19

16
14

Figure 6. Fuel management module (FMM) components (refer to Table 5).

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Table 5. Fuel management module (FMM) components (refer to Figure 6).

Item
1
2
3
4
5
6
7
8*
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23*
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

QTY

1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1

Description
Fitting, male connector
Fitting, male adapter
Dust cap, rubber, NGV1/defuel receptacle
Receptacle, CNG NGV1/defuel receptacle
Receptacle, CNG transit (fast) fuel fill
Dust cap, rubber, transit fuel fill
Fuel fill manifold, with remote fuel fill port
Fuel fill manifold, standard
Fitting, adapter
Tube, HP fuel, Manifilter to regulator
Fitting, straight union
Fitting, 90-degree adjustable elbow
Fitting, adapter, straight
Fitting, JIC, 90-degree elbow, large
Fitting, JIC, 90-degree elbow, small
Fitting, JIC, straight
Defuel valve
Pressure regulator
Supply solenoid valve (SSV)
Pressure transducer, HP fuel filter
ASM, Manifilter
1/4-turn manual shut off valve
Spacer, 1/4-turn manual shut off valve
High-pressure fuel filter element
P-clip, 3/8-in., rubber clamp
ASM, Tube, PRD, regulator to vent
Tube, HP fuel, Manifilter to 1/4-turn manual shut off valve
Tube, HP fuel, Manifilter to HP gauge
Tube, LP fuel, regulator to LP gauge
Tube, HP fuel, bleed valve to manifold
Cap, PRD vent, heat shrink
Check valve, 6000 psi, CNG, with fittings
Gauge, high-pressure, 0-6000 psi
Gauge, low-pressure, 0-200 psi
Fitting, connector
Bleed valve, Manifilter
Vent stack assembly
Face plate, FMM (faceplate shown is for optional Smart Gauge; standard faceplate is similar)
Cover, FMM, rear
Auxiliary remote fill panel (optional)

*Not shown

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3. Fuel System Components and Specifications
3.1. Fuel Specifications
Fuel quality is crucial to maintaining engine
performance characteristics, life expectancy, and
emission standards. CNG fuel must meet or exceed
Cummins CES 20067 requirements.
Failure to meet fuel requirements may result in
poor engine performance and damage that is not
covered under warranty.

FMM components and connections inside the fill
panel. Figure 9

1
2

3.2. Superstructure
The fuel system structures and components are
designed to meet or exceed all safety and vehicle
standards. The systems are shipped as complete
units ready to be bolted on and connected for turnkey operation. Figure 7

4

7

5

6

8

3
Figure 9. FMM components (rear view):
(1) high-pressure fuel line to cylinders, (2) highpressure Manifilter, (3) remote fill panel (optional);
(4) solenoid valve, (5) pressure regulator, (6)
regulator coolant ports, (7) defuel valve, (8) lowpressure fuel line connection.

An optional remote fill panel connects to a special
manifold on the rear of the FMM for ease of fueling.
Figure 10

1

Figure 7. Eight-cylinder roof mounted CNG storage system.

3.3. Fuel Management Module
The fuel fill panel control interface (Figure 8) is
accessible by opening the fill panel access door at
the rear passenger side of the vehicle.
1

2

4

3

5
4

5

2
6
Figure 8. FMM faceplate components.
(1) 1/4-turn manual shut off valve, (2) transit (fast) fill receptacle,
(3) high-pressure gauge, (4) NGV1 fuel fill / defuel receptacle, (5)
low-pressure gauge, (6) Smart Gauge (if equipped).

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3
Figure 10. Remote fill option components.
(1) tube, remote fill to FMM manifold. (2) dust cap,
(3) transit (fast) fill receptacle,
(4) remote fill bracket, (5) remote fill manifold.

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3.4. Filters

3.4.2. Low-pressure Filter

3.4.1. High-pressure Filter

The low-pressure (LP) coalescing filter is located
downstream of the 1/4-turn manual shut off valve,
high-pressure filter, and regulator. The LP filter
removes residual contaminants and oil from the fuel
before it enters the engine.

