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Hard/No Start Diagnostic Checklist for '94.5-97 F-series 7.3L
1. Visual Engine/Chassis Inspection
Purpose: This is a visual inspection to check the general condition of the engine and look for obvious causes of hard start or no start conditions.
Recommended Procedure:
Inspect fuel system including fuel tank and fuel lines for kinks, bends and/or leakage. Check oil lines and high pressure pump in engine "V" for major oil leaks. Inspect for coolant leaks at radiator and heater hoses and check coolant level. Inspect wiring for correct routing and make sure no rubbing or chafing has occurred. Inspect the in-line 42-way, injector driver module (IDM), powertrain control module (PCM) and sensor connectors to make sure they are completely seated and in good condition.
Possible Causes:
- Loose or leaking fuel supply lines could cause fuel system to lose prime.
- Kinked or blocked fuel supply lines will create fuel restriction.
- Massive fuel or oil leaks could contribute to no start conditions.
- Coolant leaks could indicate serious engine problems.
- Electronic connectors may be damaged or not installed properly causing a no start condition. The camshaft position (CMP) sensor and the injection pressure regulator (IPR) are the two most critical electronic sensors/actuators to inspect in no start situations.
Tools Required: Inspection light
2. Check Engine Oil Level
Purpose: To determine if there is enough oil or oil of sufficient quality to operate the injectors.
Recommended Procedure:
Check oil level with dipstick when vehicle is on level ground. If there is no oil or very little oil in the crankcase, the injectors will not operate.
If the oil level on the dipstick is overfull it is possible the engine was incorrectly serviced or fuel is diluting the oil and filling the crankcase. Usually if a substantial amount of fuel is in the oil it will have a fuel odor.
Inspect oil for color. A milky white oil indicates possible coolant contamination and will have an ethylene glycol odor.
Check service records for correct oil type and viscosity for the vehicle operating temperature. Single weight or 15W-40 oil is not recommended for cold ambient temperatures. 10W-30 oil is recommended for cold ambient temperatures. Oil that has had extended drain intervals will have increased viscosity (become thicker) and will make engine cranking more difficult and starting less reliable at temperatures below freezing. Refer to the lube oil chart in the service manual or operator's manual for the correct oil selection for temperature conditions.
The level in the oil reservoir should also be checked. Remove the inspection plug in top of reservoir and check to see if the oil reservoir is full. (A reservoir that drains back after the engine has not been operated for a period of time can cause a hard start and die condition.) Filling the reservoir will allow the system to prime faster facilitating starting.
Possible Causes:
- Oil level low -- oil leak, oil consumption, incorrect servicing.
- Oil level high -- incorrect servicing, fuel dilution from tandem fuel pump, fuel dilution from injector O-rings.
- Oil contamination with coolant -- oil cooler, head gasket, porosity.
- Low reservoir level -- engine built dry (not pressure lubed), prolonged period of not running, leaking check valve in high pressure pump, excessive cranking without starting.
Tools Required: 1/4-inch drive ratchet or breaker bar to remove inspection plug
3. Intake/Exhaust Restriction
Purpose: This is a visual inspection to determine if an air intake or exhaust restriction is contributing to a no start or hard start condition. If the engine does start with a high air intake or exhaust restriction, a considerable amount of black/blue smoke is produced.
Recommended Procedure:
Inspect the air cleaner inlet and ducting to assure that it is not blocked or collapsed. Inspect the air cleaner housing and filter for proper installation. Inspect the filter minder to assure intake restriction is below the red marks.
Inspect the exhaust back pressure device bellcrank during cranking and assure that it is not closing. Inspect the exhaust system for damaged or blocked pipes. When the tang is against the stop, the valve is fully open.
Possible Causes:
- Snow, plastic bags or other foreign material may restrict airflow at the air inlet.
- Misrouted air cleaner ducting.
- On engines recently repaired, rags or cap plugs may have been inadvertently left in an air inlet pipe.
- Exhaust back pressure device may be closing during cranking or stuck closed.
- Tailpipe or muffler may have collapsed or been damaged or the catalytic converter is clogged.
Tools Required: None
4. Sufficient Clean Fuel
Purpose: The purpose of this test is to see if the fuel system is getting sufficient clean fuel to start and run.
Recommended Procedure:
Route a hose from the fuel drain line to a clear container and open the drain. Crank the engine and observe the fuel flowing into the container. Stop cranking the engine when the container is half full.
Observe the WATER IN FUEL lamp while cranking the engine. If the lamp is illuminated, the fuel is probably contaminated with water.
