Prizm L4-1600cc 1.6L DOHC VIN 5 (1989)
Fuel Fluid Diagram
CIRCUIT DESCRIPTION:
The fuel pump delivers fuel to the fuel rail and injectors, where the system pressure is controlled from 265 to 304 kPa (38 to 44 psi) by the pressure
regulator. Excess fuel is returned to the fuel tank. When the engine is stopped, the pump can be energized by applying battery voltage to the test terminal
located in the engine compartment. With engine turned "OFF," fuel pressure should remain above 147 kPa (21 psi) for five minutes.
TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.
1.
Use pressure gauge J 34730-1. Wrap a shop towel around the fuel pressure tap to absorb any small amount of fuel leakage that may occur when
installing the gauge. (The pressure will not leak down after the fuel pump is stopped on a correctly functioning system).
2.
While the engine is idling, manifold pressure (vacuum) is low. When applied to the fuel regulator diaphragm, the pressure will result in a lower
fuel pressure of about 207-241 kPa (30-35 psi).
3.
The application of vacuum to the pressure regulator should result in a fuel pressure drop.
4.
Pressure leak-down may be caused by one of the following:
^
In-tank fuel pump check valve not holding.
^
Pump coupling hose leaking.
^
Fuel pressure regulator valve leaking.
^
Injector sticking open.
DIAGNOSTIC AIDS:
Improper fuel system pressure may contribute to one or all of the following symptoms:
^
Cranks but won't run.
^
Cutting out (May feel like ignition problem).
^
Hesitation, loss of power or poor fuel economy, See: Computers and Control Systems/Testing and Inspection
The following procedure outlines the installation and removal of the Fuel Pressure Gage Assembly. Make certain to observe all "Cautions" while
performing this procedure.
REQUIRED TOOLS:
Port Fuel Pressure Gauge ....................................................................................................................................................................................... J 34730-1
Fuel Rail Adaptor ...................................................................................................................................................................................................... J 38347
