The sending unit is a thin wire wrapped around a nonconductive board that a arm moves across.
The arm is probably rusted in place.
Take the sending unit out to see what is wrong.
I have cleaned up 1 or 2 & gotten them working.

 

The sending unit is still available from the nissan dealer if it is bad, Bought one a couple of months ago. Around $35.00 bucks.

 

Ok ... where is the sending unit located?Also how can get it out to clean os replace??
Thanks

 

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The sending unit is in the top of the tank.
You get to it through a excess in the floor of the hatch.
Soak the locking ring with diesel fuel or some kind of oil over night.
Use a punch, screwdriver or dull chisel to turn the locking ring counterclockwise

 

Special thanks for all you guys.....I love this forum.
Jamal (borini63)

1978 280Z BP needs paint jop.