Flow out of the drain should be a steady stream. Insufficient flow could indicate fuel supply or fuel system problems.
Inspect fuel in the container. It should be straw colored, but not cloudy. It also should be free of water and contaminants. Dyed red or blue fuel indicates off-highway fuel.
If engine oil is present in the fuel it may indicate an injector O-ring leak and subsequent loss of rail pressure. If that is suspected, check rail pressure during engine cranking (Hard Start/No Start Diagnostic Procedures Step 9C).
Some sediment and water may be present in the fuel sample if the fuel filter has not been serviced for a prolonged period of time and/or if the sediment and water have not been drained recently. If that is the case a second sample may be required to determine fuel quality.
Possible Causes:
- No fuel in tank.
- If equipped with a fuel line valve, it could be shut off.
- If equipped with dual tanks, the switch valve could be faulty.
- Fuel supply line could be broken or crimped.
- Fuel could be jelled (most likely in cold weather with No. 2 fuel).
- Pickup tube screen in tank could be clogged.
Cloudy fuel indicates that the fuel may not be a suitable grade for cold temperatures, excessive water or contaminants may indicate that the tank and fuel system may need to be flushed and cleaned.
Tools Required: Clear container -- approximately 1-quart
5. Tandem Fuel Pump Pressure
Purpose: To determine if there is sufficient fuel pressure for starting (>20psi from each tank).
Recommended Procedure: Connect Rotunda High Fuel Pressure Adapter 014-00931-3 or equivalent to the Schrader valve mounted in the fuel regulator block. Connect a line for a 160 psi gauge to the adapter. Crank engine at 100 rpm minimum and measure maximum fuel pressure.
Possible Causes:
- A fuel filter could cause high restriction and low fuel pressure because of dirt or fuel jelling in cold ambient temperatures. Change filter and retest. (Note: It may take a couple of crank cycles to purge the air out of the fuel system.)
- Debris in the fuel regulator valve will cause low fuel pressure. Disassemble, inspect and clean.
- A kinked or severely bent fuel supply line or blockage at the pickup tube could cause restriction and therefore low fuel pressure.
- A loose fuel line on the suction side of the fuel system could cause air to be ingested into the system and cause low fuel pressure.
- The fuel pump could have internal damage, e.g., ruptured diaphragm, seized plunger or leaking check valves.
Tools Required:
- 0 to 160 psi fuel pressure gauge
- Rotunda High Fuel Pressure Adapter 014-00931-3 or equivalent line with 1/4-inch NPT fitting
6. Perform KOEO On-Demand Self Test
Purpose: To determine if the PCM has detected any fault conditions that would cause a hard start or no start condition.
Recommended Procedure: Connect the NGS Tester to the data link connector (DLC) under the dash. Turn off accessories. If vehicle is equipped with an auxiliary powertrain control (rpm control), it must be turned off to perform self tests.
- Perform the necessary vehicle preparation and visual inspection. Refer to «Quick Test Operation».
- Select VEHICLE & ENGINE SELECTION menu.
- SELECT NEW VEHICLE, YEAR & MODEL.
- Select DIAGNOSTIC DATA LINK.
- Select PCM-POWERTRAIN CONTROL MODULE.
- Select DIAGNOSTIC TEST MODE.
- Select KOEO ON DEMAND SELF TEST.
- Turn key on.
- Follow operating instructions from the menu.
- Record DTCs and follow appropriate pinpoint test.
- After test, cycle key to off before running other tests or driving vehicle.
If performing repeated self tests, it may be necessary to unplug glow plug relay to keep battery from going dead. Ignore DTC 0380 while glow plug relay is unplugged.
NOTE: If IDM trouble codes are retrieved, use the following special instructions required to clear IDM trouble codes (1995/1996 model year).
- Key on.
- Record IDM trouble codes stored in "KOEO ON DEMAND SELF TEST" and "KOEO INJECTOR ELECTRICAL SELF TEST" modes.
- Access "RETRIEVE/CLEAR CONTINUOUS DTCs" from NGS Tester menu to clear IDM trouble codes from memory.
- Record any codes displayed. (P1111 may be the only code displayed.)
- Push "CLEAR ALL" button on NGS Tester.
- IDM trouble codes are now cleared from memory. Repeat the KOEO On-Demand Self Test and KOEO Injector Electrical Self Test. Any IDM codes that reappear are IDM hard faults. If no IDM codes reappear, then the fault is an intermittent IDM fault.
