How to Test a BAD Fuel Injector (1999-2000 4.6L Ford Crown Victoria)

Have a multimeter? Then you can test the fuel injectors on your 1999-2000 4.6L Crown Victoria to see if any have failed.

This multimeter resistance test isn't hard to perform since the fuel injectors are very accessible. You also don't need any expensive diagnostic equipment to test them (like a scan tool).

In this tutorial I'll show you how in a step by step manner.

Contents of this article at a quick glance:

  1. Symptoms of Bad Fuel Injector.
  2. Checking the Injector's Internal Resistance.
  3. How to Find the BAD or Clogged Fuel Injector.
  4. Where to Buy the Fuel Injector and Save.

NOTE: The following tutorials may be of help to test the fuel injectors on the 1992-1998 Crown Victorias (Mercury Grand Marquis):

  1. How to Test the Fuel Injectors (1992-1997 4.6L Crown Victoria).
  2. How to Test the Fuel Injectors (1998 4.6L Crown Victoria).

Symptoms of Bad Fuel Injector

Whether a fuel injector shorts out internally or becomes clogged, the end result is a misfire. You'll be able to feel this misfire when the engine is idling or under load (like when you're accelerating the vehicle from a traffic light). Here a few other symptoms you'll see:

  1. Rough idle.
  2. Lack of power.
  3. Hesitation when you accelerate your car down the road.
  4. Misfire trouble codes:
    1. P0300: Random Cylinder Misfire.
    2. P0301: Cylinder #1 Misfire.
    3. P0302: Cylinder #2 Misfire.
    4. P0303: Cylinder #3 Misfire.
    5. P0304: Cylinder #4 Misfire.
    6. P0305: Cylinder #5 Misfire.
    7. P0306: Cylinder #6 Misfire.
    8. P0307: Cylinder #7 Misfire.
    9. P0308: Cylinder #8 Misfire.

Checking the Injector's Internal Resistance

How to Test a BAD Fuel Injector (1999-2000 4.6L Ford Crown Victoria)

OK, this is what you signed up for! We're gonna' check the resistance of each fuel injector with a multimeter in Ohms mode.

Before you start, let me tell you that Ford made a change to its fuel injector connector. The new style of fuel injector connector locking tab is prone to breaking by simply depressing it to unlock the connector from the injector (when trying to disconnect it from the injector).

Broken fuel injector connector locking tabs are one of the most common fuel injector problems on these 1999-2000 4.6L Ford Crown Victorias. Once its locking tab is broken, the connector will make a false connection. This false connection will provoke a misfire.

So, before you start disconnecting the fuel injectors on your Crown Victoria, gently tug on the connector (without depressing its locking tab) to see if it disconnects from the injector.

If any one of the fuel injector connectors becomes disconnected, then you have found a broken fuel injector connector that's causing a misfire. This fuel injector connector has to be replaced.

Sadly, there is an 80% probability that by just unplugging each fuel injector, to test it, the locking tab will break. In my opinion, this is a built-in defect to get you to buy a new connector and keep the economy going.

If you do need to buy the fuel injector connector, I've included a link to where you can find them here: Where to Buy the Fuel Injector and Save.

OK, these are the test steps:

  1. 1

    Disconnect the fuel injectors from their engine wiring harness connectors.

    NOTE: Use the illustration of the engine block (in the image above) to identify the cylinder # the injector belongs to.

  2. 2

    Set your multimeter to Ohms (Ω) mode and:

    Measure the resistance of the fuel injector across its two male spade terminals with the multimeter test leads (see the illustration above).

  3. 3

    Write down the resistance value that your multimeter records for the specific fuel injector you're testing. The illustration above will help you identify the cylinder # the fuel injector belongs to.

  4. 4

    Repeat steps 1 through 3 on the remaining fuel injectors.

    NOTE: The fuel injector resistance specification is: 11 to 18 Ohms.

Let's find out what your specific multimeter test results mean:

CASE 1: All 8 fuel injectors are within the specified resistance parameters (11 to 18 Ohms). This tells you that the fuel injectors are OK. To be a bit more specific, they're not shorted or open internally.

Now, if the cylinder is misfiring, there's a good chance that the fuel injector might be clogged. I suggest taking a look at the following section: How to Find the BAD or Clogged Fuel Injector.

CASE 2: One or several fuel injectors ARE NOT within the specified resistance parameters (11 to 18 Ohms). The fuel injector, whose resistance did not fall within the specified value, is bad and needs to be replaced.