Fuel Pump Amperage Draw Test (2004-2010 4.0L V6 Ford Explorer And Mercury Mountaineer)

  • By: Abraham Torres-Arredondo
  • Created: 27 July 2025
  • Updated: 27 July 2025
  • Articl Id: 1852
Fuel Pump Amperage Draw Test (2004, 2005, 2006, 2007, 2008, 2009, 2010 4.0L V6 Ford Explorer And Mercury Mountaineer)

In this tutorial, I'm gonna show you how to find out the fuel pump's amperage draw by measuring its internal resistance on your 2004-2010 4.0L V6 Ford Explorer or Mercury Mountaineer.

Why does the fuel pump's amperage draw matter? Because if the pump is drawing too much current —even if it's running— it can (and will) fry the fuel pump driver module (FPDM).

This super easy test will let you catch a worn-out, high-draw pump before it takes out the FPDM or fry the new one you're about to install.

Contents of this tutorial:

APPLIES TO: This tutorial applies to the following vehicles:

  • 4.0L V6 Ford Explorer: 2004, 2005, 2006, 2007, 2008, 2009, 2010.
  • 4.0L V6 Mercury Mountaineer: 2004, 2005, 2006, 2007, 2008, 2009, 2010.

MORE FUEL PUMP DIAGNOSTIC RESOURCES: You can find fuel pump circuit wiring diagrams, related fuel pump tests, and the inertia switch tests in this section:

Why Check Fuel Pump Amperage Draw?

One of the things that isn't often mentioned about Ford's returnless fuel system —using a fuel pump driver module— is that, like any other PWM system that regulates the Ground side of the motor it controls (in this case the fuel pump, and in other systems, the electric radiator fan motors), they are super sensitive to excessive current draw from the component they're controlling.

By super sensitive, I mean that if the fuel pump draws too much amperage, it can —and will— burn out the fuel pump driver module (FPDM).

Even if the pump still runs and delivers pressure, if it's pulling more current than it should, it becomes a ticking time bomb for the FPDM —if it hasn't already fried it.

Here's why: all electric motors use a certain amount of current (Amps) as they run:

  • When new —and not defective— the current draw is minimal.
  • As they age, bushings and bearings wear out, as do the brushes inside the motor. This adds resistance to the rotating parts, causing the motor to draw more current to overcome it and keep working.
  • Eventually the motor dies and stops running, but in some cases, it keeps working while drawing more current than the fuse for its power circuit is rated to handle.
  • In a non-PWM setup, this just blows the fuse —no big mystery.
  • But in a PWM setup like in your Ford Explorer (or Mercury Mountaineer), the current delivered to the fuel pump isn't fuse-protected. So if the pump fails and starts pulling too much amperage, the internals of the FPDM overheat and get deep-fried.
    • This is absolutely the biggest design flaw of this system!!

I've seen plenty of cases where the FPDM was bypassed to check if the fuel pump runs —and it did, and the engine started. So the fuel pump driver module was diagnosed as bad and replaced.

Unfortunately, even though the fuel pump ran and built pressure, it was drawing too much amperage. And the new FPDM got fried within a day or two. Let me tell you —this misdiagnosis happens a lot!

That's why it's important to check the fuel pump's internal resistance and this can easily be done using a multimeter. The next step is to use Ohm's Law to calculate how much current the pump is drawing.

If the calculated amperage is at 15 Amps or more, you've got your culprit —and you just saved yourself from killing another FPDM down the road.

Checking The Fuel Pump's Internal Resistance

Checking The Fuel Pump's Internal Resistance. Fuel Pump Amperage Draw Test (2004, 2005, 2006, 2007, 2008, 2009, 2010 4.0L V6 Ford Explorer And Mercury Mountaineer)

Alright, let's get started:

  1. Disconnect the fuel pump driver module (FPDM) from its 6-wire connector.
  2. Set your multimeter to Ohms mode.
  3. Touch the red multimeter test lead to female terminal 4 of the FPDM connector.
    • Terminal 4 connects to the fuel pump's (+) terminal.
  4. Touch the black multimeter test lead to female terminal 2 of the FPDM connector.
    • Terminal 2 connects to the fuel pump's (-) terminal.
  5. Record the resistance your multimeter displays.
  6. Apply Ohms Law to calculate the amperage draw of the fuel pump:
    • Divide the fuel pump's resistance value into 12.5. The result of this calculation is the pump's amperage draw.
    • To be a little more specific: If the resistance of the fuel pump is 0.4 Ohms, the math would look like this: 12.5 ÷ 0.4 = 31.25. This means its amperage draw is 31.25 Amps.
  7. The calculated amperage draw of the fuel pump must not exceed 15 Amps.

More Fuel Pump Troubleshooting Help

FUEL PUMP PRESSURE TESTS:

FUEL PUMP INERTIA SWITCH TESTS:

FUEL PUMP DRIVER MODULE (FPDM) TESTS:

ENGINE NO-START DIAGNOSTICS:

FUEL PUMP CIRCUIT DIAGRAMS:

More 4.0L V6 Ford Explorer And Mercury Mountaineer Tutorials

I have written several more 4.0L V6 Explorer/Mountaineer specific test articles. You can find them all here:

The following tutorials are a sample of the articles you'll find in the index:

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