Page Number - 30
Form 824262
*See Appendix A for maximum engine fuel volume requirement
Inlet strainer/sock
ECM/PCM
Pressure Transducer/Sensor
Fuel Filter
Fuel Pump
Fuel Supply Line
Appendix D – Returnless (Electronically Regulated) Fuel System Diagnostic Guide
Results
Scenario
Idle
Pressure
Peak Demand Pressure
Peak Pressure
(CLOSED)
Peak Flow
(BYPASS)
Potential Causes
1
Normal
Normal
Less than
10% below
idle pressure
Normal
50% to 100%
higher than
spec
Normal
2.5 to 4.0 LPM
(.7 to 1.0 GPM)
Fuel system is
operating normally
2
Normal
Low
Greater than
10% below
idle pressure
Normal
50% to 100%
higher than
spec
Low
Less than
2.5 LPM
(.7 GPM)
Blocked fuel filter,
inlet strainer or
pinched supply line
3
Low
Low
Greater than
10% below
idle pressure
Low
50% to 100%
higher than
spec
Normal
2.5 to 4.0 LPM
(.7 to 1.0 GPM)
Electronic control
failure, failing fuel
pump or insufficient
power supply
4
High
High
Less than
maximum
fuel volume
requirement*
High
50% to 100%
higher than
spec
High
2.5 to 4.0 LPM
(.7 to 1.0 GPM)
5
Low
Low
Less than
maximum
fuel volume
requirement*
Low
Less than
50% higher
than spec
Low
Less than
2.5 LPM
(.7 GPM)
Fuel Rail
