* Incorrect Tune-up: While a tune-up was performed, something may have been done incorrectly. This could include:
* Incorrect spark plug gap: Too wide or too narrow a gap can prevent proper ignition.
* Worn or faulty distributor cap and rotor: Even new parts can be defective.
* Incorrect timing: The ignition timing needs to be precisely set; even a few degrees off can prevent starting.
* Improper carburetor adjustment (if applicable): A carburetor needs to be properly adjusted for air/fuel mixture.
* Faulty ignition coil: A weak or failing coil won't provide enough voltage for reliable ignition.
* Incorrectly installed components: A simple mistake during reassembly can cause a starting problem.
* Issues Unrelated to the Tune-Up: The tune-up addresses ignition and fuel delivery, but other systems can prevent starting.
* Fuel pump failure: The fuel pump might not be delivering fuel to the carburetor or fuel injectors.
* Clogged fuel filter: Restricted fuel flow can prevent the engine from starting.
* Faulty fuel injectors (if fuel-injected): Clogged or malfunctioning injectors need attention.
* Low compression: Worn piston rings or valve problems can lead to insufficient compression to start.
* Dead battery: A weak battery might not have enough power to crank the engine over.
* Faulty starter: The starter motor itself might be failing.
* Broken or loose wires: A simple loose connection can prevent the engine from starting.
* Neutral safety switch (automatic transmission): The car might not start if the transmission isn't in Park or Neutral.
* Other Mechanical Issues:
* Seized engine: An engine that's seized due to lack of lubrication won't turn over.
Troubleshooting Steps:
To diagnose the problem, you should systematically check the following:
1. Battery Voltage: Test the battery's voltage.
2. Starter Motor: Listen for the starter to engage. If it clicks weakly or not at all, the starter might be faulty.
3. Fuel Delivery: Check if fuel is reaching the carburetor or fuel injectors.
4. Spark: Check for spark at the spark plugs.
5. Compression: A compression test will reveal if the engine has sufficient compression.
6. Verify all connections: Check all wires and connections for security and damage.
If you're not comfortable performing these checks yourself, it's best to take the car to a qualified mechanic for proper diagnosis and repair. Simply stating "complete tune-up" doesn't guarantee the resolution of all potential starting problems.
