Engine Troubleshooting Overview

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Revision as of 09:18, 12 December 2006

Introduction

Trouble shooting is only a process of elimination and provided the procedure is carried out correctly and systematically an accurate diagnosis of the trouble can be made in the minimum amount of time.

For an internal combustion engine to run there are three basis requirements, these are ignition, fuel and compression. There are other factors of course, but as a rule an engines failure to start can be attributed to a fault in one or more of these three systems.

The most likely cause of an engine wont start issue is an ignition or electrical failure first followed by fuel, with mechanical or compression failure the least common.

Before getting into ignition troubleshooting it is worth checking, is there fuel in the fuel tank? If yes begin the ignition/electrical diagnosis.

Ignition and Electrical Systems checks

Switch on the ignition and check for warning lamp illumination.

Operate the starter switch and check that the starter rotates the engine at a steady speed.

Switch on the headlamps and check for good light intensity.

Should the lamps not illuminate or the starter motor not turn the engine, carry out the following action:

(a) Remove the battery terminals and clean both terminals and posts. Refit the terminals and tighten firmly but not excessively.

(b) Check that the earth lead from the battery to the engine and body frame is not broken and that the connections are clean and secure.

(c) Check that the lead from the battery to the starter motor or starter solenoid is intact and with a clean and secure connection.

(d) Where necessary carry out repairs to (b) and (c)

Again carry out the check procedure. Should the starter motor still not operate, or the lamps illuminate, then one or more of the following faults may be the cause:

• No starter motor operation or lights: Battery flat or defective.
• Lights illuminate but no starter operation: Starter motor drive jammed in mesh with flywheel ring gear. Starter motor or solenoid defective. Ignition/starter switch faulty.
• Lights dim and starter motor operation sluggish: Discharged battery or fault in starter motor. Battery flat due to broken fan belt or defective alternator. Faulty battery due to cell breakdown.

If the battery and starter motor operation prove satisfactory but the engine still fails to start continue as follows: