Engine Controls - Basic Diagnostic Procedures - Trucks - Diesel: Diagnosis Dodge Cab & Chassis R3500

VISUAL INSPECTION

1. Check Water-In-Fuel (WIF) sensor electrical connector for corrosion, damaged terminals or wiring and tight fit on engine wiring harness. WIF sensor is located in bottom of fuel filter/water separator. (Scheme 65)
2. Check for water in fuel filter/water separator by placing drain pan below drain tube at fuel filter/water separator. (Scheme 65) With engine not running, rotate handle on drain valve forward, toward front of vehicle to OPEN position. Drain valve is located near top of fuel filter/water separator. Drain water from fuel filter/water separator.
3. If no water exists and a clean flow of diesel fuel exists, rotate handle on drain valve back to CLOSE position. Go to next step. If water exists, allow water to drain until clean flow of diesel fuel exists. Rotate handle on drain valve back to CLOSE position. Go to next step.
4. Verify fuel filter/water separator has been serviced according to proper service schedule. See SERVICE & ADJUSTMENT SPECIFICATIONS - RAM PICKUP article. NOTE: The Yellow disc in Filter Minder (FM) may reach Red zone if air intake is restricted or air filter has become wet during heavy rain or snow. If air filter has become wet, allow air filter to dry during normal engine operation and reset FM by pressing rubber button on top of FM.
5. Check color of FM. FM is located on top cover on air filter housing, just above air filter. DO NOT remove air filter from air filter housing for inspection. If Yellow disc in FM has reached Red zone, remove and inspect air filter. (Scheme 66) If air filter is dirty, replace air filter and reset FM by pressing rubber button on top of FM.
6. Ensure intercooler inlet and outlet duct clamps are tight and front of intercooler is not restricted with dirt. (Scheme 67)
7. Ensure connections on both batteries are tight and not corroded. Ensure the three 32-pin connectors are fully engaged on Powertrain Control Module (PCM). PCM is located on firewall at passenger's side rear corner of engine compartment. see scheme 2
8. Check for loose, defective or corroded connections at intake manifold air temperature sensor. (Scheme 68)
9. Ensure electrical connections on intake manifold air heater relays and intake manifold air heater are tight and not corroded. Intake manifold air heater relays are mounted on inner wheelwell, below driver's side battery. (Scheme 69) Intake manifold air heater is located between air inlet housing and intake manifold cover. (Scheme 70) NOTE: Restricted low-pressure fuel lines from fuel tank to fuel transfer pump, fuel heater and fuel filter/water separator may cause starting problems and prevent engine from accelerating. Restricted high-pressure fuel lines from fuel injection pump to fuel injector may cause starting problems, poor engine performance and excessive Black smoke.
10. Check all fuel supply and returns lines for damage, kinking or leakage. Check throttle linkage for binding. Check for a stretched or disconnected throttle return spring.
11. Ensure all ground connections are tight and free of corrosion. Ensure accessory drive belt is not damaged or slipping. Check for loose or defective electrical connection on Camshaft Position (CMP) sensor. see scheme 1
12. On A/T models, ensure all electrical connectors are clean and properly connected to electrical plugs on transmission case. On all models, check for loose or defective electrical connections on starter and starter solenoid.

Scheme 65

Scheme 66

Scheme 67

Scheme 68

Scheme 69

Scheme 70

Diagnosing Leaks

Note. A leaking fuel injector may cause a rough idle, Black smoke, poor engine performance, poor fuel economy and fuel knock. Since a leaking high-pressure fuel line may cause the same symptoms, check for leaking high-pressure fuel line before checking fuel injector.

1. To check for a leaking high-pressure fuel line, start engine and allow engine to idle. Inspect high-pressure fuel lines and connections for signs of fuel leakage by placing cardboard over high-pressure fuel line and connection. Note if leak is being detected by fuel being sprayed onto the cardboard. If leak exists, repair leak by tightening high-pressure fuel line nut to 30 ft. lbs. (40 N.m) or replacing high-pressure fuel line as necessary. If high-pressure fuel line is replaced, bleed air from fuel system. See «BLEEDING AIR FROM FUEL SYSTEM»(ref-97352-S12672373912001052200000) . If no leaks are found, go to next step.
2. To check for defective fuel injector using scan tool, connect scan tool to Data Link Connector (DLC). Start engine and idle engine. Using scan tool, disable each cylinder and listen for RPM drop. If fuel injector is operating properly, engine idle speed should decrease when each fuel injector is disabled. Repeat procedure on each fuel injector. Go to step 4 .
3. To check for defective fuel injector without scan tool, start engine and idle engine. Loosen high-pressure fuel line nut at fuel injector and listen for a decrease in engine speed. Tighten high-pressure fuel line nut to 18 ft. lbs. (24 N.m). If fuel injector is operating properly, engine idle speed should decrease when high-pressure fuel line nut is loosened. Repeat procedure on each fuel injector. Go to next step.
4. If engine idle speed does not decrease, fuel injector is defective and should be removed and tested with a diesel fuel injector tester. Go to next step.
5. Remove suspect injector. See FUEL INJECTOR under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - RAM PICKUP - DIESEL article. Test injector with a diesel fuel injector tester. Follow tester instructions. Replace fuel injector if fuel injector opening (pop) pressure is not 4250-4750 psi (299-334 kg/cm 2 ). Replace injector if any leaks are noted at 291 psi (20 kg/cm 2 ) less than opening (pop) pressure. Inspect injector for burrs, cracks, wear and plugging. Check spray pattern. If any problems are noted, replace injector.

