How To Test The Fuel Pump (1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 4.0L Ford Explorer, Aerostar, And Mercury Mountaineer)

If the fuel pump fails, your Ford 4.0L V6 equipped SUV or mini-van is non gonna' start and run.

Thankfully, Ford has made it super piece of cake to examination the fuel pump on your 4.0L Ford Explorer (four.0L Mercury Backwoodsman and four.0L Ford Aerostar) and in this tutorial I'll show you how to do it.

Note: Y'all tin discover the iv.0L Ford Ranger (Mazda B4000) fuel pump exam tutorial here:

  • How To Test The Fuel Pump (1991-2011 Ford 4.0L Ranger And Mazda B4000) (at: easyautodiagnostics.com).

IMPORTANT: Gasoline is extremely combustible! Take all necessary safety precautions, be warning, be careful. Starting fluid and gasoline can ignite very easily.

En Español You can find this tutorial in Castilian here: Cómo Probar La Bomba De Flammable (Ford 4.0L) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

  • iv.0L V6 Ford Aerostar: 1991, 1992, 1993, 1994, 1995, 1996, 1997.
  • four.0L V6 Ford Explorer: 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010.
  • 4.0L V6 Mercury Backwoodsman: 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010.

Symptoms Of A Bad Fuel Pump

A bad fuel pump will make your four.0L Ford Explorer (Aerostar, or Mercury Mountaineer) crank but not start. Here are some more than specific symptoms:

  • The ignition coil pack is creating and delivering spark to all half-dozen spark plugs. So you lot know that the ignition system is not at fault.
  • Yous've sprayed starting fluid (or carburetor spray) into the throttle body and your vehicle started, even if only momentarily.

Although the above list is a not a very complete list of symptoms, the theme that runs thru' them, and any other related symptom, is that the engine volition crank and crank, but not start.

Where To Buy A Fuel Pressure Judge

Owning a fuel pressure gauge is now condign a must. All vehicles now use an electrical fuel pump to evangelize fuel (under high pressure) to the fuel injectors and the best way to diagnose this fuel pump is with a fuel pressure level gauge.

Thankfully, in all of the Ford 4.0L V6 equipped vehicles, Ford was kind enough to put a Schrader valve on the fuel injector rail where yous can tap into the fuel arrangement and bank check its functioning.

A fuel pressure gauge tin can cost yous every bit fiddling as $forty (United states) or as much equally $200 (U.s.). The price difference depends on what type of fuel force per unit area gauge set yous buy, this means either buying a non-professional technician grade tool or a professional person technician course as well. Whichever one you purchase, it'south an investment that will pay for itself many times over.

Your local parts house volition have a fuel pressure gauge set to sell y'all, although you'll pay more than for it and it won't be a professional form tool (if that'due south what you're looking for).

TEST 1: Fuel Pressure Examination With Guess

Using A Fuel Pressure Test Gauge To Check For A Lack Of Fuel Condition. How To Test The Fuel Pump (1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 4.0L Ford Explorer, Aerostar, And Mercury Mountaineer)

As mentioned at the first of this tutorial, testing the fuel pump with a fuel pressure judge is very like shooting fish in a barrel.

What makes it piece of cake is that you'll discover a Schrader valve on the fuel injector rail that you can connect a fuel pressure approximate to (come across: Location Of The Fuel Pressure Schrader Valve Test Port).

Using a fuel pressure gauge is one of the most accurate ways to ensure that plenty fuel reaches the fuel injectors.

If you don't own i, y'all can run down to your local AutoZone or O'Reilly Automobile Parts shop and borrow 1 from them (for a small cash deposit, which you'll get back when y'all return the tool).

If you lot're interested in ownership one, take a wait at my recommendations hither: Where To Buy A Fuel Pressure Guess.

You lot can find the fuel pressure specifications here:

  • Fuel Pressure Specifications (1991-1997 iv.0L Ford Aerostar).
  • Fuel Pressure level Specifications (1991-2010 4.0L Ford Explorer, Mercury Backwoodsman).

Notation: If yous haven't already checked the fuel pump inertia switch, do and so before you get-go this test. For more info on the fuel pump inertia switch, have a await at this section: Checking The Fuel Pump Inertia Switch.

OK, let's go started with this test:

  1. 1

    Place a shop towel nether the Schrader valve. The store towel's chore is to absorb any fuel that may leak when doing pace 2.

  2. 2

    Install the Ford Schrader valve adapter on the Schrader valve.

  3. 3

    Connect the fuel pressure approximate to the Schrader valve adapter.

  4. 4

    When ready, inquire your helper to cycle the cardinal ON and OFF but don't crank the engine while checking for fuel leaks.

    If no fuel leaks, go to adjacent footstep.

    If fuel is leaking, resolve the leak before continuing to the next step .

  5. 5

    Have your helper to crank the engine while you observe the fuel pressure tester'south gauge.

  6. 6

    Your fuel pressure guess will register one of the ii following results:

    i.) The fuel pressure gauge volition register the indicated fuel force per unit area specification

    ii.) The fuel pressure level gauge volition Not register the indicated fuel pressure level specification.

OK, at present that the testing part is done, let's take a expect at what your results mean:

Instance 1: The fuel pressure estimate registered 0 PSI. This confirms that the cause of your engine's no-start trouble is caused past a lack of fuel.

Now, I ordinarily take 2 more than precautions, before condemning the fuel pump as bad and this is to check:

  1. That the fuel pump inertia switch isn't activated and cutting ability to the fuel pump. For more info on this have a look at the next section: Checking The Fuel Pump Inertia Switch.
  2. If the fuel pump inertia switch is OK, then I still brand sure that the fuel pump is getting 12 Volts equally the engine is cranking. This is just to make sure that the fuel pump relay and fuse are OK and doing their job.

To check that the fuel pump is getting power (afterwards the inertia switch has been checked) you'll need to attach a multimeter in Volts DC fashion to the wire that supplies this voltage to the fuel pump and while a helper cranks the engine, verify that the fuel pump is getting this power. If the 12 Volts are being supplied to the fuel pump, you have at present 100% verified that the fuel pump is fried and needs to be replaced.

Case 2: The fuel pressure gauge registered the correct fuel pressure specification. This fuel pressure estimate result lets you lot know that the fuel pump is working and delivering enough fuel to the fuel injectors.

The reason your 4.0L Ford vehicle is not starting is due to another reason. The fuel pump is OK. For more than troubleshooting options, accept a look at the post-obit tutorial:

  • How To Troubleshoot A No-Start Problem (4.0L Ford Explorer, Aerostar, And Mercury Mountaineer).