How To Test The Fuel Pump (2003, 2004, 2005, 2006, 2007 4.8L, 5.3L, 6.0L Chevrolet Express And GMC Savana)

Testing the fuel pump, on your 2003-2007 V8 equipped Chevrolet Express (GMC Savana) van, can easily and accurately be done with a fuel pressure test gauge.

In this tutorial I'll explain how it's done so that you can find out if the fuel pump is bad or not.

APPLIES TO: This tutorial applies to the following vehicles:

Chevrolet:

  1. Express (1500):
    1. 4.8L, 5.3L: 2003, 2004, 2005, 2006, 2007
  2. Express (2500):
    1. 4.8L, 5.3L, 6.0L: 2003, 2004, 2005, 2006, 2007
  3. Express (3500):
    1. 4.8L, 6.0L: 2003, 2004, 2005, 2006, 2007

GMC:

  1. Savana (1500):
    1. 4.8L, 5.3L: 2003, 2004, 2005, 2006, 2007
  2. Savana (2500):
    1. 4.8L, 5.3L, 6.0L: 2003, 2004, 2005, 2006, 2007
  3. Savana (3500):
    1. 4.8L, 6.0L: 2003, 2004, 2005, 2006, 2007

RELATED WIRING DIAGRAM:

  1. Fuel Pump Wiring Diagram (2003-2007 V8 Chevrolet Express, GMC Savana).

Common Symptoms Of A Bad Fuel Pump

A fuel pump will generally fail in one of two ways:

  1. The fuel pump stops working completely (producing no fuel pressure) and causes an engine no-start problem.
  2. The fuel pump fails slowly and produces only enough fuel pressure to start the engine but not enough to drive the vehicle on the road.

These are the symptoms that you're going to see when the fuel pump has failed or is starting to fail:

  1. The engine cranks but does not start.
  2. The engine starts but stalls after a few seconds.
  3. The engine starts but as soon as you step on the accelerator pedal the engine stalls.
  4. Lack of power while driving the vehicle.
  5. Explosions can be heard coming from the intake manifold when you step on the accelerator while the engine is under load.
  6. The check engine light is on and lean air fuel mixture trouble codes are stored in the fuel injection computer's memory.

Where To Buy A Fuel Pressure Test Gauge

You can buy a fuel pressure test gauge just about anywhere and is one of the most important tools any serious DIY'er should have in his/her tool box.

The fuel pressure test gauge kit that'll connect to your Chevy or GMC pickup's Schrader valve and that I recommend for its low price and durability is the: Actron CP7838 Professional Fuel Pressure Tester.

All of the following fuel pressure test gauge kits will help test your Chevrolet Silverado or GMC Sierra's fuel pump:

TEST 1: Testing The Fuel Pressure With A Fuel Pressure Test Gauge

Testing The Fuel Pressure With A Fuel Pressure Test Gauge. How To Test The Fuel Pump (2003, 2004, 2005, 2006, 2007 4.8L, 5.3L, 6.0L Chevrolet Express And GMC Savana)

To test the fuel pump, we're going to connect a fuel pressure test gauge to the Schrader valve located on the fuel injector rail.

The illustration above and the photo at the beginning of the tutorial show the location of the Schrader valve and what it looks like on your Chevrolet Express (GMC Savana).

NOTE: You'll need a fuel pressure tester that can connect to the Schrader valve. If you don't have one, take a loot at my recommendations here: Where To Buy A Fuel Pressure Test Gauge.

FUEL PRESSURE SPECIFICATION: The fuel pressure specification for the 2003-2007 4.8L, 5.3L, 6.0L Chevrolet Express (GMC Savana) is 55 to 62 PSI. Flex fuel engines: 48-54 PSI.

These are the test steps:

  1. 1

    Connect your fuel pressure tester to the Schrader valve.

  2. 2

    Have your helper crank the engine while you observe the needle on the fuel pressure tester gauge.

  3. 3

    The fuel pressure tester should give you a reading between 55 to 62 PSI.

Let's examine your test results:

CASE 1: The fuel pressure is within the indicated specification. This is the correct test result.

This test result confirms that the fuel pump in your Express (Savana) van is OK (functioning correctly).

CASE 2: You got 0 psi fuel pressure. This test result lets you know that the fuel pump is defective and is causing the engine to not start.

Before you replace a fuel pump make sure that the fuel pump relay and fuel pump fuse are supplying power to the fuel pump when the engine is being cranked.

If battery power is available to the fuel pump, when cranking the engine, then you can confidently conclude that the fuel pump is defective and that it needs to be replaced.

CASE 3: The fuel pressure was below the indicated fuel pressure specification. This test result lets you know that even though the fuel pump is supplying some fuel it's not supplying enough to have the engine run optimally.

This is an indication that the fuel pump is failing and needs to be replaced.

Chevrolet Vehicles:

  • Express Van 4.8L, 5.3L, 6.0L
    • 2003, 2004, 2005, 2006, 2007

GMC Vehicles:

  • Savana Van 4.8L, 5.3L, 6.0L
    • 2003, 2004, 2005, 2006, 2007