My fuel gauge cant decide on how much gas is in the tank. It will go from a 1/4 tank down to the E symbol when there is a 1/4 tank of gas in there. It sometimes does it when im stopped then after a mile or so will go back to where it should be. Is this a sighn my fuel pump is on its way out? Is it ground wire probalem? I did test my coolent for voltage and it read .11 volt on the meter instead of around 3-5 for being good. The .11 would indecate a lose or bad ground but i dont know if it pertains to what is happening to my fuel gauge.

93 montero sr 3 inch body lift 31x11.50 super swamper ltb, 2 8inch 130 watt pro comp off road lights, 2 55w lights on the rear bumper, rear air locker, magnaflow exhaust muffler,superwinch manual hubs,15x8 black rock crawlers (steel)