Part 1 of 4

TEST DESCRIPTION

Fuel Delivery Diagram (Adapters Shown Installed For Testing):

Chart A-7, Fuel System Diagnosis (1 OF 4):

Numbers below refer to circled numbers on the diagnostic chart.

1. Wrap a shop towel around the fuel connections to absorb fuel spilled while installing gauge. Ignition "ON" engine "OFF" fuel pressure should be284 - 325 kPa (41 - 47psi). Pressure is controlled by a spring in the fuel pressure regulator.
2. With the engine idling, manifold vacuum is applied to a diaphragm in the pressure regulator, reducing fuel pressure by 21 - 69 kPa (3 - 10 psi) from previous reading with engine "OFF".
3. Fuel pressure that does not hold steady or gradually "bleeds-off", could be caused by one of the following.

a. In tank fuel pump check valve leaking (integral part of pump)
b. Fuel hose/connection leaking
c. Faulty fuel pressure regulator
d. Leaking injector

4. Leaking injectors can usually be identified by examining spark plus. Plugs that are sooty, fouled, or saturated with fuel indicate cylinders with leaking injectors. If leaking injectors are suspected and cannot be identified this way, use the following procedure.

a. Remove plenum and fuel rail. See COMPONENT SERVICE, REPAIR, AND REPLACEMENT under SERVICE AND REPAIR Leave fuel lines connected, injectors attached to fuel rail, lift fuel rail just enough to observe fuel spray from injectors while injector tips remain in the ports.

WARNING! Fire hazard. Be sure injectors do not spray fuel on engine. Fuel injector retaining clips must be intact and securely in place.

b. Energize fuel pump to pressurize fuel system by applying fused battery power to fuel pump test terminal, or by bridging terminals "C" and "D" of oil pressure switch.
c. Observe injectors, look for fuel leaking from injector nozzle(s).
d. Replace injectors that are leaking.