DSM.0165 Ver. 2.0  April 26, 2023

Diagnostic, service, maintenance, and inspection manual for 287-series ProRail® side mount (SM) compressed natural gas (CNG) fuel systems equipped with Marathon pressure regulator and Blue iQ™.

Description and Operation Overview 


Service Intervals

Depressurization Procedure

Defuel Procedures

Vent to Atmosphere

Fuel Transfer

Excess Flow Valve Reset Procedure

PRD Vent Cap Replacement

Manifilter Element Replacement

Inspection Types and Intervals

Initial Delivery Inspection

Driver Daily Checklist

Six Month Inspection

Cylinder Inspection

Fuel System Inspection

Bushing Ring and Isolator Inspection

Fuel Hose Inspection

Symptom-based Diagnostics

No Crank, No Start Diagnostic

Crank, No Start Diagnostic

Drivability Diagnostic

OEM Fuel Gauge Inoperative Diagnostic

Blue iQ™ Fault Code Diagnostics

Blue iQ™ Fault Code List

Blue iQ™ Fault Code Diagnostic Procedures

Repair and Replacement Procedures

Blue iQ™ Smart Gauge 

Fuel Management Module (FMM) Components

Fuel System Control Module (FSCM)

1/4-turn manual shutoff valve 

Standard NGV1 fill receptacle or fast fill receptacle 

Fuel receptacle cover 

Reed switch 

Kill cap

High-pressure (HP) fuel gauge or low-pressure (LP) fuel gauge 

Manifilter assembly

Supply solenoid valve (SSV)

Supply solenoid valve (SSV) coil

Pressure regulator (Marathon extended range)

Pressure / temperature transducer

Bleed valve 

Defuel valve

Defuel receptacle


Fuel Storage System Components


Cylinder composite repair

Cylinder boss repair

Cylinder valve

Cylinder plug

Remote PRD

Cylinder neck mount block - fixed (valve) end

Cylinder neck mount block - sliding (plug) end

Cylinder neck mount block bushing



Fuel system cover

Wiring and Harness

CNG Special Service Tools

Removing a Vehicle from Service

Glossary of Terms

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