Possible Causes: The most likely PCM detectable faults that will cause a no start or hard start condition are:
- CMP sensor inactive faults.
- IPR output circuit check fault.
- FDCS, CID and IDM ENABLE circuit faults.
Tools Required: Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
7. Retrieve/Clear Continuous DTCs
Purpose: To determine if the PCM has detected any historical or intermittent fault conditions that would cause a hard start/no start symptom. The condition that caused a continuous DTC may no longer exist.
Recommended Procedure: Connect the NGS Tester to the DLC under the dash. Turn off accessories. If vehicle is equipped with an auxiliary powertrain control (rpm control), it must be turned off to perform self tests.
- Perform the necessary vehicle preparation and visual inspection. Refer to «Quick Test Operation».
- Select VEHICLE & ENGINE SELECTION menu.
- SELECT NEW VEHICLE, YEAR & MODEL.
- Select DIAGNOSTIC DATA LINK.
- Select PCM-POWERTRAIN CONTROL MODULE.
- Select DIAGNOSTIC TEST MODE.
- Select RETRIEVE/CLEAR CONTINUOUS DTCs
- Turn key on.
- Follow operating instructions from the menu.
- Record DTCs and follow appropriate pinpoint test for continuous code diagnostics.
- After test, cycle key to off before running other tests or driving vehicle.
- Continuous DTCs must be cleared after repair is made.
If performing repeated self tests, it may be necessary to unplug glow plug relay to keep battery from going dead. Ignore DTC 0380 while glow plug relay is unplugged.
NOTE: IDM codes must be cleared in this mode even though they only appear in KOEO On-Demand Self Test. If IDM trouble codes are retrieved, use the following special instructions required to clear IDM trouble codes (1995/1996 model year).
- Key on.
- Record IDM trouble codes stored in "KOEO ON DEMAND SELF TEST" and "KOEO INJECTOR ELECTRICAL SELF TEST" modes.
- Access "RETRIEVE/CLEAR CONTINUOUS DTCs" from NGS Tester menu to clear IDM trouble codes from memory.
- Record any codes displayed. (P1111 may be the only code displayed.)
- Push "CLEAR ALL" button on NGS Tester.
- IDM trouble codes are now cleared from memory. Repeat the KOEO On-Demand Self Test and KOEO Injector Electrical Self Test. Any IDM codes that reappear are IDM hard faults. If no IDM codes reappear, then the fault is an intermittent IDM fault.
Tools Required: Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
8. KOEO Injector Electrical Self Test
NOTE: If unable to perform KOEO Injector Electrical Self Test, disconnect IDM connector and check injector high and low side for shorts or opens.
Purpose: To determine if the injector solenoids and valves are operating, by buzzing all injectors together and then buzzing each injector in numerical sequence (1 through 8 ).
Recommended Procedure:
NOTE: If no DTCs are present and the KOEO Injector Electrical Self Test aborts while trying to perform, go to Pinpoint Test AB, Step «AB29».
Connect the NGS Tester to the DLC under the dash. Turn off accessories. If vehicle is equipped with an auxiliary powertrain control (rpm control), it must be turned off to perform self tests.
- Perform the necessary vehicle preparation and visual inspection. Refer to «Quick Test Operation».
- Select VEHICLE & ENGINE SELECTION menu.
- SELECT NEW VEHICLE, YEAR & MODEL.
- Select DIAGNOSTIC DATA LINK.
- Select PCM-POWERTRAIN CONTROL MODULE.
- Select DIAGNOSTIC TEST MODE.
- Select KOEO INJECTOR ELECTRICAL SELF TEST.
- Follow operating instructions from the menu.
- Record DTCs and follow appropriate pinpoint test.
- After test, cycle key to off before running other tests or driving vehicle.
If performing repeated self tests, it may be necessary to unplug glow plug relay to keep battery from going dead. Ignore DTC 0380 while glow plug relay is unplugged.
NOTE: If IDM trouble codes are retrieved, use the following special instructions required to clear IDM trouble codes (1995/1996 model year).
- Key on.
- Record IDM trouble codes stored in "KOEO ON DEMAND SELF TEST" and "KOEO INJECTOR ELECTRICAL SELF TEST" modes.
- Access "RETRIEVE/CLEAR CONTINUOUS DTCs" from NGS Tester menu to clear IDM trouble codes from memory.
- Record any codes displayed. (P1111 may be the only code displayed.)
- Push "CLEAR ALL" button on NGS Tester.
