How To Check for Spark When an Engine Does Not Start

By | January 23, 2020

How To Check for Spark When an Engine Does Not Start
If you find yourself with a vehicle that the engine does not start the first things to check for is spark and gas.

All mechanics will eventually find themselves with this problem and need to diagnose the electrical problem.

Knowing whether an engine has spark will quickly help narrow the problem with a vehicle that does not want to start.

What is Engine Spark?
The hart of a combustible engine is gas for fuel and spark to ignite it.

Gas is fed into a combustible chamber and a spark is fired to set it off creating a small controlled explosion.

These small explosions send a piston downward driving a crankshaft and a running engine.

While engines, especially new ones, can be complex this basic combination of fuel and spark is what makes any engine run.

Checking if an engine is getting spark can quickly rule out or point to the part of a vehicle that has a problem.

The first step when fixing any engine is troubleshooting the problem narrowing it down to the bad part in steps.

Tools need to Test for Spark
There is a way to test for spark without using a tool but a spark plug testing tool makes the job much easier.

A spark plug tool also reduces the risk of a shock from the coil high voltage.

With that said I have tested for spark many times with no spark plug testing tool but they are low-cost items that makes the job much easier.

If you do not have the tool the spark plug will need to be removed with the tip held close to a ground such as the engine block to see if a small spark flashes.

Spark Plug Testing Tool on Amazon
Ram-Pro in-Line Spark Plug Engine Ignition Tester, 6-12 Volt Fool-Proof – Pick Up Coil/Armature Diagnostic Detector Tool – for Automotive, Car, Lawnmower, Small & Big Internal/External Engines


How To Check for Spark on an Engine

  1. Locate the spark plugs and remove one of the spark plug wires.
  2. How To Check for Spark on an Engine Step 1

  3. Insert the spark plug wire into a spark plug testing tool.
  4. How To Check for Spark on an Engine Step 2

  5. Insert the other side into the spark plug hole.
  6. How To Check for Spark on an Engine Step 3

  7. The indicator light will flash rapidly if there is a spark.
  8. How To Check for Spark on an Engine Step 4

  9. If there is no spark the light will not flash.

The above steps will test an engine for spark.

If there is spark it doesn’t completely rule out a spark problem but in most cases, there will be another issue.

If there is no spark each component will need to be tested to see which part is causing the no spark issue.

Older cars and trucks are much simpler to troubleshoot with a coil, distributor, rotor, possibly points, spark plug wires, and ignition hot wire, the main components to test.

New cars and trucks have different system to manage parts with coil packs, spark plug wires, fuses, cam sensor, crankshaft sensor the first things to look at.

Of course, every manufacturer is different and may have designed things differently.

While there may be different systems most all vehicle engines can be tested for spark the same way.



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