REMOVAL & INSTALLATION
See Figures 1 through 5
- Relieve the fuel system pressure.
- On all except early model 7.5L engines, remove the upper intake manifold assembly.
- Remove the fuel rail.
- Disengage the electrical connections from the injectors.
See Figure 2
- Pull upward on the injector body while gently rocking it from side-to-side.
- Inspect the O-rings on the injector for any sign of leakage or damage. Replace any suspected O-rings.
- Inspect the plastic cap at the top of each injector and replace it if any sign of deterioration is noticed.
- Lubricate the O-rings with clean engine oil ONLY!
- Install the injectors in the manifold by pushing them in with a gentle rocking motion.
- Connect the electrical wiring.
- Install the fuel rail.
- If removed, install the upper intake manifold.
Fuel Injector Pressure Test
See Figures 6, 7 and 8
- Connect pressure gauge T80L-9974-A, or equivalent, to the fuel pressure test fitting. Detach the coil connector from the coil. Disconnect the electrical lead from one injector and pressurize the fuel system. Disable the fuel pump by disconnecting the inertia switch or the fuel pump relay and observe the pressure gauge reading.
- Crank the engine for 2 seconds. Turn the ignition OFF and wait 5 seconds, then observe the pressure drop. If the pressure drop is 2-16 psi (14-110 kPa), the injector is operating properly. Reconnect the injector, activate the fuel pump, then repeat the procedure for the other injectors.
- If the pressure drop is less than 2 psi (14 kPa) or more than 16 psi (110 kPa), switch the electrical connectors on injectors and repeat the test. If the pressure drop is still incorrect, replace the disconnected injector with one of the same color code, then reconnect both injectors properly and repeat the test.
- Disconnect and plug the vacuum hose at EGR valve. It may be necessary to disconnect the idle air control valve and use the throttle body stop screw to set the engine speed. Start and run the engine at 1,800 rpm (2,000 rpm on 1984 and later models). Disconnect the left injector electrical connector. Note the rpm after the engine stabilizes (around 1,200 rpm). Reconnect the injector and allow the engine to return to high idle.
- Perform the same procedure for the right injector. Note the difference between the rpm readings of the left and right injectors. If the difference is 100 rpm or less, check the oxygen sensor. If the difference is more than 100 rpm, replace both injectors.