Testing a no-start condition, to find its root cause, involves 3 basic tests. In a nutshell: One is a spark test, the other is a fuel pressure test, and the last is a compression test.
Contents of this tutorial:
Difference Between A No-Start And A No-Crank Condition
To help you avoid any confusion and before I jump into the specifics of troubleshooting a no-start condition, let me tell you that a no-crank and a no-start condition are not the same thing. Here's a brief description that'll help you make sense of this tutorial:
Cranks But Does Not Start Condition: Means that your Nissan's starter motor is cranking the engine but the engine is not starting. This is usually due to a fault in the ignition system, or in the fuel system, or there's an engine mechanical problem (like a blown head gasket, etc.).
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 Nissan 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 (Nissan 1.6L, 1.8L).
No Start Condition Basics
The most basic and the most important thing you need to know, to begin troubleshooting the no-start condition, is that your Nissan Sentra's engine needs three things to start and run. These are:
- Air.
- Fuel.
- Spark.
When your Nissan Sentra cranks but does not start, it's because one of these 3 things is missing from the mix.
So, troubleshooting the problem requires that you and I check for spark (with a spark tester), check fuel pressure, and if necessary, check the engine's health with a compression test.
Checking For Spark
The ignition system is usually the culprit behind most ‘no-start’ conditions. The basic core components of the ignition system that fail and cause a no-start are:
- The ignition control module (ICM) -called the igniter.
- The ignition coil.
- The distributor cap.
- The distributor rotor.
Checking a no-start condition should start with a spark test. Making sure that all 4 cylinders are getting spark. This involves attaching a spark tester to a spark plug wire and having a helper crank the engine. If the spark plug wire sparks, then the test is repeated on the next 3 spark plug wires.
The purpose of this spark check is to make sure that all 4 spark plug wires are feeding spark to their respective cylinder. If spark is present at all 4 spark plug cables, then you can eliminate the ignition system as the culprit behind the no-start condition on your 1.6L Nissan Sentra. Your next diagnostic test step is to make sure that the fuel pump is OK (see next heading)
If you get a no spark test result on all 4 spark plug cables, then further testing is needed to find out the exact component that's causing the no spark issue. A no spark problem is usually caused by:
- Bad distributor cap.
- Bad ignition coil.
- Bad igniter.