The high-pressure (HP) coalescing fuel filter or
Manifilter is located downstream of the manifold
and main shut off valve and upstream of the supply
solenoid valve. The Manifilter purifies fuel by
removing moisture and contaminants. Figure 11
High-pressure filter specs
Efficiency: 10 microns
Element Change Frequency:
Severe Duty Every 15,000 miles (24,000 km)
OR
Every 1,000 hours / 9 months
whichever comes first
Normal Duty Every 30,000 miles (48,000 km)
OR
Every 1,000 hours / 9 months
whichever comes first
1

Low-pressure filter specs
The LP filter is sealed with a lubricated gasket
and includes a drain cock at the bottom.
Operating range: -43°F to +250°F
-42°C to +121°C
Efficiency:
 99.9% for 0.3 micron liquid droplet
 100% for 25 micron particles
Mounting type: Spin-on, 1-1/2-16 UN-2B thread
1

2

3
4

3

6

Figure 12. Low-pressure fuel filter components.
(1) LP filter head; (2) LP filter element, (3) drain cock.

5

2

7
8
9
Figure 11. High-pressure filter components:
(1) Manifilter housing, (2) Manifilter bowl O-ring,
(3) HP filter element O-ring, (4) HP filter element housing, (5) HP
filter element, (6) element base, (7) Manifilter bowl, (8) drain plug
O-ring, (9) hex head drain plug.

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3.5. Supply Solenoid Valve (SSV)

3.6. Pressure Regulator

Located in the FMM between the Manifilter and the
pressure regulator, the supply solenoid valve (SSV)
controls CNG flow. Figure 13

Located adjacent to the supply solenoid valve in the
FMM, the pressure regulator is the dividing point
between the high-pressure and low-pressure sides
of the fuel system.

The supply solenoid valve generates heat during
operation and may cause burns on contact.

Figure 13. Supply solenoid valve (SSV).

3.5.1. Supply Solenoid Valve (SSV) Principles of
Operation

The pressure regulator reduces CNG up to 3600 psi
(250 bar) down to a pressure usable by the engine
typically around 125 psi (8.61 bar). Figure 14
Pressure regulator specs
Set point: 125 psi (8.61 bar) outlet @ 3600 psi
(250 bar) inlet pressure
PRD: 200 ± 40 psi (13.7 bar ± 2.75 bar) crack
pressure
Max. pressure: 3600 psi (250 bar)
Min. pressure: 250 psi (17.2 bar)
Gas flow rate: 0-110 lb/hr nominal
Coolant temperature range: -40°F to +257°F
-40°C to +125°C

De-energized: The supply solenoid valve acts
directly by utilizing an armature and a pilot as
opposed to a plunger. Pressure from the inlet port
flows through the pilot guide surrounding the
armature, the pressure is then stopped by the pilot
at the orifice.
Energized: The supply solenoid valve operates
using 24V DC from the onboard power supply. The
armature is forced upwards and lifts the pilot from
the seat of the orifice allowing pressure to flow from
the inlet port to the outlet port.

Figure 14. Pressure regulator.

3.7. Cylinders
The eight roof mounted cylinders are standard Type
4 CNG cylinders which are designed, manufactured,
inspected, and qualified in accordance with NGV-2
2019.
Total system water volume is noted on the FMM face
plate.
Cylinder specs
Service pressure: 3600 psi @ 70°F
250 bar @ 21°C
Service life: Refer to cylinder manufacturer
label or marking

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3.8. Valves

3.8.4. 1/4-turn Manual Shutoff Valve

3.8.1. Bleed Valve

The 1/4-turn manual shutoff valve located on the
FMM face plate is also known as the “main” or
“emergency” shutoff valve.

The bleed valve (1) enables safe venting of system
pressure and is located on the Manifilter (3). Figure
15
Bleed valve specs
Flow coefficient: 0.25
Temperature rating: -4°F to +450°F
-20°C to +232°C

When in the CLOSED/OFF position, the 1/4-turn
manual shutoff valve prevents the flow of CNG past
its location in the fuel system. Turned the OPEN/ON
position, the 1/4-turn manual shutoff valve permits
fuel to flow from the cylinders to the FMM
components. As its name implies, turning the 1/4turn manual shutoff valve 90-degrees by hand
changes it from OPEN to CLOSED and reversing the
direction of rotation restores it to the OPEN position
for normal operation. Figure 18
1/4-turn manual shutoff valve specs
Temperature rating: -40°C to 93°C
-40°F to 200°F

2
1
3
Figure 15. Bleed valve location.
(1) Bleed valve, (2) nut, (3) Manifilter.