Diagnosing Restrictions

Restricted or kinked low pressure fuel line symptoms will include starting problems, low power and/or White fog from exhaust. To test for low pressure fuel line restrictions, go to FUEL TRANSFER PUMP PRESSURE TEST under FUEL TRANSFER PUMP. After repairing low pressure fuel line, bleed air from system. See BLEEDING AIR FROM FUEL SYSTEM .

Restricted or kinked high-pressure fuel line symptoms will include starting problems, poor engine performance, engine misfire and/or White smoke from exhaust. Visually inspect high-pressure fuel lines. Replace kinked, restricted or damaged high-pressure fuel line(s) as necessary. After replacing high-pressure fuel line(s), bleed air from system. See BLEEDING AIR FROM FUEL SYSTEM . If fuel lines are okay, check injectors.

Remove suspect injector. See FUEL INJECTOR under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - RAM PICKUP - DIESEL article. Test injector with a diesel fuel injector tester. Follow tester instructions. Replace fuel injector if fuel injector opening (pop) pressure is not 4250-4750 psi (299-334 kg/cm 2 ). Inspect injector for burrs, cracks, wear and plugging. Check spray pattern. If any problems are noted, replace injector.

Fuel Transfer Pump Preliminary Inspection

1. Check for restricted or leaking fuel supply line to fuel transfer pump or fuel return line located on driver's side of engine. (Scheme 71) Repair fuel supply line or fuel return line if restricted or leaking.
2. Check for fuel leaking from fuel transfer pump. Replace fuel transfer pump if fuel is leaking. If fuel is not leaking from fuel transfer pump, check fuel transfer pump output pressure. See «FUEL TRANSFER PUMP PRESSURE TEST»(ref-97352-S21886946582001050200000).

Scheme 71

Fuel Transfer Pump Pressure Test

Note. Fuel transfer pump operates at 2 different pressures. After performing pressure test, perform pressure drop test.

1. Remove protective cap from fuel pressure inlet test port. see scheme 9 Install Fuel Pressure Test Gauge (6828) at inlet port. To prevent engine starting, remove fuel injection pump relay, located in power distribution center. see scheme 10
2. Crank engine over while observing gauge. Inlet pressure should be 5-7 psi. Install fuel injection pump relay. Start engine. Inlet pressure should be 10 psi. DTC may set when relay is removed. Using a scan tool, clear DTC. Proceed to «FUEL TRANSFER PUMP PRESSURE DROP TEST»(ref-97352-S41398319232001050200000).

Fuel Transfer Pump Pressure Drop Test

1. Remove protective cap from fuel pressure outlet test port. see scheme 9 Install Fuel Pressure Test Gauge (6828) at outlet port. Start engine and allow engine to idle. Record fuel pressure.
2. Fuel pressure at outlet fuel pressure test port should not be more than 5 psi (.35 kg/cm 2 ) less than fuel pressure obtained at inlet fuel pressure test port. Shut engine off. If fuel pressure drop is not as specified, replace fuel filter. Remove fuel pressure gauge and reinstall protective caps.

Fuel Transfer Pump Fuel Supply Restriction Test

Note. Due to very small vacuum specifications, use a scan tool and Periphal Expansion Port (PEP) module with 0-15 psi transducer to perform following test.

Ensure transfer pump pressure is okay before performing following test. See FUEL TRANSFER PUMP PRESSURE TEST . Disconnect fuel supply line-to-fuel transfer pump quick connect fitting at left rear of engine. Carefully remove plastic clip from pump inlet and install in end of fuel supply line. Install 3/8" Adapter Hose (6631 ) between fuel supply line and pump inlet. Install transducer from PEP module to "T" fitting on adapter. Connect scan tool. Start engine. Check vacuum reading with engine at full throttle with no load. If vacuum reading is less than 6 in. Hg, check for fuel supply air leaks. If vacuum reading is 6 in. Hg or more, check fuel line for damage, dents and kinks. Repair as necessary. If no problem is found, remove fuel module from fuel tank and check for obstructions. Repair as necessary.

Fuel Transfer Pump Fuel Supply Air Leak Test

Note. A 3' section of 1/4" I.D. clear tubing is required for the following test.

Clean area around filter inlet fitting test port. see scheme 9 Using tire core valve removal tool, remove core valve from fitting test port. Attach clear hose with a clamp to fitting. Place other end of hose in a fuel container. Turn ignition switch to START position, then release to RUN position without starting engine. Fuel transfer pump should run for 25 seconds. After hose has been purged, watch for any air bubbles in hose. If no bubbles exist, system is okay. If bubbles exist, check fuel line, fittings and fuel module in tank. Repair as necessary.