Turn ignition switch to OFF position. Disconnect electrical connector from fuel tank selector valve.
Turn ignition switch to ON position. Jumper connector terminals for rear fuel tank. Gauge should read fuel level in rear tank. Move selector switch to front tank. Jumper connector terminals for front fuel tank. Gauge should read level in front fuel tank. If fuel gauge reads fuel level in front and rear fuel tanks, replace fuel tank selector valve. If fuel gauge does not indicate fuel level in front and rear fuel tanks, check for faulty fuel gauge, fuel level sensor and/or wiring. Repair or replace as necessary.