1968 barracuda temp gauge and fuel level inop

Set your meter to the 200 ohm range. Touch the two test probe leads together, the meter should read zero or close to it. Put the black lead from the meter on the temperature sender base where it screws into the engine block. Scrape it around a little to clean off the metal a bit. Put the red meter lead on the center post of the temperature sender and again scrape it around a bit. Okay, now read the meter- it should be somewhere between 10 and 80 depending on engine temperature. 80=cold, 10= really hot. Normal engine temperature should be somewhere around 25 or so ohms. If you get the same reading you got with the meter leads held together the sensor is shorted and will need to be replaced and it may have taken out the gauge. If the sensor reads above 80 ohms it is bad and will need to be replaced.