Toyota Repair: tercel 1994, 75,000 miles, auto trans, haynes repair manual, toyota tercel

Question
after I turn the key on, the fuel gauge will go all the way up beyond full. Then when I start the engine  the temperature gauge will slowly move up so that after about 3 minutes it goes beyond "H". I have check all the ground connections that are accessible. I have removed the instrument cluster bezel, but decided to ask around first before I cause a major problem. The car is operating normally otherwise, my daughter just have to refill gas more often and rely on the odometer to estimate gas. I have the Toyota tercel 87 to 94 Haynes repair manual for reference. I can not yet locate the fuel and temperature sending units, book does not show. But I did disconnect the fuel pump behind the rear seat and the fuel gauge needle drop all the way down. Is the fuel pump and sending unit in one assembly? What could be causing these gauges to malfunction? Your help would be most appreciated. Thanks.


JOSE

Answer
The fuel level sender is part of the fuel pump, the engine temp sender is located near the thermostat housing, with the key on and grounding the connector from the temp sender the temp gauge should go all the way up(don't do this any longer than necessary to avoid burning out the in dash gauge)with the connector off the gauge should return to zero, if this is the case the sender unit should be replaced.
If the gauge does not do this it will be necessary to replace the instrument cluster printed circuit board or the complete cluster, if replacing the temp sender makes the temp gauge work correctly then replace the fuel level sender in the tank also. There is a voltage regulator built into the instrument cluster that drops the voltage for the gauges, they do not receive 12 volt battery voltage, if this regulator malfunctions it can make more than one of the gauges give incorrect readings.