How To Troubleshoot A No Start (Ford 4.9L, 5.0L, 5.8L)

No Start 2: Checking For Fuel

Checking for fuel involves two separate tests. One is to check that the fuel pump is functioning and supplying the correct amount of pressure.

The other test is making sure that the PCM is activating the fuel injectors. This can easily be accomplished by using a Noid light to check for these ON/OFF activation pulses the PCM sends to the injectors.

Now, what makes testing the fuel pump pretty easy, is that your Ford pickup (van, SUV) has a Schrader valve located on the fuel injector rail to which you can attach a fuel pressure gauge. So, let's say you attached a fuel pressure gauge, you'll get one of two results:

For a step-by-step explanation on how to test the fuel pump, check out this tutorial: How To Test The Fuel Pump (Ford 4.9L, 5.0L, 5.8L).

NOTE: You can run down to your local AutoZone or O'Reilly Auto Parts and rent one or, you can buy one online. You can check out the following link: Actron CP7838 Professional Fuel Pressure Tester.

CASE 1: Fuel pressure is at specification This result confirms that the fuel pump is OK and doing its part. Also, this test result confirms that the following components are OK too:

• Fuel pump fuse.
• Fuel pump relay.
• Fuel pump inertia switch.

And so, there's no need to spend time testing them or money replacing them.

CASE 2: Fuel pressure is not present. This usually means that the pump has failed, but not always. I would recommend testing/checking the following before condemning the fuel pump:

• The fuel pump inertia switch.
  • Checking to see if the inertia switch has tripped is very important, before condemning the fuel pump.
  • If the inertia switch has been tripped, the fuel pump will not power up. So checking it and resetting it (if it has tripped) will save you from replacing a good fuel pump.
• Fuel pump power circuit.
  • The other very important thing to do, before condemning the fuel pump is to make sure it's getting power.
  • This can be done by tapping into the fuel pump's power circuit with a multimeter.
  • Once you're tapped in, have a helper crank the engine while you observe your multimeter in Volts DC mode. If voltage is present (12 Volts), then you have confirmed that the fuel pump fuse, fuel pump relay and inertia switch are working perfectly.
  • Confirming power to the fuel pump (with a multimeter) also verifies that the fuel pump has failed and needs to be replaced.
  • If no voltage is present, as your helper cranks the engine, then the cause of no fuel condition is due to either a bad fuse, fuel pump relay, or inertia switch.

No Start 3: Checking Engine Mechanical Condition

One of the most overlooked areas, when testing a hard to diagnose no start, is the mechanical condition of your 4.9L, 5.0L or 5.8L Ford car, pick up, van or SUV.

Checking the engine mechanical condition means an engine compression test.

• When performing an engine compression test, what you're looking for is an average compression reading of less than 90 PSI across all or the majority of the engine cylinders.
• If you have one or just two readings that are under 90 PSI your Ford vehicle will still start and run, albeit with a misfire condition.
• I've written a 'How To Do A Compression Test' article that you may find useful. Although this article is geared towards finding a hard to diagnose misfire (and written for the 4.6L and 5.4L engines), if you have never done a compression test, this article will help you: How To Test Engine Compression (4.9L, 5.0L, 5.8L).

No Start Summary

So many different things can cause a no-start condition that troubleshooting it can turn your Ford vehicle into a money pit, if you don't have a basic diagnostic strategy. The key to saving yourself time and money is checking for the basics first. The basics are spark and fuel.

To check the basics, you need tools. There's just no way around it. One of the analogies that I've always enjoyed repeating, about doing a job without the right tools is like trying to eat a bowl of soup with a fork.

So besides knowing what to test, you need tools to do those tests. You don't have to spend an arm and a leg, since you can buy a lot of diagnostics tools that are tailored for the pocket-books of the serious do-it-yourself-er. Here are some of the basic tools you'll need:

• Fuel pressure gauge.
• Spark tester.
• Compression gauge.
• Multimeter.

Related Test Articles

You can find a complete list of tutorials here: Ford 4.9L, 5.0L, 5.8L Index Of Articles.

Here's a sample of tutorials you'll find in the index:

• Ignition Coil Test -No Spark No Start Tests (Ford 4.9L, 5.0L, 5.8L)
• How To Test Engine Compression (4.9L, 5.0L, 5.8L).
• Manifold Absolute Pressure MAP Sensor Test (Ford 4.9L, 5.0L, 5.8L).
• Distributor Mounted Ignition Control Module Test (at: easyautodiagnostics.com).
• Fender Mounted Ignition Control Module Test (at: easyautodiagnostics.com).