Prizm L4-108 1.8L DOHC VIN 8 MFI (1998)
Fuel System Diagnosis
System Description
The fuel supply system is a returnless design that has most of the fuel system components located inside of the fuel tank. When the ignition switch is
turned to the START position (engine cranking), the circuit opening relay will be energized in order to allow the fuel pump to operate and pressurize the
system. The fuel pump will continue to operate if the powertrain control module (PCM) receives an ignition signal when the engine is started. The fuel
pump operates as long as the circuit opening relay is energized by the PCM. When the circuit opening relay is de-energized, the fuel pump will stop
operating. The fuel pump delivers fuel to the fuel rail at high pressure. The fuel pressure regulator, located in the fuel tank, is responsible for keeping the
fuel pressure at 301-347 kPa (44-50 psi).
Diagnostic Aids
Check that the fuel pressure regulator has not come loose or is miss positioned. This may cause a low fuel pressure condition.
Check for leakage around all fuel hose/pipe connections. A plugged fuel injector could be the cause of a hard/no-start condition or loss of power. Erratic
fuel pressure may be caused by a fault in the fuel pump electrical circuit. Inspect the wiring harness and components for any of the following conditions:
^
Backed out terminals.
^
Improper mating of terminals.
^
Broken electrical connectors locks.
^
Improperly formed or damaged terminals
^
Faulty terminal to wire connections.
^
Physical damage to the wiring harness.
^
A broken wire inside the insulation.
^
Corrosion of electrical connections, splices, or terminals.
Test Description
The numbers below refer to the step numbers in the Diagnostic Table.
1. The OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This
creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
