Nissan Pickup gas and temo gauge dont work

My girlfriend has a 92 nissan pickup. This car is all over the road, and judging the amount of them driving around I assume they are pretty reliable. However, in my girlfriends pickup the gas and temp gauge do not work. They might read 10% of the time, but mostly never even move. I have checked all fuses, however they all look great.

I assume it might be the gas and temp gauge sender, however I dont know where these are or how hard they are to replace. I work on german cars, so this thing is a little different that what I am used to.

Any help would be appreciated! Also, all other gauges work fine all the time!

There usually is a voltage regulator somewhere in the system that supplies power to the fuel and temperature gauges. It usually is on the circuit board of the dash gauges but it can be in the temperature gauge itself. If you can find a circuit schematic to the Nissan, you will be well on the way to finding where it possibly can be. The voltage regulator is a thermal, bimetal, make and break contact device in a little 1.0 x 0.5 x 0.25 inch can.