My gas gauge either reads full or empty, nothing in between. Is there any way to test the sending unit without dropping the tank.

 

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https://www.yotatech.com/forums/f2/how-access-fuel-sending-unit-99-a-65310/

 

I had a problem with our gauge not reading below 1/4 tank. After dropping the tank and examining everything, I found out that our sending unit had a bad ground. You can check this without dropping the tank, Simply remove the access cover under the rear seat and attach an external ground to one of the sending unit attachment screws. See if this helps.

 

Thanks, the ground may be it, I removed the cover and unplugged the connection just checking everything and now it shows signs of life.