1986 F-150 NEW GAS TANK. NEW SENDING UNIT SECOND NEW SENDING UNIT. WHEN I FILL UP, THE GUAGE GOES WAY PAST FULL AND DOES NOT MOVE TILL ABOUT HALF IS USED AND THEN IT GOES FAIRLY QUIKLY TO ONE QUARTER. THEN IT STAYS THERE FOR A WHILE AND SLOWLY MOVES DOWN TO ONE EIGHTH AND THEN I RUN OUT OF GAS. HAVE ALREADY CLEANED THE PLUG. ANY IDEAS WOULD BE VERY HELPFUL. THANKS :shaking: :shaking:

Did the ohm ratings from the old sending unit match up with the new one, cause different manufacturers used different ohm parameters for the fuel levels? If thats not it then spend $20 bucks to get another gauge use it for a week, if that fixes the problem keep it, if not return it.

I Did Try Two Other Guages Out Of Parts Trucks I Have. However Did Not Check The Ohms Readings. Will Do This And Let You Know Thanks.

86 is on the cusp, too.

86 and earlier should be 75-10 ohms, 87 and later should be 16-158 ohms.

thanks to bandito and saf-t scissors. i found out i was sold a sending unit for a 1987. the ohms readings were not compatible with the 86 gauge. thanks again. :)