SPN 1077 FMI 31 is the Detroit DD Series fault-code troubleshooting sheet that documents a rail pressure deviation, where the Motor Control Module (MCM) sets the code when rail pressure deviation is greater than 200 bar for eight seconds on the Motor Control Module engine platform. This 8-page reference reproduces the fault-code identification and the factory decision tree so a technician can diagnose the concern before replacing parts.
Official document details — SPN 1077 FMI
| Brand | Detroit |
|---|---|
| Model coverage | Detroit DD Series (EPA 2007-Current) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | FMI 31 under SPN 1077 (ALL YEARS) |
| Source | Detroit fault-code literature via TruckFaultCodes.com, © 2017 |
| Pages | 8 |
| Format | |
| Language | English |
SPN 1077 FMI 31 fault description
The eight-page procedure walks through fuel-system integrity testing in a fixed order. It begins with fuel level and fuel-contamination checks and a scan for related fuel-filter, water-in-fuel and sensor codes. It then reviews Pressure Limiting Valve (PLV) open counts, runs the Automatic Fuel System Integrity Check (FSIC), and evaluates rail-pressure bleed-off time and Idle Speed Balance values before injector, PLV or high pressure fuel pump replacement.
The SPN 1077 FMI 31 sheet identifies the following likely causes and check points:
- External fuel leakage between the high pressure pump and injectors
- Pressure limiting valve internal leakage
- Fuel filter integrity or fuel supply issues
- High pressure pump internal failure or injector leakage
Document table of contents
- Description and enabling conditions
- Service tools used in the procedure
- Fuel level and contamination checks
- Pressure Limiting Valve open counts
- Automatic Fuel System Integrity Check (FSIC)
Service tools referenced
- J-48876 primer port test gauge
- J-48704 high pressure fuel rail caps
- J-48706 fuel diagnostic gauge set
- DDDL 7.06 sp2 or higher
Applicable truck models
This troubleshooting sheet applies to Detroit DD Series engines built from EPA 2007 to current that use the Motor Control Module (MCM) and Common Powertrain Controller architecture. Confirm the engine’s emissions family and calibration against the manufacturer’s official documentation at the Detroit engine website before repairs.
Who needs this SPN 1077 FMI 31 manual
Heavy-duty diesel technicians, fleet shops and mobile mechanics who retrieve this code on a Detroit DD engine need this manual to follow the factory decision tree instead of guessing. It is written for anyone using DDDL or an equivalent diesel diagnostic tool who wants the exact test values before condemning a component.
The full 8-page PDF of this procedure is available in the DiagTechPro manuals library; a free account is required to download.
Related manuals library
