float is closed cell nitrophyl foam, give it a firm squeeze between your finger and thumb nail. If the float oozes fuel when squeezed, the float is saturated and the sender should be replaced with another brand that uses better quality materials.
dang wish I had this ohm info before I re installed the tank. Lol. I will try that next time I take it out. The sending u it float is plastic. (Got it from NAPA) Seems to float fine. It just won't read over 1/4 tank. I did move the float to many positions with the truck on and it never would read over 1/4 but less than 1/4 works as it should.
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