Erratic fuel gauge

The other day after filling the truck up noticed the fuel gauge was acting odd. First within 20 miles it dropped to 3/4 of a tank then while driving on flat pavement would change between 3/4-5/8. It's been getting worse, last night after starting the truck the gauge just fell to zero. Came back up this morning and fell again later on.

From what I've found it seems to either be a bad ground or faulty sending unit. I had just swapped in a 34/78 so I had to extend the body ground from the battery. Not sure if that has anything to do with it as far as connection or just a coincidence. Just looking to see if anybody else has had this happen and what they did to fix it. (Truck is an 02 xtra cab v6 4x4)

 

Check the wires running to the intake manifold from the OBD port: they were loose on my truck and gave me fuel and temp weirdness. Not to mention the engine dying when they got really loose! Took the bolt off, applied blue locktite, and screwed them onto the manifold. Truck runs really good now...

 

My '02 does it when the weather starts cooling down.

 

yep mine too. Anything below 50 degree's and it likes to dance, up and then all the way down and then eventually back to where it belongs. Gets worse when it's cold and wet. Summer time is always correct.

 

Fuel sender. Should be on/in tank. Try easy stuff first though.

 

It's been fine the past two days guessing the cold got the better of it.