Testing a cranks but does not start condition on your GM 2.3L or 2.4L Quad-4 engine isn't as hard as you might think.
In this tutorial, I'll explain the basics of what causes a cranks but does not start condition and the basic tests you can do to get to the bottom of the problem (and solve it).
Here are the contents of this article at a quick glance:
- Difference Between A No Start And A No Crank Condition.
- No Start Condition Basics.
- No Start 1: Checking For Spark.
- No Start 2: Checking For Fuel.
- No Start 3: Checking Engine Mechanical Condition.
- No Start Summary.
- Related Test Articles.
Difference Between A No Start And A No Crank Condition
Before I jump into the specifics of what causes a no start condition, I want to take the time to explain two terms you might have read or heard:
Cranks but Does Not Start Condition: In this type of problem, the engine does turn over when you turn the key to start it... but it just don't catch and run.
In other words... the starter motor does work and does crank the engine, but the engine refuses to start.
The info in this tutorial applies to this type of problem usually caused by the ignition system, fuel system, or engine mechanical condition.
Does Not Crank Condition: Means that the engine is not cranking when you turn the key to crank the engine. In other words, the engine doesn't turn over at all. This is usually due to a bad starter motor, bad ignition switch, bad neutral safety switch, or the engine is locked up.
If your Quad-4 equipped GM car doesn't crank and you suspect the starter motor, here's a tutorial that'll help you test it: How To Test The Starter Motor (GM 2.4L Quad 4).
No Start Condition Basics
One of the most important things you need to know, when diagnosing/troubleshooting a no start problem on your Quad-4 equipped car... is that the problem will be caused by the lack of 3 specific things. These 3 specific things are:
That's right!.... When your Quad-4 equipped GM car cranks but does not start...it's because one of these 3 things is missing from the air/fuel mixture the engine needs to start and stay running. It's as simple as this! I know, I know... I may be over-simplifying it all... but knowing that only one of three things is missing really helps to put the problem into perspective!
So, with this knowledge under our belts... you can now plan a specific testing strategy to find out what is missing and keeping your car from starting.
This testing strategy includes: testing for spark, testing the fuel pump, and possibly testing the engine's compression.
I'll go into more specific details in the following headings:
1.) Ignition System
- The Ignition System is the one tasked with creating and delivering spark to each of the 6 cylinders. Without spark, the engine will crank but not start.
- The Ignition System of the Quad-4 equipped GM car vehicles covered by this article use a distributor-less ignition system where 2 ignition coils feed the 4 cylinders with spark.
- In my experience, the most common component failures, of the Ignition System that cause a no start no spark condition are:
- Ignition control module (ICM).
- Ignition coil.
- Crankshaft position sensor.
- All of the above Ignition System components can be tested in a methodical way to find out exactly what has failed (if indeed something has).
2.) Fuel System
- The Fuel System is the one responsible with supplying the engine with fuel.
- The Fuel System component that causes the majority of no start no fuel problems:
- Fuel pump.
- The fuel pump can be tested to make sure it has really fried using a fuel pressure gauge.
3.) Engine Mechanical System
- The components that are responsible for drawing in the air the engine needs are the: engine pistons, cylinder head valves, and all the other related components like: timing chain, etc.
- Although rare, internal engine mechanical problems can and do cause no start conditions.
- Possible internal/external engine problems are:
- Blown head gasket.
- Blown engine.
- Busted timing chain.
OK, the list of possible things that can go wrong looks pretty long... but it is rare to see (or have) two different components go BAD from two separate systems at the same time.
The cool thing is, is that there is a diagnostic strategy that you can use to figure out exactly what's wrong with your particular no start problem. Let's find out more about it in the next subheading...