No Start 1: Checking For Spark
In my opinion (and in my experience), the most problematic area, when it comes to a cranks but does not start problem, is the ignition system.
So my recommendation is to test for spark right off the bat to see if spark is missing from the mix (air, fuel and spark).
The idea behind checking for spark is to see if all of the 8 engine cylinders are getting spark. Let's assume that you have already tested for spark and you observed one of the following spark test results:
CASE 1: Spark was present in all of the cylinders A spark result, if you're using a dedicated spark tester, tells you that:
- That the ignition control module is OK.
- That the PIP (Profile Ignition Pickup) sensor is OK.
- That the ignition coil is doing dandy.
- You don't have to spend any time testing them or any money replacing them.
So, if you do have spark, the next step in your troubleshooting is to verify fuel pressure. Go to No Start 2: Checking Fuel.
CASE 2: Spark was NOT present in all of the cylinders A number of things can cause this no spark result... so this what I would suggest:
- Test the ignition coil.
- Check for spark directly on the ignition coil tower.
- The distributor cap and rotor can go BAD and not deliver the spark that the ignition coil is delivering to them... so testing for spark directly on the ignition coil is the best way to check this.
- If you do get spark from the ignition coil's tower, then now you know that the distributor cap and rotor are fried and need to be replaced.
- You can find the ignition coil test here: Ignition Coil Test -No Spark No Start Tests (Ford 4.9L, 5.0L, 5.8L).
- Test the ignition control module..
- The ignition control module is the one that activates the ignition coil.
- You can test the ignition control module on your Ford vehicle.
- You can find the ignition control module test here:
- Test the PIP sensor..
- The PIP signal is at the heart of the ignition system and it triggers the ignition control module to start activating the ignition coil.
- The PIP signal is also used by the PCM to start injecting fuel into the cylinders.
- You can test the PIP sensor on your Ford vehicle.
- You can find the PIP sensor test here (the test is bundled in with how to test the ignition control module):
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).