F1 Compressed Natural Gas Vehicle

  • Vehicle Inspection for Condition, Suitability, and Compliance
  • Equipment Suitability Installation and Inspection
  • Leak Testing and Repairs
  • Emissions, Performance Verification, and Adjustments
  • System Diagnosis, Maintenance, and Repair
  • General Cylinder Safety and Maintenance

Compressed Natural Gas Vehicle

A. Vehicle Inspection for Condition, Suitability and compliance (5 questions)

1. Inspect vehicle for fitness (weight, mileage, applicable emissions standards, and safety standards).

2. Analyze engine performance; determine needed repairs.

3. Verify size, weight and capacity of compressed natural gas cylinder(s).

4. Inspect for proper location and mounting of compressed natural gas cylinders and fuel system components.

5. Inspect for location, condition and compliance of venting system(s).

B. Equipment Installation and Inspection (8 questions)

1. Visually inspect fuel storage cylinders and system components prior to installation.

2. Install fuel storage system; secure with recommended brackets, isolators, reinforcements, and fasteners; inspect fuel storage system.

3. Install/inspect regulator assembly(ies) and coolant lines as required.

4. Install/inspect underhood fuel delivery system components.

5. Install and connect/inspect system wiring.

6. Install/inspect electrical and electronic components.

7. Install/inspect instrument panel components.

8. Install / inspect fuel lines, clamps, filters, and fittings.

9. Install / inspect valves, pressure relief devices, venting systems, lines and fittings; secure with recommended fasteners.

10. Install / inspect fuel fill receptacle(s) and check valve(s).

11. Install / inspect required labels.

12. Complete system documentation as required.

C. Leak Testing and Repairs (6 questions)

1. Check for low and high-pressure natural gas leaks; repair as needed.

2. Pressurize cylinders with natural gas.

3. Check for coolant leaks; repair as needed.

4. Check venting system integrity as required.

D. Emissions, Performance Verification and Adjustments (11 questions)

1. Check base ignition timing; adjust where applicable.

2. Check regulator(s) pressure(s); adjust where applicable.

3. Check mixture settings; adjust where applicable

4. Verify Power Train Control Module(s) (PCM) Calibration.

5. Check operation of electronic components.

6. Check operation of fuel gauge; make repairs as required.

7. Perform emission tests; make repairs and document where applicable.

8. Road test vehicle for acceptable driveability; check starting/restarting abilities.

9. Check manual and automatic fuel changeover operation (bi-fuel vehicles).

10. Check fuel system for abnormal noises.

11. Verify gaseous fuel management operation.

E. System Diagnosis Maintenance and Repair (16 questions)

1. Interpret and verify operational complaint; determine needed repair.

2. Visually inspect gaseous fuel system components; determine needed repairs. 

3. Retrieve and interpret Diagnostic Trouble Codes (DTC) through the use of recommended PC based software, DMM, and/or scan tool.

4. Diagnose driveability and emissions problems related to the ignition system; determine needed repairs.

5. Diagnose driveability and emissions problems related to fuel and air induction systems, and exhaust systems; determine needed repairs.

6. Diagnose driveability and emissions problems related to electronic engine controls; determine needed repairs.

7. Check vacuum/electrical/electronic component operation; repair or replace as needed.

8. Check gaseous fuel delivery system pressures, component operation; repair or replace as needed.

9. Remove and/or replace fuel lines, manual and electrical valves, fittings, and pressure relief devices.

10. De-fuel CNG system.

11. Check for signs of fuel contamination; inspect, replace and/or service fuel system filters as required.

F. General Cylinder Safety and Maintenance (9 questions)

1. Visually inspect fuel storage cylinder(s), shields and mounting.

2. Remove and replace cylinders; de-fuel according to recommended procedures; replace shields, brackets, and hardware as required.

3. Handle and store cylinders in accordance with recommended procedures.

4. Interpret cylinder label information; determine necessary action.

5. Inspect pressure relief devices (PRD) and related hardware; determine necessary action.

6. Inspect condition and operation of cylinders / tank valves; determine necessary action.

7. Decommission cylinders according to recommended procedures.