How To Test The Fuel Injectors (1992-1997 4.6L Crown Victoria, Grand Marquis)

PART 2: Checking The Fuel Injector Spray Pattern

Checking the fuel injector to see if it can actually spray fuel isn't difficult, but it's a process that requires a special tool.

Here's what the tool kit includes:

• A 12 Volt power module that triggers the fuel injector in pulses, just like the fuel injection computer does.
• An adapter that connects the fuel injector to a spray can of brake cleaner.

The process of checking the fuel injector's spray pattern involves removing the suspected clogged fuel injector, attaching it to the spray can of brake cleaner, and then using the power module to activate the injector to see if spray pattern.

If the fuel fuel injector is OK, it should spray the brake cleaner in a fine mist. If the injector is clogged or has any type of internal issue, it'll either squirt the cleaner or fail to spray at all.

You can purchase the took kit here:

• QX Fuel Injector Tester & Adapter for Diagnosis and Cleaning of Injectors DIY Cleaning Tool Kit (at: amazon.com).
• EM276SET Fuel Injector Tester & Adapter DIY Cleaning Tool Kit Set (at: amazon.com).

IMPORTANT: Before installing the same or new fuel injector back on the fuel injector rail, take a look at: Important Tips For Installing A Fuel Injector.

CAUTION: Use safety glasses when performing the fuel injector cleaning procedure.

Alright, these are the test steps:

1. 1

   Remove the fuel injector.

2. 2

   Connect the fuel injector to the plastic adapter.
   
   NOTE: I've found that securing the fuel injector to the adapter with a thick rubber band helps to make the whole process easier and less messier.

3. 3

   Connect the fuel injector to the tool's power module.
   
   NOTE: Follow the tool's safety and recommended set-up instructions.

4. 4

   Connect the cleaning kit's power module to your pickup's battery.

5. 5

   Connect the fuel injector/adapter to a spray can of brake cleaner and press them onto the spray can.

6. 6

   Activate the power module.

7. 7

   The fuel injector should spray fuel in a fine mist and in a conical shape.

Let's interpret your test result:

CASE 1: The fuel injector did not spray at all. This tells you that the fuel injector is bad and needs to be replaced.

CASE 2: The fuel injector sprayed the brake cleaner in a fine mist and in a conical pattern. This tells you that the fuel injector is OK.

CASE 3: The fuel injector sprayed the brake cleaner in a squirt or a stream (not in a fine mist). This tells you that the fuel injector is dirty/clogged.

Continue cleaning the fuel injector until it starts to spray in a fine mist. If the cleaning it doesn't restore the injector's spray pattern to that of a fine mist, you'll need to replace it.

Important Tips For Installing A Fuel Injector

When you're done with your tests and installing either the same or a new fuel injector back on the fuel injector rail, it's important to follow these tips:

• Use New Fuel Injector O-Rings: Always replace the O-rings when installing a fuel injector, whether it's new or the same old one. New injectors usually come with new O-rings, but if you're reinstalling the same injector, you'll need to buy them separately. I really want to emphasize that new O-rings are super important for ensuring a good seal and avoiding gasoline and vacuum leaks.
• Lubricate The O-Rings: It's important to coat the O-rings with a thin layer of clean engine oil (5W-30 or lighter). Don't use any silicone-based grease or other types of lubricants (like wheel bearing grease).
  
  Lubricating the O-rings with light engine oil helps avoid damaging them when inserting the fuel injector into both the injector rail and the intake manifold port. If installed without lubrication, they'll end up getting damaged and you'll have gasoline or vacuum leaks when you crank and start the engine.
• Replace Broken Connectors: Ford fuel injector connectors are known for their locking tabs breaking when disconnected from the fuel injector. If the fuel injector connector is damaged, you've go to replace it now that you've got the plenum removed and have easy access to it.
• Avoid Using Butt Connectors: If you do need to replace a fuel injector connector, don't use butt connectors to join the new connector's wires to the engine wiring harness. Instead, solder the wires for a permanent repair. Butt connectors will lose their grip on the wires over time, leading to false contact issues.

Remember, the goal is to prevent gasoline leaks and avoid the risk of fire. Take your time to ensure everything is properly seated and secure.

More 4.6L Crown Vic And Grand Marquis Tutorials

There are quite a few 4.6L Ford Crown Victoria (Mercury Grand Marquis) 'how to' tutorials and wiring diagrams in this index:

• 4.6L Crown Victoria And Grand Marquis Index of Articles.

E-Series Vans: You can find all of the available tutorials and wiring diagrams for the 4.6L and 5.4L V8 E-Series vans in this index:

• 4.6L, 5.4L Ford E150, E250, And E350 Index of Articles.

F-Series Pickups: You can find all of the available tutorials and wiring diagrams for the 4.6L And 5.4L V8 F-Series pickups in this index:

• 4.6L, 5.4L Ford F150, F250, And F350 Index of Articles (at: easyautodiagnostics.com.com).