- IDM trouble codes are now cleared from memory. Repeat the KOEO On-Demand Self Test and KOEO Injector Electrical Self Test. Any IDM codes that reappear are IDM hard faults. If no IDM codes reappear, then the fault is an intermittent IDM fault.
Possible Causes:
- Open injector wire.
- Bad injector connector.
- Shorted wire or connector.
- Open solenoid.
- Defective IDM.
Tools Required: Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
9. Check VPWR During Cranking
Purpose: To verify PCM power-up during cranking. Lack of power to PCM can cause a no start condition as well as fault code loss. The NGS Tester requires a minimum system voltage of 9.5 volts to avoid resetting.
Recommended Procedure: Install NGS Tester. Access VPWR PID on NGS Tester and monitor while cranking the engine. Minimum values are:
- VPWR: 7
- RPM: 100
- ICP: 500psi or 3.4mPa
- FUEL PW: 1~6ms
Possible Causes:
- Low battery voltage.
- Charging system problem.
- Power circuit and ground faults to the PCM.
Refer to «Pinpoint Test A» to diagnose a voltage concern.
NOTE: Battery voltage below 9.5 volts can cause the NGS Tester to reset. If the NGS Tester resets during a self test or while PID monitoring, it may be necessary to install a battery charger to maintain the correct voltage.
Tools Required: Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
9b. Check RPM Signal While Cranking
Purpose: To determine if the CMP sensor and circuit are functioning.
Recommended Procedure: Install NGS Tester. Access RPM PID on NGS Tester and monitor rpm reading while cranking the engine. NGS Tester will read rpm if PCM is receiving a CMP signal.
Possible Causes:
- Faulty wire harness connection.
- Poor CMP ground connection.
- Incorrect CMP sensor to target wheel spacing.
- Defective CMP sensor.
Refer to «Pinpoint Test G» for CMP sensor diagnosis.
Tools Required: Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
9c. Monitor ICP While Cranking
Purpose: To determine if the injection control system can supply enough injection control pressure to sustain starting.
Recommended Procedure: Install NGS Tester. Access ICP PID on NGS Tester and monitor ICP reading while cranking the engine.
NOTE: CMP signal is required before injection control pressure is allowed above 400 psi.
If value does not meet the minimum specification, the injectors are not being enabled by the PCM because of insufficient pressure.
Possible Causes:
- Injection control pressure system leak.
- Oil reservoir level low.
- IPR failure.
- Faulty high pressure pump.
Injection Control Pressure Leak Test
Removing the ICP sensor and inspecting the level in the oil rail will determine if oil is being supplied to the rail. Removing the inspection plug in the top of the reservoir will help determine if the reservoir is full. A reservoir that drains back after the engine has not been operated for a long period of time can cause a hard start condition.
Purpose: Isolate the cause of low injection control pressure.
Recommended Procedure:
Right Cylinder Head Check
Remove the high pressure hose from the right cylinder head and cover the fitting on the cylinder head with the appropriate cap from the Fuel/Oil/Turbo Protector Cap Set T94T-9395-AH. Install the plug from the Oil High Pressure Leakage Test Adapter Set D94T-6600-A into the high pressure hose to block it off. Connect the ICP/EBP Adapter Cable D94T-50-A to the ICP sensor. Connect a DVOM between signal return and ICP signal wires on the ICP/EBP Adapter Cable D94T-50-A. Crank the engine and monitor the signal. The DVOM should read 1 to 4 volts.
CAUTION: The engine may start!
If the engine starts or if injection control pressure is now within specification, the injection control pressure leak has been isolated to the right cylinder head. Inspect the fuel to see if oil is in the fuel. If no oil is present in the fuel, remove the valve cover, crank the engine and inspect the injector body and injector bore area for leakage.
CAUTION: Oil is under high pressure!
Left Cylinder Head Check
Remove the cap and plug, then reinstall the high pressure hose to the right cylinder head. Remove the high pressure hose from the left cylinder head and cover the fitting on the cylinder head with the appropriate cap from the Fuel/Oil/Turbo Protector Cap Set T94T-9395-AH. Install the ICP adapter from the Oil High Pressure Leakage Test Adapter Set D94T-6600-A into the high pressure hose. Remove the ICP sensor and install the sensor in the end of the ICP adapter. Connect the ICP/EBP Adapter Cable D94T-50-A to the ICP sensor. Connect a DVOM between the signal return and ICP signal wires of the ICP/EBP Adapter Cable D94T-50-A. Crank the engine and monitor the signal. The DVOM should read 1 to 4 volts.
CAUTION: The engine may start!
