Mityvac MV5545 - Appendix D

Page Number - 40
*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 Peak Flow Potential Causes
1 Normal Normal
Less than
10% below
idle pressure
Normal
50% to
100% higher
than spec
Normal
.7 to 1.0 GPM
(2.5 to 4.0 LPM)
Fuel system is
operating normally
2 Normal Low
Greater than
10% below
idle pressure
Normal
50% to
100% higher
than spec
Low
Less than .7
GPM (2.5 LPM)
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
.7 to 1.0 GPM
(2.5 to 4.0 LPM)
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
.7 to 1.0 GPM
(2.5 to 4.0 LPM)
5 Low Low
Less than
maximum
fuel volume
requirement*
Low
Less than
50% higher
than spec
Low
Less than .7
GPM (2.5 LPM)
Fuel Rail