Fuel Gauge incorrect reading

Has anyone had the problem of the gas gauge not reading right. when its full the gauge says empty or half then 5 minutes later quarter full. i swap'd the gauge cluster itself with 3 different ones and i also swap'd out the sending unit in the tank...same thing nothing changed, i broke down and bought a brand new fuel gauge and sending unit from mazda and installed them and still nothing. spent a bunch thru mazda for the parts and they dont work either..same thing.. now that i have bought new parts. I WOULD LIKE THE DARN THINGS TO WORK!!!! Anyone got any clues at to what it might be........

wow, I usually drive 200 to 250 miles then put gas in it

phil- the fuel gauge and temp gauge share a common circuit in the cluster assmbly. Usually it is just a bad sending unit in the tank. Be sure your wiring is good from the tank to the guage. Also check your coolant temp sending unit. Does the temp gauge read correctly?

mine was doing the same thing I changed the sending unit and it did'nt help it turned out it was the connector that plugs into the sending unit was all corroded.

mines pretty sweet, you fill it up, and it shows empty, then when it starts gettin close to 1/4 tank, it start rising up, then when it gets to 1/4 tank, then starts goin back down til its empty.

Mine shows full all the time, no sending unit in mine

sounds to me like a wiring problem your fuel gauge reads off measuring amperes so if you got a bad connection or maybe a pinched wire that would cause it to read incorrectly if you know how to use a multi meter it should tell you in the repair manual for that truck what it should read at full and empty

didnt find anything about correct amp readings in my book, im about googled out, does anyone no the amps its supposed to read and am i testing it at the sending unit. anyone every tested one before, not exactly sure how to do it, i no how to read my volt meter, but its not getting me very far. lol.

I have the same prob with my fuel gauge...
=(

i have never had that problem with my two mazdas. i usually go 300 miles then fill it up with my trucks.