drain water from filter. change filter. prime system.
If it doesn't fix it, check glow plugs to be sure they are preheating combustion chamber.
Fuel Supply System
The fuel system consists of the following three major subsystems:
- Fuel supply system
- Injection control pressure system
- Fuel injector assembly
The fuel transfer pump is a camshaft-driven, two-stage diaphragm/piston pump mounted in the engine "V".
Fuel is drawn from the fuel tank through the primary filter by the diaphragm section of the transfer pump. Pressurized fuel (approximately 28 kPa [ 4 psi]) is supplied to the secondary filter and returned to the second stage of the transfer pump. The piston-actuated second stage of the transfer pump supplies 276-345 kPa (40-50 psi) of fuel to the rear of each cylinder head where it flows to a fuel rail machined in each head.
Drillings in the cylinder head route the fuel to the plunger area of the fuel injector which can pressurize the fuel to 124,110 kPa (18,000 psi) for delivery to the combustion chamber via a conventional nozzle/valve tip arrangement.
Return fuel is plumbed from fittings at the front of each cylinder head to a junction block which contains a piston/spring type regulator valve that maintains pressure to approximately 414 kPa (60 psi). A de-aeration bleed orifice between the fuel filter and the regulator block vents air trapped in the fuel filter. Most of the fuel from the regulator is recirculated to the inlet of the piston (high pressure) stage of the transfer pump. Fuel return to the tank is limited to 30-38 liters (8-10 gallons) an hour through the use of a 0.0008mm (.020-inch) orifice. This prevents the fuel from overheating in the tank.
Injector Driver Module
The injector driver module (IDM) is used in conjunction with the PCM to sequentially control power to the fuel injectors on the 7.3L DI turbo diesel engine. The PCM processor generates two digital control signals for the IDM: fuel delivery control signal (FDCS) and cylinder identification (CID). The FDCS signal is used by the IDM to control injection timing and injection duration. The CID provides synchronization to the engine's first and fifth injector (firing order). The IDM verifies that FDCS and CID occur at valid timing intervals. The IDM outputs an electronic feedback (EF) signal, to the PCM, which is a delayed mimic of the FDCS for verification. Selected diagnostic information is also passed to the PCM via the EF signal in run mode.
The IDM is a high-energy power supply which acts as an energy distributor to provide regulated injector energy and control to the unit fuel injectors, based on FDCS and CID commands from the PCM. All IDM components are solid state; there are no user serviceable parts or adjustments. The IDM internal power supply uses a DC-to-DC converter to boost the supply voltage (VBATT) up to 115V DC. This supply is required to overcome the initial impedance of the injectors, ensuring rapid turn on. There are two high side drivers, one for each bank (left and right cylinder bank), and eight low side drivers, one for each injector. One high and one low side must be turned on to energize an injector. Once synchronized with the PCM, the IDM will select the proper low side driver (enable) and control the corresponding high side driver to regulate the current to an injector.
Continuous and on-demand system diagnostic information is provided between the PCM processor and the IDM via the EF signal. During normal operation, the IDM can indicate to the PCM that an injector low side short to ground has been detected, or that the IDM has lost synchronization.
The IDM constantly performs self-diagnostics and also monitors the injector circuits for electrical faults. Any fault codes set are transmitted via the EF signal to the PCM during Key On/Engine Off On-Demand Self Test. If the PCM is unable to obtain diagnostic information from the IDM, DTC 1668 is set.
Glow Plug Control
Glow plugs are used to warm the cylinders to improve cold-engine starting. The PCM uses the engine oil temperature (EOT) sensor and barometric pressure (BARO) sensor to determine how long the glow plugs will be on. The PCM energizes the glow plugs longer if the engine is very cold or if the barometric pressure is low at high altitudes.
The PCM controls the relay that supplies power to the glow plugs with the glow plug control (GPC) signal. When the GPC signal is grounded by the PCM the relay closes, turning the glow plugs on.
The glow plugs are controlled by the following sequence:
- PCM energizes the glow plugs.
- The PCM energizes the glow plugs immediately after the ignition is placed in the ON position.
- The PCM then determines how long glow plugs will be on based on EOT sensor and the BARO sensor. The required time to warm up the cylinder decreases the engine oil temperature and barometric pressure increases at low altitudes.
Glow Plug Lamp Control
The glow plug lamp (GPL) signal controls the WAIT TO START light located on the instrument panel. This light is used to indicate when to start the engine. The cylinders are being warmed by the glow plugs during and after this light is lit. The PCM energizes the glow plug lamp longer if the engine is very cold or if the barometric pressure is low.
When the GPL signal is brought low, the "Wait to Start" lamp is turned on.
The glow plug lamp is controlled by the following sequence:
- PCM lights the WAIT TO START light after a key on reset occurs.
The PCM determines the glow plug lamp activation time based on engine oil temperature, barometric pressure and battery voltage.
- PCM turns off the WAIT TO START light.
The glow plug lamp is turned off when the timer counts to the number of seconds specified by the PCM. The glow plugs will normally remain on longer than the "Wait to Start" lamp.