You probably have a lower-temp thermostat installed.
The OEM spec is 195 degrees, and that 15 degrees (if you have a 180 in there) WILL make a big difference on the gauge.

 

like dodgerules86 suggested, you probably have a 180 thermostat. i have one in mine, and my temp gauge never reads over an eighth over the normal line.

 

Well the fuel gauge probelm was in fact the float hitting the side of the tank on my '94, just like the '91. Since I knew what the problem most likely was, I just lowered the tank enough, without disconnecting anything, to loosen the pump enough to just rotate it while it was still inside the tank. Bingo! The float was against the wall and the gauge now works. Still have to look into the temp gauge though, just haven't had the time.

 

hi all,

Thanks all the info. I have now fix my temp. gauge problem. after I read the tread about thermostat. so what I did is flush my coolant change the thermostat with 195 and change the coolant temp. sensor, I change also my coolant temp. sending unit. and my temp. gauge work properly. as for fuel gauge just order 1 online fuel pump assy. cost me $111.79 plus shipping at rack auto. I have question. which is easier to remove the fuel pump. remove the tank or remove the bed. I need suggestion or commet on this. again thanks for all the info.

 

It's really easy to just remove the tank. First disconnect the fill and vent hoses up behind the fuel door, then remove the two nuts that are above the driveline on the tank straps and bend the straps back out from underneath the tank, then just lower it down. First siphon all the gas out so it's not heavy. Once the tank is about 1/2 way down you'll have to then disconnect the wiring harness and gas lines from the top of the pump assembly before bringing it all the way down. Pull it out from under the truck and replace the pump assembly, making sure the float will not be hitting the side wall of the tank when it floats up. Then install the tank in reverse order.
If you pull the bed off, you still have to disconnect the fill and vent hoses and the tail lights and any other wires, lines, hoses that may be attached to the bed. Then all the bolts fastening the bed to the frame, then get a couple guys to help lift the bed up and off. More trouble if you ask me.