If the engine starts or if injection control pressure is now within specification, the injection control pressure leak has been isolated to the left cylinder head.
IPR and High Pressure Pump Test
If injection control pressure is still low after ruling out both cylinder heads as the source of injection control pressure leakage, perform the following steps to isolate the cause. Leave the ICP sensor and ICP adapter connected to the left high pressure hose. Remove the high pressure hose from the right cylinder head and cover the fitting on the cylinder head with the appropriate cap from the Fuel/Oil/Turbo Protector Cap Set T94T-9395-AH. Install the plug from the Oil High Pressure Leakage Test Adapter Set D94T-6600-A into the high pressure hose to block it off. With the high pressure pump effectively deadheaded, crank the engine and monitor the signal. If injection control pressure is not within specification, replace the Injection Pressure Regulator (IPR) with a known good IPR and retest. If a low pressure condition still exists, the problem is most likely with the high pressure pump or the high pressure pump drive gear.
Tools Required:
- Fuel/Oil/Turbo Protector Cap Set T94T-9395-AH
- ICP/EBP Adapter Cable D94T-50-A
- Oil High Pressure Leakage Test Adapter Set D94T-6600-A
- Rotunda Digital Volt-Ohm Multimeter (DVOM) 105-00050 or equivalent
- 1/4-inch drive ratchet or breaker bar to remove inspection plug
9d. Check Fuel Pulse Width (FUEL PW) While Cranking
Purpose: To verify that the Fuel Delivery Command Signal (FDCS) system is functioning correctly.
Recommended Procedure:
Install NGS Tester. Access FUEL PW PID on NGS Tester and monitor while cranking engine. No fuel command signal when ICP, RPM and VPWR signals are correct usually indicates a loss of CMP sync signal. Refer to «Pinpoint Test G» for CMP sensor diagnosis.
A 1 to 6 ms fuel pulse width will be sent by the PCM to the IDM when a sync pulse has been received from the CMP sensor and when sufficient injection control pressure is present. A 0.42 ms fuel pulse width (a no fueling pulse) will be sent by the PCM when a sync pulse has been received from the CMP sensor and if insufficient injection control pressure is present. This 0.42 ms fuel pulse width will not allow injectors to be enabled, but does keep the IDM and PCM synchronized until sufficient injection control pressure is realized.
Possible Causes:
- FDCS circuitry.
- PCM.
- IDM.
Tools Required: Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
10. Glow Plug System Operation
Purpose: To determine if the glow plug system operation is sufficient to permit starting.
Recommended Procedure:
Relay Operation
Install a DVOM on the glow plug feed side of the glow plug relay (large stud with two wires connected). Turn the ignition key to the ON position but do not attempt to start. Note the time in seconds from when the key is turned on and the glow plug relay energizes until the glow plug relay de-energizes. The glow plug relay makes a loud click noise which is easily heard when it energizes and de-energizes. The dome light will dim and the dash voltmeter will dip when the glow plugs are drawing current from the battery. Compare the times measured to the table (time will be affected by engine temperature, battery condition and vehicle altitude). The voltage at the glow plug feed terminal may vary from 9 to 12 volts depending upon battery condition.
If battery voltage is not present, check for B at the power supply terminal (terminal with single large wire). Power for glow plug power supply is supplied from the starter relay through two fusible links at solenoid.
Glow Plug Operation
Disconnect all of the glow plug/injector harness connectors from the valve cover gaskets. With the Rotunda Glow Plug Injector Adapter 014-00935 or equivalent installed, measure glow plug resistance to ground (preferably B-). A resistance measurement of 0.1 to 2 ohms indicates a good glow plug.
Glow Plug Harness Continuity
Measure for continuity from the connector harness to the glow plug feed terminal on the glow plug relay. Resistance should be less than 0.1 to 1 ohm.Incorrect measurements will result if all glow plug/injector connectors to valve cover are not disconnected.
Possible Causes:
Insufficient glow plug ON time will not allow enough heat to accumulate in the combustion chamber to easily facilitate starting. If the glow plug system ON time does not meet any of the specifications in the accompanying chart the problem is most likely a faulty wire harness connection, ground connections or glow plug relay.
If the glow plug resistance to ground is high, the most likely causes are an open under valve cover (UVC) harness or an open glow plug.
Tools Required:
- Rotunda Digital Volt-Ohm Multimeter (DVOM) 105-00050 or equivalent
- Rotunda Glow Plug Injection Adapter 014-00935 or equivalent
- Stop watch or equivalent
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