Toronado V6-231 3.8L (1986)
Fuel System Pressure Test for Chart A-7
CHART A-7 - FUEL SYSTEM PRESSURE TEST
Circuit Description:
The fuel pump will deliver fuel to the fuel rail and injectors, then to the pressure regulator, where the system pressure is controlled to 234 to 276 kPa (34
to 40 psi). Excess fuel pressure is bypassed back to the fuel tank. When the engine is stopped, the pump can be turned "ON" by applying battery voltage
to the test terminal located in the engine compartment.
Improper fuel system pressure may contribute to one or all of the following symptoms:
^
Cranks but won't run.
^
Code E044 or E045.
^
Cuts out, may feel like ignition problem.
^
Hesitation, Loss of power or Poor fuel economy.
Test Description:
The following numbered steps correspond with the step numbers on diagnostic chart.
1.
Use pressure gage 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 gage. With ignition "ON" pump pressure should be 234-276 kPa (34-40 psi). This pressure is controlled by spring pressure and
throttle body vacuum within the pressure regulator assembly. Pressure should not leak down after the fuel pump is shut "OFF".
2.
When the engine is idling, the throttle body vacuum is high and is applied to the fuel regulator diaphragm. This will offset the spring and result in a
lower fuel pressure, 172-240 kPa (25-3 5 psi).
3.
The application of 12-14 inches of vacuum to the pressure regulator should result in a fuel pressure of 165-240 kPa (25-35 psi)
4.
Pressure that leaks 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.
