1) Remove the fuel sub level sensor.
2) Measure the resistance between the fuel sub level sensor connectors when the float is in FULL and EMPTY position.
Connector & terminal
(R59) No. 1 — No. 2:
Is the resistance 1.0 to 3.0 Ω (FULL) and 61 to 63 Ω (EMPTY)?
Replace the fuel sub level sensor.