Several different issues can cause an engine no-start problem, which could make you think that troubleshooting such a problem is too difficult. Let me tell you that nothing could be further from the truth!
In this article, I'll explain my process for diagnosing a no-start problem which will help you troubleshoot the engine no-start problem in your vehicle.
Contents of this tutorial:
- Difference Between A No-Start And A No-Crank Condition.
- Engine No-Start Diagnostic Basics.
- How Can I Troubleshoot A No-Start Problem?
- What Tools Do I Need?
- STEP 1: Testing The Ignition System For Spark.
- STEP 2: Testing The Fuel Pump's Pressure.
- STEP 3: Anti-Theft System Checks.
- STEP 4: Making Sure The Engine Has Good Compression.
- STEP 5: Checking For A Blown Head Gasket.
- No-Start Troubleshooting Summary.
- More 3.4L V6 Buick, Oldsmobile Tutorials.
APPLIES TO: This tutorial applies to the following vehicles:
- 3.4L V6 Buick Rendezvous: 2002, 2003, 2004, 2005.
- 3.4L V6 Oldsmobile Alero: 1999, 2000, 2001, 2002, 2003, 2004.
- 3.4L V6 Oldsmobile Silhouette: 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004.
Difference Between A No-Start And A No-Crank Condition
It's essential to know the difference between a no-start problem and a no-crank problem.
In an engine no-start problem, the starter motor works. Specifically, when you turn the key to crank and start the engine, the starter motor turns the engine over, but the engine doesn't start.
In a no-crank problem, the starter motor does not work. Nothing happens when you turn the key to the crank and start the engine.
So, if your vehicle is experiencing an engine no-crank problem, this tutorial will not help. Instead, what you'll need to do is to test the starter motor.
Engine No-Start Diagnostic Basics
The six cylinders of the 3.4L V6 engine need three things for the engine to start. These three things are:
- Air (compression).
When one of these three things is missing from all six cylinders, the engine is not going to start.
1.) Ignition System
- The coil pack type ignition system on your 3.4L V6 engine is responsible for creating and delivering spark. Without spark, the engine will crank but not start.
- In my experience, the most common component failures of the ignition system that cause a no-start no-spark condition are:
- A bad ignition control module (ICM).
- A bad ignition coil pack.
- A bad crankshaft position sensor.
- A bad camshaft position sensor.
- All of the above ignition system components can be tested systematically to find out exactly what has failed (if indeed something has).
2.) Fuel System
- The electric fuel pump (located in the fuel tank) supplies the gasoline the fuel injectors spray into the cylinders.
- When the fuel pump fails, it will cause a no-start condition.
- The fuel pump is easily tested with a fuel pressure gauge. Which helps in finding out if it's bad or not.
3.) Engine Mechanical System
- The engine pistons and cylinder head valves (and all the other related components like the timing chain, etc.) are responsible for the induction of the fresh air the engine needs for the combustion process.
- Although rare, internal engine mechanical problems can and do cause no-start problems.
- Possible internal engine problems are:
- 0 PSI compression in most if not all cylinders.
- A blown head gasket.
- A blown engine.
4.) Anti-Theft System
The vehicles covered in this tutorial have the PASS-Key III or Passlock passive theft-deterrent system integrated into the PCM or body control module (BCM).
- PASS-Key III System:
- The PASS-Key III system can be identified by the use of a transponder located on the plastic end of the key.
- Vehicles that use the PASS-Key system:
- 2002-2005 3.4L Buick Rendezvous.
- 2000-2005 3.4L Oldsmobile Silhouette.
- When a malfunction occurs in one of the PASS-Key III system components, one of two things happen:
- The engine won't crank over to start. The PCM has disabled the starter motor.
- The engine cranks but does not start, or it starts and runs but shuts off after a few seconds. In both of these cases, the PCM has disabled the fuel injectors.
- PASS-Key III system failures are a very, very common cause of no-crank problems and no-start problems.
- Passlock System:
- The Passlock system can be identified by the use of a transponder located on the plastic end of the key.
- Vehicles that use the Passlock system:
- 1999-2004 3.4L Oldsmobile Alero.
- When a malfunction occurs in one of the Passlock system components, the engine cranks but does not start, or it starts and runs but shuts off after a few seconds. In both of these cases, the PCM has disabled the fuel injectors.
How Can I Troubleshoot A No-Start Problem?
As you can see, quite a few things, when they fail, can cause a 'cranks but does not start' problem. I don't mean to imply that several things can go wrong all at once since it's rare to see (or have) two different components go bad from two separate systems simultaneously.
The light at the end of the tunnel is that there is a diagnostic strategy that you can use to figure out exactly what's wrong with your particular no-start problem.
To find out which of these three things are missing and keeping the engine from starting, we can perform four tests.
These four tests are:
- Ignition system test: spark test.
- Fuel system test: fuel pressure test.
- Engine compression test.
- Blown head gasket test.
What Tools Do I Need?
Although you don't need any expensive or exotic diagnostic testing equipment to troubleshoot an engine no-start problem, you will need a few essential tools.
- A spark tester.
- A fuel pressure tester.
- An engine compression tester.
- A multimeter.
- A code reader.
For the ignition system spark tests, I'm going to recommend that you use an HEI spark tester.
This is the most accurate spark tester that you can buy and it doesn't cost an arm and a leg. You can find out more about it and where to buy it here: HEI Spark Tester (at: easyautodiagnostics.com).
You'll notice that I didn't include a scan tool in the list. But if you have one, I can tell you that it'll come in handy. Why? Because some of the components that cause a no-start condition can leave a specific trouble code (when they fail).
In this tutorial I haven't included it (a scan tool) in any of the suggested tests because they can be done without one.
STEP 1: Testing The Ignition System For Spark
Quite a few ignition system components can cause the engine not to start.
The first step in finding out which ignition system component has failed is performing a spark test of all six spark plug wires.
The ignition system is NOT causing the no-start problem if:
- Spark is present at all spark plug wires.
With all spark plug wires delivering spark to the cylinders (spark plugs), you can conclude that the ignition system is NOT causing the engine no-start problem.
You can also conclude that:
- The crankshaft position (CKP) sensor is good.
- The ignition control module (ICM) is good.
- The ignition coil pack is good.
Since the ignition system is creating and feeding spark to the engine cylinders, the next test steps are to test the fuel pump's pressure. Go to: STEP 2: Testing The Fuel Pump's Pressure.
The ignition system IS THE CAUSE of the no-start problem if:
- You got NO spark at all spark plug wires.
The components that can cause this no-spark problem are:
- A bad crankshaft position (CKP) sensor.
- A bad ignition control module (ICM).
- In some rare cases, a bad ignition coil pack.
Your next steps are to:
- Test the crankshaft position (CKP) sensor (to make sure that the ignition control module is receiving a CKP signal).
- Test the ignition control module (ICM).
I've written a tutorial that'll help you test the ignition system (and find out if it's behind your engine's no-start problem). You can find it here: Testing The Ignition Module and Crank Sensor (GM 3.1L, 3.4L) (at: easyautodiagnostics.com).