How to Test a BAD Fuel Injector (1998 4.6L Ford Crown Victoria -4.6L Mercury Grand Marquis)

Like most of the components on your car, the fuel injectors can be tested to find out if they are bad or not. In other words, you don't have to run out to your local auto parts store to buy one not really knowing if it has failed or not. In this tutorial I'm gonna' explain the multimeter resistance test you need to know to test them all.

Also, finding the bad or clogged fuel injector is not that hard. In the next page I'm gonna' show you a very simple troubleshooting method to find the clogged (or failed) fuel injector.

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 Crown Victorias (Mercury Grand Marquis) not covered by this tutorial:

  1. How to Test the Fuel Injectors (1992-1997 4.6L Crown Victoria).
  2. How to Test the Fuel Injectors (1999-2000 4.6L Crown Victoria).

Symptoms of Bad Fuel Injector

Because every cylinder on your 4.6L v8 engine needs fuel, air, and spark to produce power, when the fuel injector stops working (or doesn't spray enough fuel because it has become clogged) the engine in your car is going to suffer a misfire. Here are 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 (1998 4.6L Ford Crown Victoria -4.6L Mercury Grand Marquis)

I'm gonna' suggest that you test all 8 fuel injectors on your 1998 4.6L Crown Victoria (1998 4.6L Grand Marquis). Yep, even if you have a specific misfire trouble code, I recommend that you test them all.

The fuel injector resistance specification is 11 - 18 Ohms. Now of course you're going to need a multimeter to be able to test the resistance value of the fuel injectors, if you don't have one and are looking to buy a multimeter, check out my recommendations here: Buying a Digital Multimeter for Automotive Diagnostic Testing (at: easyautodiagnostics.com).

Alright, lets get testing:

  1. 1

    Disconnect the fuel injectors from their engine wiring harness connectors.

    NOTE: The illustration above will help you to identify the number of each cylinder so that you'll know which fuel injector belongs to what cylinder.

  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: Your test results indicate that all 8 fuel injector resistances are within specification (11 to 18 Ohms). This tells you that the internal coil winding of each fuel injector is OK.

But, there's a chance that the misfiring cylinder has a clogged fuel injector. So my suggestion is to check out the troubleshooting guidelines in this section: How to Find the BAD or Clogged Fuel Injector.

CASE 2: Your test results indicate that one or several fuel injectors ARE NOT within specification. If the fuel injector's resistance value is not within the 11 - 18 ohms specification. Then you can conclude that that fuel injector is fried and needs to be replaced.