Fuel Indication System

Preliminary Checks

1. Visually inspect fuel tank for damage. A fuel tank that is collapsed or distorted from its normal shape will seriously affect fuel indicating system operation.

2. A vehicle may be encountered with a fuel tank that does not fill completely. This will result in the fuel gauge not reaching FULL mark. Check by shaking vehicle after first fuel blowback or pump nozzle cutoff and then slowly metering fuel into tank with shutoff nozzle withdrawn to just inside the leaded fuel restrictor door. If fuel gauge reaches full after this procedure, fuel indication system is operating satisfactorily.

Operational Test

Tools Required:

• Rotunda Instrument Gauge System Tester 021-00055

Follow the instructions with the Rotunda Instrument Gauge System Tester 021-00055 or equivalent. If a tester is not available, refer to Pinpoint Test A and Pinpoint Test B.

Calibration Test

Tools Required:

• Rotunda Instrument Gauge System Tester 021-00055

The required test equipment consists of a Rotunda Instrument Gauge System Tester 021-00055 or equivalent, a pair of 22 ohm and 145 ohm resistors or another fuel sender of known quality.

If test is performed with resistors: Disconnect the wiring connector at the sender unit, connect the resistor between the gauge lead and a suitable ground, and turn ignition switch to the ON position. With the 145 ohm resistor, the gauge pointer should contact the FULL mark at minimum edge of pointer to edge of mark. With the 22 ohm resistor, the gauge pointer should contact the EMPTY mark (edge of pointer to edge of mark).

If test is performed with a fuel sender of known quality, use the following procedure:

1. Turn ignition switch to the OFF position.

2. Disconnect the wiring connector from the sender and connect it to the test sender.

3. Move the float rod away from the fuel filter against the FULL stop position (approximately 145 ohms). Wait approximately 30 seconds and turn ignition switch to the ON position. The gauge should read on or above the FULL mark.

4. Move the float rod toward the fuel filter against the EMPTY stop position (approximately 22 ohms). Turn ignition switch to the OFF position. Wait approximately 30 seconds and turn ignition switch to the ON position. The gauge should read on or below the EMPTY mark.

5. If the gauge performs as indicated, perform the fuel sender unit test(s), Pinpoint Test E .

6. If the gauge is out of calibration at the EMPTY mark, or both the EMPTY mark, or both the EMPTY and FULL mark, replace the gauge.

Refer to the pinpoint tests for magnetic gauge diagnosis.   

PINPOINT TEST A: FUEL GAUGE INOPERATIVE—POINTER DOES NOT MOVE

A1 VERIFY CONDITION  

• Verify condition.

• Does pointer move?

GO to D1.

No
GO to A2.

 

A2 CHECK OTHER GAUGES

• Check power to cluster. With ignition ON, observe other gauges and warning indicators for proper operation. If necessary, use Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent or a test lamp to verify voltage at B+ terminal of cluster connector.

• Do gauges and warning indicators operate properly and is voltage present at cluster?

Yes
GO to C1.

No
GO to B1.

  

PINPOINT TEST B: FUEL GAUGE INOPERATIVE

 

B1 VERIFY POWER AT FUSE PANEL (LOAD SIDE) 

• Use voltmeter to verify system voltage at load side of warning indicator fuse.

• Is voltage present at load side of fuse?

Yes
GO to C1.

No
GO to B2.

 

B2 VERIFY POWER AT FUSE PANEL (FEED SIDE)

• Use voltmeter to verify system voltage at feed side of warning indicator fuse.

• Is voltage present at feed side of fuse?

Yes
REPLACE fuse. GO to A1.

No
SERVICE wiring to fuse panel. GO to A1.

 

PINPOINT TEST C: CLUSTER DIAGNOSIS

 

C1 VERIFY POWER AT CLUSTER  

• Cluster connectors installed.

• Partially remove cluster.

• Check for voltage at cluster connector and gauge terminal.

• Use Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent.

• Is voltage at cluster connector and gauge terminal?

Yes
GO to C2.

No
SERVICE circuit. GO to A1.

 

C2 VERIFY GROUND CIRCUIT AT CLUSTER

• Use Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent to check continuity of cluster and gauge ground circuits.

• Is there continuity?

Yes
GO to D1.

No
SERVICE circuit. GO to A1.

 

PINPOINT TEST D: FUEL GAUGE DIAGNOSIS

 

D1 CHECK TEST BOX (LOW)  

• Turn ignition to OFF position.

• Insert Rotunda Instrument Gauge System Tester 021-00055 or equivalent in sender circuit.

