No Start 4: Checking Engine Mechanical Condition
One of the most overlooked areas, when testing a hard to diagnose no-start, is the mechanical condition of your 4.3L, 5.0L, 5.7L GM 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 GM 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, if you have never done a compression test, this article will help you: 4.3L, 5.0L, 5.7L Engine Compression Test.
No Start Summary
So many different things can cause a no start condition that troubleshooting it can turn your GM 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.
Related Test Articles
You can find a complete list of tutorials here: GM 4.3L, 5.0L, 5.7 Index Of Articles. Below, is a sample of articles you'll find in this index of articles:
- How To Test The Engine Compression (GM 4.3L, 5.0L, 5.7L).
- How To Test The Crank Sensor (GM 4.3L, 5.0L, 5.7L).
- How To Test A Misfire / No Spark-No Start Condition (4.3L, 5.0L, 5.7L 96-04) (at: easyautodiagnostics.com).
- How Can I Tell If My 4L60-E Transmission Is Bad?
- Troubleshooting A Blown Head Gasket (GM 4.3L, 5.0L, 5.7L).
- Shift Solenoid A And B Tests (GM 4.3L, 5.0L, 5.7L).
If this info saved the day, buy me a beer!