Low Fuel Level Shutdown Warning

Common Symptoms

• COMMANDER display shows fault code 6 and the tower shuts down or refuses to start
• Yellow or red fuel warning indicator lights up on the operator panel
• Engine cranks briefly and dies, or shuts down mid-operation without other apparent cause
• Fuel gauge on the tank reads at or below the low-fuel mark
• Tower lights go dark unexpectedly during a shift or overnight run
• COMMANDER logs a shutdown event with no other active fault codes present
• Engine restarts momentarily after refueling but stumbles if air entered the fuel lines

Probable Causes (Ranked by Likelihood)

• Tank genuinely ran low or empty during extended runtime without refueling Very Likely
• Float-type fuel level sender stuck, corroded, or failed, reporting low when tank has adequate fuel Likely
• Wiring fault or broken wire between fuel sender and COMMANDER controller giving false low reading Possible
• Fuel cap vent plugged, creating a vacuum that slows fuel draw and mimics low-fuel conditions Possible
• Fuel filter severely restricted, starving the engine before the tank is truly empty Possible
• Air leak on the suction side of the fuel system from a cracked hose or loose fitting, causing early vapor lock Less Likely
• COMMANDER controller calibration for fuel sender resistance range is off, triggering fault too early Less Likely

Step-by-Step Diagnostic Procedure

1. Check the physical fuel level first. Open the tank or use the sight glass and dip stick if equipped. If the tank is below one-quarter full, refuel to at least half a tank before doing anything else. If the tank is full and the code is still active, move to the electrical checks below.

2. Inspect the fuel sender wiring at the tank. Trace the two-wire harness from the sender on the tank top down to the COMMANDER wiring harness. Look for chafed insulation, corroded pins, or a connector that has pulled loose. Wiggle the connector with the COMMANDER powered ON and watch whether the fault clears or the reading changes.

3. Measure sender resistance with the tank full. Disconnect the sender harness at the tank and put your multimeter across the sender terminals. Most Allmand float senders read roughly 240 ohms empty and 33 ohms full (standard US sender range). If the tank is full and you read 200 ohms or higher, the sender is bad or stuck.

4. Check supply voltage to the sender circuit. With the harness reconnected and the COMMANDER in RUN, probe the signal wire at the COMMANDER harness connector (not at the tank). You should see a varying DC voltage between roughly 0.5 V and 4.5 V depending on sender type. A flat 0 V or 5 V with no movement points to a wiring open or shorted circuit.

5. Inspect the fuel cap vent. Remove the cap, clear any debris or mud from the vent hole, and attempt a restart. A plugged vent creates a vacuum that collapses fuel flow before the tank reads empty. If the tower runs normally with the cap loose, replace the cap.

6. Pull and inspect the primary fuel filter. Hold it up to a light. Heavy contamination or a filter that looks dark and wet inside suggests fuel quality or water intrusion issues. Replace the filter per the Kubota engine service interval (every 200 hours or annually, whichever comes first) and bleed the system per the Kubota bleed procedure before restarting.

7. If the tank was run dry and the engine died, you must bleed air from the fuel system before the engine will restart reliably. Locate the priming pump (hand pump or electric lift pump depending on the Kubota model), pump until resistance is felt, then crack the bleed screw on the injection pump body one turn, pump until bubble-free fuel flows, and retighten. Repeat at each injector if the engine still cranks without firing. This step requires basic Kubota fuel system familiarity. If you are not comfortable with it, call a diesel tech.

8. If the sender and wiring check out and the fuel level is correct, the COMMANDER controller fuel threshold calibration may need adjustment. This requires accessing the COMMANDER setup menu with the installer-level passcode. Consult the Allmand Night-Lite Pro II COMMANDER operator and service manual, or contact Allmand technical support before changing controller parameters.

Frequently Asked Questions