Ford / Lincoln /Mercury
4.6L Intake Manifold Repair


  1. Engine fails to crank:
    • Check that the battery has been re-connected.
    • If you removed the fuel pump relay or tripped the fuel pump cut-off switch to de-pressurize the fuel system make sure these are re-installed and/or reset (see CAUTION section following step 17).
    • Check that the throttle position sensor (TPS) and idle air control (IAC) are connected properly (step 50).
  2. Engine cranks but runs rough:
    • Unless the engine is making some God-awful noises, let the engine run for 1-2 minutes to see if it smoothes out. Disconnecting the battery causes the computer to revert to it's default settings (mixture, spark advance, etc.). It may take a few seconds of engine runtime for the computer to get things lined out. Also, there may have been some air in the fuel lines which needs to work it's way out. If after 2-3 minutes the engine is still running rough review the steps below.
    • Check to make sure all the spark plug wires are connected and in the correct firing order.
    • Check the connectors to each of the fuel injectors. Make sure they're seated and that they are connected to the correct injector.
    • Check that the throttle position sensor (TPS) and idle air control (IAC) are connected properly (step 49 above).
    • Make sure that the Mass Air Flow meter (MAF) connector is properly connected. The MAF is mounted to the air cleaner housing (usually near the fender). This connection should not have disconnected in the service steps above but may have been disconnected by mistake.
  3. Fuel is leaking from around the top and/or bottom of the injectors:
    • Make sure the injectors are seated properly in the intake manifold.
    • Make sure the fuel injection rail assembly is properly seated on all 8 injectors and that it is secured by the hold-down studs which screw into the intake manifold.
  4. Coolant is leaking:
    • Check that you tightened the upper radiator hose at the radiator and thermostat housing.
    • Check to make sure your tightened the thermostat housing properly using the spacers and new O-ring provided in the intake manifold kit.
    • Make sure you tightened the hose clamps on the heater hose (rear of intake manifold).


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