QuestionBoth the fuel quantity and Engine Temp gages on my 1990
Ford Tempo are defective. The Fuel gage reads about half a tank with the tank full. The temp gauge never moves off cold. There are two temp sensors shown in the Haynes manual
for this model. One connects to the engine control computer. I can substitute a five thousand ohm variable resistor for that sensor and vary the engine speed and
eventually turn on the check engine light.
The voltage to the other sensor which is shown in the diagram is a steady twelve volts on the red/white wire.
using a variable resistor, I can turn on the cooling fan
but the temp gage never moves. I am at the end of my information because the Haynes diagram doesn't have
any information about the instrument panel or take
the voltage and gauge all the way back to the source.
I suspect the fuel gage and temp gage have a common
source and fixing one problem will fix the other.
The car is a 1990 Ford Tempo four door sedan
The engine is the four cylinder fuel injected type.
Answerthe only thing i see common between the two is fuse number 18
they did have some problems with sending units in the tank and actually had dealers return those in stock-so sending units may not be available from the dealer anymore since the car is 18 years old. i would be suspicious of bad tank sending unit.
a simple check on temp sending unit is to unplug wire and ground it guage should go to hot and unplugged should be cold if it does you either have a bad sensor or stuck open thermostat-if not you may have guage problem
