lefty

Hello Everyone,

After reading all the great posts about the Maxima, I purchased one yesterday. 1998 Maxima SE with only 28000 Kms....thats right, kms not miles

Anyway, I filled up the car with gas today and the gage only read it at a little over 3/4 of a tank.

I thought I did not put enough gas in so I went back and of course I overfilled it.

Why is the gage reading wrong?

The car is still under waranty until 100 000 kms or two more years.

Please let me know your thoughts.

Thanks,

lefty

justmax

if it's still under warranty take it to the dealer... I've never heard of this problem.

Daniel B. Martin

If the dealer will fix this at no cost, let him do it. If you have to do it yourself, read on ...


The fuel pump is located inside the gas tank. The fuel gauge sending unit is attached to the fuel pump. It consists of a float which operates a variable resistor. For vehicles with conventional analog fuel gauges the resistance value for a full tank is 5 ohms and for an empty tank is 80 ohms.

An on/off switch is incorporated into the gauge sending unit. The switch is normally open, but closes when the fuel level is close to empty. This switch operates the Low Fuel dashboard warning light.

The Low Fuel warning light circuit is simple. The light has +12 volts whenever the ignition is ON. The ground side of the circuit is completed by the in-tank switch, as described above.


This diagnostic procedure takes ten minutes. It is not difficult and does not require any special tools. It should be carried out with a full tank. You need an ohmmeter, a pair of test leads and two resistors (5 ohms and 80 ohms). You may purchase these items at an electronics store (Radio Shack, etc.) or borrow them from an electronics hobbyist.

Diagnosis procedure.

1) Move both front seats all the way forward. This is to give you more room to work in the rear seat area.

2) Fasten all rear seat seat belts. This is to keep them out of the way and facilitate subsequent installation of the back seat.

3) There are two release latches at the bottom leading edge of the rear seat bottom cushion. Pull these latches toward the front of the car.

4) Lift the leading edge of the rear seat bottom cushion and pull the cushion toward the front of the car. Remove the cushion from the car.

5) Note the fuel pump access access cover in the center of the car. Remove three 10mm bolts. Lift the access cover and move it aside. You can now see the top of the fuel tank.

6) There are two electric connectors. Remove the one on the passenger side. No tools are necessary, just press the latch, wiggle, jiggle, and lift. This is connector B22. It has a gray plastic shell with 4 terminals.

7) Turn the ignition ON. No need to start the engine.

8) Note that one of the wires leading into the disconnected connector is red with a black tracer. Use a test lead to connect this terminal to ground. The Low Fuel warning light should go on. Remove the test lead. The light should go off.

9) If the Low Fuel warning light did not go on the dashboard bulb is defective or the wire between the fuel tank and dashboard has an open circuit.

10) If the Low Fuel warning light did go on the in-tank Low Fuel switch is defective.

11) View the connector which is mounted in the tank with the latch at the 12 o'clock position. You are looking at four terminals in a square configuration. In this orientation the upper left hand terminal is designated E and the lower right hand terminal is designated G. Measure the resistance across terminals E and G. If not 5-8 ohms, the sending unit is suspect.

12) Note that one of the wires leading into the disconnected connector is orange with a blue tracer. Turn the ignition switch to ON. Use a test lead to connect this terminal to one end of the 5 ohm resistor, and another test lead to connect the other side of the resistor to ground. The gauge should read FULL. Then use the 80 ohm resistor in the same fashion. The gauge should read EMPTY. If the gauge does not display the expected readings, the gauge itself or the wiring from the tank to the Combination Meter is suspect.


If the sending unit is faulty you may have to replace the assembly. Instructions for removing the pump are found in the Chilton repair manual (page 5-2) and the Haynes repair manual (page 4-4).

Alex97se

same thing happened to my little 87 sentra. Wasn't worth fixing on that beater, just counted the miles on the odometer. Having a functioning gas gauge is a great thing though, good luck.