How To Diagnose A No-Start Problem (3.1L V6 Buick, Oldsmobile)

Troubleshooting an engine no-start problem can feel overwhelming since quite a few issues can cause it.

But in reality, there is a 'method to the madness' of troubleshooting and resolving such a problem. In this article, I'll share some of my knowledge and experience on how to find the exact cause of the engine's no-start problem.

APPLIES TO: This tutorial applies to the following vehicles:

• 3.1L V6 Buick Century: 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.
• 3.1L V6 Buick Regal: 1994, 1995, 1996.
• 3.1L V6 Buick Skylark: 1994, 1995, 1996.
• 3.1L V6 Oldsmobile Achieva: 1994, 1995, 1996, 1997, 1998.
• 3.1L V6 Oldsmobile Cutlass: 1997, 1998, 1999.
• 3.1L V6 Oldsmobile Cutlass Ciera: 1994, 1995, 1996.
• 3.1L V6 Oldsmobile Cutlass Supreme: 1993, 1994, 1995, 1996, 1997.

Difference Between A No-Start And A No-Crank Condition

Before we start, and to get the most out of this article, I want to explain the difference between an engine no-start problem and an engine no-crank problem.

Engine No-Start Problem: The starter motor turns the engine over, but the engine won't start. The engine no-start issue is usually due to a bad fuel pump, bad CKP sensor, bad ignition control module, etc.

Engine No-Crank Problem: In this type of problem, the starter motor does not come out to play. In other words, it does not crank the engine. This issue is usually due to a bad starter motor or a bad or discharged battery.

So if you turn the key and the starter motor does not crank the engine, then you'll need to troubleshoot the starter motor:

• How To Test The Starter Motor (1990-2004 3.1L V6 Buick, Oldsmobile).

Engine No-Start Diagnostic Basics

To successfully diagnose the exact cause of an engine no-start issue, it's important to know that the engine need three things to start. These three things are:

• Air (compression).
• Fuel.
• Spark.

If any one of these is missing, the engine will not start when you turn the key to start it.

Here are some more specifics/details:

1.)  Ignition System

1. The ignition system is the one responsible for creating and delivering spark. Without spark, the engine will crank but not start.
2. The ignition system of the GM 3.1L equipped vehicles covered by this article use a distributor-less ignition system. More specifically, it uses a coil pack type ignition system.
3. In my experience, the most common component failures of the ignition system that cause a no-start no-spark condition are:
   • Bad ignition control module (ICM).
   • Bad ignition coil pack.
   • Bad crankshaft position sensor.
   • Bad camshaft position sensor.
4. All of the above ignition system components can be tested in a systemic way to find out exactly what has failed (if indeed something has).

2.)  Fuel System

• The electric fuel pump (located in the fuel tank) is the key component that supplies the fuel injectors with the fuel needed to inject gasoline into the cylinders.
• When the fuel pump fails, it will cause a no-start condition.
• Thankfully, we can test the fuel pump with a fuel pressure gauge to make sure it has really fried.

3.)  Engine Mechanical System

1. 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.
2. Although rare, internal engine mechanical problems can and do cause no-start problems.
3. Possible internal engine problems are:
   • Blown head gasket.
   • Blown engine.

4.)  Anti-Theft System

1. The vehicles covered in this tutorial have the PASS-Key passive theft-deterrent system integrated into the PCM or body control module (BCM).
2. The PASS-Key system can be identified by the use of a resistor pellet on the ignition switch key.
3. When a malfunction occurs in one of the components that make up the anti-theft system (usually the lock cylinder), 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. The PCM has disabled the fuel injectors after the engine has started, causing the engine to stall after a few seconds of run time.
4. PASS-Key system failures are a very, very common cause of no-crank problems and no-start problems.

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 bad 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.

The diagnostic strategy involves performing four essential tests to find out what's causing the engine not to start:

• Ignition system test: spark test.
• Fuel system test: fuel pressure test.
• Engine compression test.
• Blown head gasket test.

In the following subheadings you'll find a basic testing guide that you can use to find out what's behind your 3.1L V6 Buick or Oldsmobile's no-start problem.

What Tools Do I Need?

You can troubleshoot a no-start problem with a few basic tools. Yep, you don't need any exotic or expensive testing equipment.

The basic tools that you're going to need are:

• 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 article, I haven't included it (a scan tool) in any of the suggested tests because they can be done without one.

The spark tester I have in my toolbox and always use:

Fuel pressure testers I have in my toolbox and that I use:

STEP 1: Testing The Ignition System For Spark

I'm going to recommend that you start your engine no-start troubleshooting with the ignition system first.

What you want to do is verify that all six spark plug wires are delivering spark to the spark plugs.

To accomplish this, you'll need to test all six spark plug wires for spark with a dedicated spark tester. Using any other method to test for spark (that doesn't involve a spark tester) opens up the possibility of getting a false test result, which could have you wasting time and money on parts the car doesn't need.

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).