Engine Management System, Engine doesn't

Troubleshooting Guide: Top 10 reasons why the engine doesn’t start

 | 5 minutes read

What are the reasons the engine doesn't start:

There are a number of reasons if your car or bike’s engine doesn't start. We can split these into the issues related to the electrical system, fuel system (Petrol / Diesel) or a mechanical breakdown inside the engine.

The troubleshooting diagnosis for Petrol and diesel engines differ from each other. In this article, we look at common problems and solutions as to why both petrol and diesel engine doesn't start.

Troubleshooting Guide: Engine doesn’t start (Fuel system, for both petrol and diesel):

Let's look at the common problems and solutions in fuel system when the engine doesn't start.



No fuel: Seriously? If the fuel meter doesn’t work properly or is faulty, you may not know if there is enough fuel to start the engine. If the fuel meter needle is at the bottom-most position, it means there is not enough fuel. Similarly, if it is stuck at the top-most position, the meter is faulty. Refill at least 1-liter fuel in case of a bike and 5 liters in case of a car if you can’t see any reading on the fuel meter.
Water in fuel tank: This happens during the rainy season. If by any reason water seeps into the fuel tank and thereby into the fuel system, your engine may not start. Remove the fuel tank and empty the contents completely. Refill with fresh/clean fuel. You may also need to remove and clean injectors or carburetor as the case may be.
Choked Fuel filter/fuel pump failure: Replace the fuel filter element as recommended by the manufacturer. Replace fuel pump.
Restricted Air-flow: An engine doesn’t start because of restricted air-flow to the engine. This may be because of obstructions such as dry leaves in the front grill air vent or choked air-filter. Remove obstructions in the air intake ducts.
Choked Air-filter. Remove the air filter element and clean / replace as recommended by the manufacturer.

Note the lights on the dashboard. If 'check engine' light remains on, it means there is some issue with the engine management system. In that case, you may need to approach the competent person.

Troubleshooting Guide: Engine doesn’t start (for Diesel Engines):

Fuel Injection Pump (FIP) Solenoid: If the connection to the solenoid which actuates the fuel supply to the FIP is snapped the diesel engine doesn’t start. Connect the wire to the FIP solenoid and secure firmly / Replace blown solenoid fuse.
Choked injectors: If your engine’s injectors are choked, then the engine doesn’t start. The carbon deposits on the injector tips and chokes them. This results in the improper/inadequate injection. Remove and clean the injectors. Check for correct injection pressure.

Troubleshooting Guide: Engine doesn’t start (Electrical system):

Let's look at the common problems and solutions in electrical system when the engine doesn't start.

Engine doesn't start: Electric Starter Motor cut-sectional view
Engine doesn't start: Electric Starter Motor


The battery doesn’t have enough charge: If your car/bike’s battery goes down below 9 volts, it may not start the engine. A battery must supply at least 10 volts to crank the engine. Recharge the battery.
Battery cable loose: In case if your car/bike’s battery cable is loose, then it may not start the engine. In this case, when you turn on the ignition switch; you may hear a clicking sound. Tighten the battery terminals adequately.
Battery terminals eroded: After prolonged use, the battery terminals get eroded, resulting in weak current output. Remove the battery terminals and clean. Apply petroleum jelly to prevent erosion.
Worn contact points of starter motor: The starter motor requires high voltage current. If the solenoid contact points of the starter motor are worn, then it may not be able to pass the current required to crank the engine. In this case, when you try to start; you may hear chattering sound. Remedy: Remove the starter motor and rub the contact points with emery paper/sand paper to remove high-spots.
Weak or NO spark: If the spark plug of your car or bike is worn out or spoiled, then the spark may not have the strength required to ignite the fuel. The unburnt fuel/oil particles accumulate in the air-gap between spark plug terminals which results in weak / no spark. Clean / replace the spark plug as the case may be. Additionally, maintain the air-gap as recommended by the manufacturer.
Blown fuse: Check for blown ignition fuse and replace.

Troubleshooting Guide: Engine doesn’t start (mechanical components):

Choked silencer: If the silencer/exhaust tail-pipe is choked or has some obstruction, then also the engine doesn’t start. Remove any obstruction in the tail-pipe and clean.
Mechanical breakdown inside the engine: There could be multiple reasons for the mechanical breakdown of the engine such as seizure of pistons, broken valves, bent connecting rods, broken pulleys etc.

A poorly maintained engine may cause such mechanical failures. Thus, it needs thorough inspection and analysis of the engine to determine the exact nature of the cause.


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