Inspecting the Fuel Level Sender Component
Warning: As with all pressure vessels, CNG/LNG storage and fuel delivery systems are inherently dangerous and should be treated as such. Beyond the visual inspections listed below, all maintenance and repairs to compressed natural gas (CNG) or liquified natural gas (LNG) systems should be performed by trained personnel. Individuals who are not trained in all aspects concerning CNG/ LNG fuel delivery systems are not permitted to service, maintain, test, or inspect a system in any way. Failure to comply with safety regulations may lead to fire or explosion, resulting in property damage, personal injury, or death.
The following inspections must be performed by a qualified technician, in accordance with the manufacturer's established inspection criteria.
All tank components should be allowed to defrost before conducting the following inspections.
Notice: Do not use a high-pressure washer or steam cleaner on natural gas fuel system plumbing components, as this can introduce moisture and contaminants into the threads of the fittings and damage the sealants.
Gas detection sensors are located on the cab overhead console and in the engine compartment on the frontwall. The sensors are located in high areas, where rising gas vapors will pass by or accumulate. Do not use a high-pressure washer, steam cleaner, or silicone-based chemicals on the gas detection sensors, as this may permanently disable the sensors. When cleaning the vehicle, cover the sensors with a plastic covering. Keep the sensors covered until the area has been cleared of any cleaning fumes. Harsh chemicals and extremely high temperatures may damage the sensor.
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Pressure Control Regulator
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Vapor Shutoff Valve
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Fuel Fill Hose
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Secondary Relief Valve (red cap)
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Fuel Fill Fitting
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Fuel Level Sender Box
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Primary Relief Valve
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Tank Pressure Gauge
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Fill Vent Fitting
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Excess Flow Valve
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Fuel Shutoff Valve (liquid)
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Fill Check Valve
Fig. 1, LNG Tank Plumbing Components
- Inspect the fuel level sender wiring harness for signs of loose connections or damage. Look for cracking or signs of moisture intrusion.
- Inspect the fuel level sender box ( see Fig.) for signs of leaks or damage. Ensure that the retainer clips are installed on the mounting ears.
- Inspect all connectors and wiring for signs of loose connections, damage, or chafing.
- Turn the ignition switch to the ON position and check for fuel gauge response.
- Repair or replace any damaged fuel gauge components.