Test A: Fuel Gauge Inaccurate

NOTE: Anti-slosh circuitry will cause fuel gauge to take about 20 minutes to go from empty to full if fueled with ignition switch in RUN position.

Turn ignition switch to LOCK position. Disconnect fuel gauge sending unit harness connector C347 (Econoline) or connector C306 (Cutaway). Using Instrument Gauge System Tester (014-R-1063), connect one tester lead to fuel sending unit Yellow/White wire. Connect second lead to ground. Set instrument gauge system tester to 160 ohms. Turn instrument gauge system tester on. Turn ignition switch to RUN position. Wait one minute and read fuel gauge. Fuel gauge should read "F" or above. Turn ignition switch to LOCK position. Set tester to 15 ohms. Wait one minute and read fuel gauge. Turn ignition switch to RUN position. Fuel gauge should read "E" or below. If fuel gauge reads as specified, disconnect tester and go to next step. If fuel gauge does not read as specified, disconnect tester and go to step 5.
Visually inspect fuel tank for damage. If fuel tank is okay, go to next step. If fuel tank is damaged, repair or replace as necessary.
Visually inspect fuel pump assembly for damage or corroded connections. Inspect float and float rod. If fuel pump assembly is okay, replace fuel level sender. See FUEL LEVEL SENDER under REMOVAL & INSTALLATION. If fuel pump assembly is damaged, replace assembly and retest system.
Measure resistance between ground and Black/Yellow wire at fuel level sending unit harness connector C347 (Econoline) or connector C306 (Cutaway). If resistance is 5 ohms or less, replace instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. If resistance is more than 5 ohms, repair open in Black/Yellow wire. See WIRING DIAGRAMS .

Fig 1: Identifying Instrument Cluster Connector C224 Terminals
Courtesy of FORD MOTOR CO.
Turn ignition switch to LOCK position. Disconnect instrument cluster harness connector C224. Measure resistance of Yellow/White wire between terminal No. 10 at instrument cluster connector C224 and fuel level sending unit harness connector C347 (Econoline) C306 (Cutaway). See Fig 1. Resistance should be 5 ohms or less. Measure resistance between ground and terminal No. 10 (Yellow/White wire) at instrument cluster connector C224. Resistance should be more than 10 k/ohms.
If resistance is as specified, replace instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. If resistance is not as specified, repair open or short to ground in Yellow/White wire. On Natural Gas Vehicle (NGV), check Yellow/White Wire between instrument cluster and NGV module. On other than NGV, check Yellow/White wire between instrument cluster, PCM, in-transit fuel pump module, and fuel pump module. See WIRING DIAGRAMS .