The fuel injectors are mounted on the left side of the cylinder head on 1997-98 models, on the top, center of the head on 1999-00 models, and are connected to the fuel pump by the high pressure fuel lines.
The injectors consist of the nozzle holder, O-ring, water seal, shims, spring, needle valve and nozzle. Fuel enters the injector through the top of the injector (fuel inlet) and is routed to the needle valve bore. The injector fires when fuel pressure rises to an amount sufficient to overcome the needle valve spring tension. The pressure needed to overcome the needle valve spring tension is about 4,000 psi (28,000 kPa). This pressure is commonly known as the "pop" pressure.
As the needle valve opens, fuel flows rapidly through the spray holes in the nozzle tip into the combustion chamber. After this injection, the fuel pressure drops and the needle valve is closed preventing further fuel flow, and conversely, exhaust flow into the injector.
Removal & Installation
- Before servicing the vehicle, refer to the Precautions Section.
Remove or disconnect the following:
Negative battery cables
- Use a new copper washer and coat the backing nut threads with anti-seize compound.
Install or connect the following:
Fuel injector. Tighten the mounting nut to 44 ft. lbs. (60 Nm).
- Bleed the fuel system.
- Start the engine and check for leaks.
- Disconnect the negative battery cable(s). Remove the throttle linkage and bracket if necessary.
- To access the injectors at cylinders #1 and #2, remove the intake manifold heater assembly. To access the injector at cylinder #5, remove the engine-lifting bracket.
- Clean the area around the injector.
- Disconnect the high-pressure fuel supply line to the injector.
- Remove the valve cover.
- Thread special tool 8324 onto the end of the injector tube and pull injector tube from cylinder head. Remove and discard the old O-ring.
- Remove the fuel injector hold-down clamp bolt at front end of clamp. Do NOT loosen or remove special bolt at rear end of clamp. Remove injector by sliding it out.
- Thread the rod from special tool 8318 into the top of the fuel injector. Remove injector from cylinder head.
- Reverse the removal procedure.
- Use a new copper sealing washer and a new O-ring. Copper washer thickness must be 0.060 in. (1.5mm).
- Oil all parts before installation.
- Position the inlet hole towards connector tube.
- Tighten the opposite clamp bolt to 89 inch lbs. (10 Nm).
A leaking fuel injector can cause fuel knock, poor performance, black smoke, poor fuel economy and rough engine idle. If the needle valve does NOT operate properly, the engine may misfire and produce low power.
A leak in the injection pump-to-injector high-pressure fuel line can cause many of the same symptoms as a malfunctioning injector. First check the lines before the injectors.
- To check the injectors, start the engine and loosen the high-pressure line nut one-at-a-time at each injector. Listen for a decrease in engine speed.
- If the engine speed drops, the injector is operating normally. If the engine speed remains the same, the injector is malfunctioning. After testing each injector, tighten the line nuts to 22 ft. lbs. (30 Nm) on 1997-98 Models, 30 ft. lbs. (40 Nm) on later units.
- If an injector is found to be malfunctioning, remove it and test it on a standard bench-mount injector tester. Follow the manufacturer's instructions for bench testing the injector.
- If the opening (pop) pressure is below specifications, replace the injector. The pop pressure is 3,822 psi (26,252 kPa) for 1997-98 Models, 4,500 psi (31,026 kPa) for 1999-2000 Models.