Fuel gauge reading no fuel

[drftem]

Ok so I have a 74 260z and since ive owned this car the fuel gauge has been reading way below the empty point. so I was looking for a new gauge and was told check the wiring to the sender unit. so i started testing for voltage to the sender and got none. so i moved up to see if the gauge was getting power and it is. so i check with the gauge plugged in to see if the yellow signal wire is getting power through the gauge. on initial start up it sends 10-12 volts. after idling for a couple seconds the voltage signal start jumping from .8 to 8 volts. with my voltmeter hooked up to it the gauge reading didnt change.so does this sound like a faulty gauge? also the ampmeter when the car is running stays in the dead center. it never moves?

[260zCaliCar]

About a year ago, I had the same symptom as you (dead fuel gauge), replaced the sending unit, and all has been well ever since. Did it myself, not very difficult. Before you do the replacement, run the car until it's just about out of gas. Or it could get difficult really fast.

Bought the stuff from courtesyparts.com

25060-S30 Fuel Sending Unit - 1970 to 1974 Z S30 $40.29

17342-S30 O-Ring for Fuel Sending Unit - 1970 to 1978 Z S30 $1.74

Hope this helps.

[drftem]

awesome . I will be doing this as soon as i get paid next.

[alhbln]

A thorough test is to drive the car until the tank is empty, as described above. Then remove the sender cable from the fuel sending unit (should be the yellow one), and connect it to one cable of a Multimeter in resistance (ohm) measuring mode. Connect the other cable of the multimeter to ground. Set the multimeter to a range of about 2K (2000 ohm). Now, while filling the tank at the gas station you should see the measured resistance changing accordingly.

If you want to check the fuel gauge itself, buy a cheap 1-2K Ohm potentiometer at an electronics store. Connect one of the two outer pins to ground, and the middle one to the senders input on the fuel gauge. Now, if you turn the potentiometer, the needle should move according to the setting of the variable resistor.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=023-510&source=googleps

Edited October 19, 2009 by alhbln