• Access and disconnect the instrument cluster 14 pin connector and connect tester to cluster side of connector.

• Set tester to 22 ohms.

• Turn ignition to RUN position, wait 60 seconds and read fuel gauge .

• Does gauge read EMPTY?

Yes
GO to D4.

No
GO to D2.

 

D2 CHECK TEST BOX (RETEST)

• Turn ignition switch to OFF position.

• Turn ignition switch to RUN position.

• Tap lightly on instrument panel, wait 60 seconds and read fuel gauge .

• Does fuel gauge read EMPTY?

Yes
GO to D4.

No
GO to D3.

 

D3 ANTI-SLOSH MODULE BYPASS TEST

• Turn ignition switch to OFF position.

• Remove instrument cluster and inspect flexible circuit.

• Remove anti-slosh module and connect a jumper wire from Gauge Tester directly to fuel gauge 'SIG' terminal.

• Install instrument cluster.

• Turn ignition switch to RUN position and read fuel gauge .

• Does fuel gauge read EMPTY?

Yes
REPLACE anti-slosh module. GO to D1.

No
REPLACE fuel gauge . INSTALL anti-slosh module. GO to D1.

 

D4 CHECK TEST BOX (HIGH)

• Turn ignition switch to OFF position.

• With Rotunda Gauge System Tester 021-00055 or equivalent connected as in Step D1, set tester to 145 ohms.

• Turn ignition switch to RUN position.

• Wait 60 seconds and read fuel gauge .

• Does fuel gauge read FULL?

Yes
GO to D6.

No
GO to D5.

 

D5 ANTI-SLOSH MODULE BYPASS TEST

• Turn ignition switch to OFF position.

• Remove instrument cluster and inspect flexible circuit.

• Remove anti-slosh module.

• Connect a jumper wire from tester to fuel gauge 'SIG' terminal.

• Turn ignition switch to RUN position and read fuel gauge .

• Does gauge read FULL?

Yes
REPLACE anti-slosh module. GO to D1.

No
REPLACE fuel gauge . GO to D1.

 

D6 INSPECT FUEL TANK

• Inspect fuel tank for damage or distortion.

• Is there damage?

Yes
REPLACE fuel tank .

No
GO to E1.

  

PINPOINT TEST E: FUEL SENDER DIAGNOSIS

 

E1 CHECK TEST BOX —EMPTY STOP  

• Connect one lead of Digital Volt-Ohmmeter 007-00001 or equivalent to the fuel sender signal lead and the other lead to ground.

  NOTE: Float rod is against empty stop (closest to filter).

Ohmmeter reads 14-18 ohms
GO to E2.

Ohmmeter reads less than 14 ohms or greater than 18 ohms
REPLACE fuel sender.

 

E2 CHECK TEST BOX —FULL STOP

• Connect one lead of Digital Volt-Ohmmeter 007-00001 or equivalent to the fuel sender signal lead and the other lead to sender ground.

  NOTE: Float rod is against full stop.

Ohmmeter reads 155-165 ohms
GO to E3.

Ohmmeter reads less than 155 ohms or greater than 165 ohms
REPLACE fuel sender.

 

E3 CHECK TEST BOX —FLOAT ROD LEVEL

• Connect one lead to Digital Volt-Ohmmeter 007-00001 or equivalent to the fuel sender signal lead and the other lead to sender ground.

• Slowly move float rod from full stop to empty stop.

Ohmmeter reading jumps to open condition while decreasing
REPLACE fuel sender.

Ohmmeter reading decreases slowly
GO to E4.

 

E4 FUEL SENDER INSPECTION

• Inspect fuel sender.

• Inspect float and float rod.

Float rod is distorted
REPLACE sender.

Float is badly distorted/damaged hitting the filter
REPLACE sender. GO to E5.

 

E5 CHECK HARNESS CONNECTOR —EMPTY STOP

• Attach all fuel indication connectors.

• Move float rod to EMPTY STOP position.

• Turn ignition to RUN position.

• Wait 60 seconds.

• Read fuel gauge .

• Does fuel gauge read EMPTY?

Yes
GO to E6.

No
GO to A1.

 

E6 CHECK HARNESS CONNECTOR —FULL STOP

• Attach all fuel indication connectors.

• Move float rod to FULL STOP position.

• Turn ignition to RUN position.

• Wait 60 seconds.

• Read fuel gauge .

• Does fuel gauge read FULL?

Yes
Fuel sender OK.

No
GO to A1.

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