RAM 3500 Truck 2WD L6-5.9L DSL Turbo VIN C (2003)
log the fuel pressure set point and actual fuel pressure. A good system will have actual fuel pressure that is +/- 500 PSI from the set pressure.
(Example: If the fuel pressure set point at idle is 6500 PSI, the actual fuel pressure on a good system is expected to be between 6000 - 7000 PSI).
If fuel pressure variation is excessive, an audible surge will be present. If the variation is severe, a slight engine speed variation may also be
noticed. Does the actual fuel rail pressure fluctuate more than +/- 500 PSI?
a.
Yes >> Go to Step # 3.
b.
No >> Go to Step # 8.
NOTE:
A loud "knock" and black smoke that exists with an actual fuel pressure drop may be an injector issue and should be identified using the single
cylinder cut out test.
3.
Verify proper low pressure fuel supply to the injection pump: Perform the appropriate fuel supply system flow test. NOTE: This procedure may be
slightly different depending on if the vehicle has an engine mounted transfer pump or the in-tank transfer pump. In a good low pressure fuel
system, fuel flow of 560 mL in 10 seconds or better is expected for model years 2003 and early 2004. The fuel volume for the model years late
2004 through 2007 is 590mL in 10 seconds. Be sure there is no air in the system. Is the low pressure fuel supply sufficient?
a.
Yes >> Go to Step # 4.
b.
No >> Repair the low pressure fuel supply system. Refer to the detailed diagnostic information available in TechCONNECT under: Service
Info tab > 9 - Engine> Diagnosis & Testing > Fuel Lift Pump - Diesel. >> Go to Step # 15.
4.
Test for high injector return flow: Refer to the detailed diagnostic information available in TechCONNECT under: Service Info tab > 9 - Engine >
Diagnosis and Testing > Injector Return Flow Test. Do the injectors pass the "Injector Return Flow Test"?
a.
Yes >> go to Step # 6.
b.
No >> go to Step # 5.
5.
If the injector return from any cylinder(s) is deemed excessive:
a.
Check HPC tip for damage, replace HPC if damaged. Refer to the detailed service information available in TechCONNECT under: Service
Info tab > 14 - Fuel System > Fuel Injection > Fuel Injector > Removal/Installation. >> Go to Step # 15.
b.
If HPC tip is undamaged, replace the injector and HPC. Refer to the detailed service information available in TechCONNECT under:
Service Info tab > 14 - Fuel System > Fuel Injection > Fuel Injector > Removal/Installation. >> Verify that a quality fuel filter is used. >>
Go to Step # 15.
6.
Verify high pressure pump output volume: Remove the high pressure fuel line from the high pressure pump outlet port to the fuel rail. Connect a
suitable hose to the high pressure outlet port of the high pressure pump and route it to a graduated container. Disconnect the Electronic Fuel
Control Actuator. Crank the engine until fuel exits the hose. NOTE: With the discharge line routed to atmosphere, fuel will discharge at 0 PSI.
Crank the engine for three 10 second intervals, pausing to allow the starter to cool between each crank event. High pressure pump output volume
must be greater than 70 mL in 30 seconds. Is the high pressure pump output flow sufficient?
a.
Yes >> go to Step # 7.
b.
No >> Replace the high pressure pump. Refer to the detailed service information available in TechCONNECT under: Service Info tab > 14
- Fuel System > Fuel Injection > Fuel Injection Pump. >> Go to Step # 15.
7.
Electronic Fuel Control Actuator (FCA): Replace the Electronic Fuel Control Actuator. Refer to the detailed service information available in
TechCONNECT under: Service Info tab > 14 - Fuel System > Fuel Injection > Fuel Injection Pump. >> Go to Step # 15.
8.
Verify High Pressure System Is Functioning Normally: Using the appropriate scan tool watch the fuel rail pressure set point. Does the fuel rail
pressure set point fluctuate at idle?
a.
Yes >> Check the vehicle for signs of parasitic load causing the ECM to adjust fuel pressure set point.
b.
No >> Go to Step # 9.
9.
Idle speed fluctuation: Using the appropriate scan tool watch idle speed. Compare the idle speed shown on the scan tool to the reading on the
tachometer. Does the idle speed on the scan tool fluctuate more than 20 RPM while the engine is at idle?
a.
Yes >> Go to Step # 10.
b.
No >> Investigate fuel quality. Look for evidence of fuel contamination. Investigate for aftermarket performance devices.
