1. Fuel Delivery:
* Fuel Pump: The most likely culprit is a failing fuel pump. When you push the brake or put the vehicle in gear, the engine load increases, demanding more fuel. A weak fuel pump might not be able to keep up, leading to stalling.
* Fuel Filter: A clogged fuel filter can restrict fuel flow, causing similar symptoms.
* Fuel Lines: Cracked or leaking fuel lines can cause fuel starvation, especially under increased demand.
2. Ignition System:
* Distributor Cap & Rotor: Worn or cracked components in the distributor can lead to intermittent spark delivery, causing the engine to sputter or die.
* Spark Plugs & Wires: Foul or worn spark plugs and wires can cause misfires, especially under load.
* Ignition Coil: A failing ignition coil can produce weak or inconsistent spark, affecting engine performance.
3. Vacuum System:
* Vacuum Leaks: Small vacuum leaks can disrupt the engine's idle speed and cause it to stall under load.
* Vacuum Advance: A malfunctioning vacuum advance system in the distributor can cause timing issues, leading to poor performance.
4. Other Potential Issues:
* Transmission Linkage: If the transmission linkage is not properly adjusted, the engine might be receiving an incorrect signal when you shift into gear, leading to stalling.
* Throttle Position Sensor (TPS): A faulty TPS can provide inaccurate information to the engine control unit (ECU), disrupting engine operation.
* Idle Air Control (IAC) Valve: A dirty or malfunctioning IAC valve can cause idle speed issues, making the engine more susceptible to stalling.
Troubleshooting Steps:
1. Start with the basics: Check your fuel gauge to ensure you have enough fuel. Check for any obvious fuel leaks or loose connections.
2. Check the fuel pump: Listen for the fuel pump to activate when you turn the key to the "on" position. A loud humming sound indicates it's working. If you hear a weak or intermittent hum, or no sound at all, the pump may be failing.
3. Inspect the fuel filter: Look for signs of clogging or damage. Replace the filter if necessary.
4. Inspect the spark plugs and wires: Look for signs of fouling, wear, or damage. Replace them as needed.
5. Check the distributor cap and rotor: Look for cracks, corrosion, or wear. Replace them if necessary.
6. Check for vacuum leaks: Use a vacuum gauge to test for leaks in the vacuum system. Repair any leaks you find.
7. Check for loose or disconnected wiring: Make sure all electrical connections are secure.
Important Considerations:
* Safety: Be very careful when working with fuel and electrical systems.
* Expertise: If you're not comfortable working on your vehicle's systems, it's best to take it to a qualified mechanic.
* Professional Diagnosis: A mechanic can perform a comprehensive inspection and diagnose the problem more efficiently.
By systematically checking these areas, you can hopefully isolate the cause of your Chevrolet Blazer's stalling issue and get it running smoothly again.