Figure 18. 1/4-turn manual shutoff valve.

3.8.2. Check Valve
Check valves located downstream the fill
receptacles in the FMM prevent CNG from following
out of the system. Figure 16

3.8.5. Manual Cylinder Valve
On fuel system p/ns 25518000, 25520000, and
25522000, each cylinder is equipped with a
manually operated shutoff valve to isolate CNG from
the rest of the fuel system. Figure 19a
Manual cylinder valve specs
Service pressure: 3600 psi (250 bar)
Working temperature: -40°F to +185°F
-40°C to +85°C

Figure 16. Check valve.

3.8.3. Defuel Valve
Located inside the FMM. the defuel valve allows fuel
to be removed from the system via the defuel
receptacle. Figure 17

3

2

1

Figure 17. Defuel valve.

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Figure 19a. Manual cylinder valve (1), shutoff knob (2), valve PRD
(3).

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3.8.6. Electric Solenoid Cylinder Valve

3.9.2. Remote PRD

On fuel system p/ns 25510000, 25521000, and
25523000, each cylinder is equipped with an electric
solenoid operated valve. Each electric solenoid
valve is equipped with a manual shutoff knob to
isolate CNG contained within the cylinder from the
rest of the fuel system. Figure 19b

Each cylinder is equipped with multiple remote
PRDs which connect to the respective cylinder plug
end via several live PRD supply tubes. Figure 20a

Electric solenoid cylinder valve specs
Service pressure: 3600 psi (250 bar)
Working temperature: -40°F to +185°F
-40°C to +85°C

Remote PRD specs
Operating temperature: -40°F to 180°F
-40°C to +82°C
Service pressure: 3626 psi at 59°F
250 bar at 15°C
Working pressure: 4467 psi at 180°F
308 bar at 82°C
Activation temperature: 230°F / 110°C

2
3
1
Figure 20a. Remote PRD.

PRD supply lines are always pressurized when gas
is present in the system.
Figure 19b. Electric solenoid cylinder valve (1), manual shutoff
knob (2), valve PRD (3).

Plug end
1

3.9. Pressure Relief Devices (PRDs)
3.9.1. Valve PRD
Cylinder valves are fitted with a PRD on each valve
which connect to PRD vent tubes. Figures 19a and
19b
Valve PRD specs
Operating temperature: -40°F to 180°F
-40°C to +82°C
Service pressure: 3626 psi at 59°F
250 bar at 15°C
Working pressure: 4467 psi at 180°F
308 bar at 82°C
Activation temperature: 230°F / 110°C

Valve end

1

Figure 20b. Remote PRD (1) locations. Note: Manual cylinder
valve system shown; electric solenoid valve system similar.

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3.10. Fuel Fill and Defuel Receptacles

3.10.2. Remote fuel fill receptacle (optional)

3.10.1. Standard fuel fill & defuel receptacles

Vehicles equipped with an FMM incorporating a
remote fuel fill panel include an additional transit
(fast) fill receptacle matching the specifications
above. Figure 22

The FMM face plate contains a transit or “fast” fill fuel
receptacle (1) and an NGV1 receptacle (2) used
exclusively for defueling. Figure 21
Fuel fill and defuel receptacle specs

5

Design pressure: 5000 psi (350 bar) max.
Flow rate, transit fill: 5000 SCFM (8043 nm3/hr)
@ 3000 psi (207 bar)
Flow rate, NGV1: 1500 SCFM (145 nm3/hr) @
3000 psi (207 bar)
Temperature range: -40°F to 250°F
-40°C to 121°C

6
Figure 22. Optional remote transit fuel fill panel:
(5) transit (fast) fill receptacle,
(6) transit (fast) fill receptacle dust cap.

1
3

Dust cap (6) must reinstalled immediately after
receptacle use. Figure 22

2