There are two procedures that will allow a technician to identify a leaky pressure limiting valve (PLV). A defective PLV can cause the following conditions:
- Instable rail pressure (Temperature Test and Flow Test)
- Long crank times (Temperature Test and Flow Test)
- Codes related to rail pressure deviation (Temperature Test and Flow Test)
- No start condition (loose or leaking significantly) (Flow Test)
A flow test is required if a no start condition is occurring and the PLV is main suspect.
DD15 PLV Leakage Temperature Test
Test as follows:
- Start the engine.
- Use an infrared temperature gun (1), measure the surface temperature of the fuel rail (2) between cylinders #4 and #5.
- Take a second measurement at the solid PLV line just above the connection on the fuel filter module (3).
- Compare the two values to the examples in the trend chart below.
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- If the PLV is not opening , the surface temperature at the PLV line will be less than the rail surface temperature.
- If the PLV is opening , the surface temperature at the PLV line will be greater than the rail surface temperature
Pressure Limiting Valve Trend Data Examples Component Normal PLV (cold start)
Normal PLV (after drive cycle)
Normal PLV (after drive cycle)
Leaking PLV Fuel Rail Surface Temperature 82-89°F 187°F 168°F 90-97°F PLV Line Surface Temperature 76-77°F 160°F 155°F 105-108°F -
DD15 PLV Leakage Flow Test
Test as follows:
- Remove PLV line to the fuel filter module.
- Install clear hose and fitting J-48708-4 from J-48708 kit.
- Cap fitting at module.
- Connect the opposite end to the J-48708 tank.
- Crank or start engine and note the return flow to the tank.
- If return fuel is noted, replace PLV.
- If no return flow is noted, go to next step.
- Sweep engine speed from idle to 1800 and note the return flow to the tank.
- If return fuel is noted, replace PLV.
- If no return flow is noted, PLV is not causing the error condition.
