CAUTION: The engine may start!1996 PCED OBDI | SECTION 18: Diesel Diagnosis — 7.3L DI Engine |
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.
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.
Inspection light
To determine if there is enough oil or oil of sufficient quality to operate the injectors.
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.
1/4-inch drive ratchet or breaker bar to remove inspection plug
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.
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.
None
The purpose of this test is to see if the fuel system is getting sufficient clean fuel to start and run.
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.
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.
Clear container — approximately 1-quart
To determine if there is sufficient fuel pressure for starting.
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.
To determine if the PCM has detected any fault conditions that would cause a hard start or no start condition.
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.
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).
The most likely PCM detectable faults that will cause a no start or hard start condition are:
Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
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.
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.
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).
Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
Note: If unable to perform KOEO Injector Electrical Self Test, disconnect IDM connector and check injector high and low side for shorts or opens.
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).
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.
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).
Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
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.
Install NGS Tester. Access VPWR PID on NGS Tester and monitor while cranking the engine.
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.
Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
To determine if the CMP sensor and circuit are functioning.
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.
Refer to Pinpoint Test G for CMP sensor diagnosis.
Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
To determine if the injection control system can supply enough injection control pressure to sustain starting.
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.
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.
Isolate the cause of low injection control pressure.
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!
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.
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.
To verify that the Fuel Delivery Command Signal (FDCS) system is functioning correctly.
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.
Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent
To determine if the glow plug system operation is sufficient to permit starting.
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.
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.
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.
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.