Fuel System:
* Dirty Fuel Filter: A clogged fuel filter restricts fuel flow to the engine, leading to hesitation and poor performance. This is one of the easiest and cheapest things to check and replace.
* Bad Fuel Pump: A weak or failing fuel pump can't supply enough fuel under pressure, causing hesitation, especially under acceleration.
* Clogged Fuel Injectors: Clogged injectors deliver an inconsistent amount of fuel, leading to rough running and hesitation. Cleaning or replacing them might be necessary.
* Low Fuel Pressure: Problems anywhere in the fuel system (lines, regulator) can reduce pressure.
* Bad Fuel: Using low-quality or contaminated fuel can cause problems.
Ignition System:
* Worn Spark Plugs/Wires: These are essential for combustion. Worn plugs misfire, causing hesitation. Worn wires can cause poor spark delivery.
* Ignition Coil(s): A failing coil won't provide the necessary spark to one or more cylinders.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position; a faulty one can cause erratic timing and hesitation.
* Cam Position Sensor (CMP): Similar to the CKP sensor, but monitors the camshaft.
Air Intake System:
* Dirty Air Filter: A clogged air filter restricts airflow, leading to a lean fuel mixture and hesitation.
* Mass Airflow Sensor (MAF) Sensor: This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor provides inaccurate readings, leading to poor fuel mixture and hesitation.
* Vacuum Leaks: Leaks in the intake system disrupt the air/fuel mixture.
Other Potential Causes:
* Throttle Position Sensor (TPS): A faulty TPS provides incorrect information to the engine computer about throttle position.
* Transmission Issues (Automatic): Problems with the transmission, such as low fluid or worn components, can cause hesitation during acceleration.
* Oxygen Sensor(s): These sensors monitor the exhaust gases to help the computer adjust the air/fuel mixture. A faulty sensor can lead to poor performance.
* Computer Problems (PCM/ECM): In rare cases, a problem with the engine control module itself could be the cause.
Troubleshooting Steps:
1. Start with the easy and cheap fixes: Check and replace the air filter and fuel filter.
2. Check for diagnostic trouble codes (DTCs): Use an OBD-II scanner to read any codes stored in the engine computer's memory. These codes can point to specific problems.
3. Inspect visually: Look for obvious signs of damage, leaks, or loose connections in the fuel and air intake systems.
4. Test components: Testing specific components (fuel pressure, spark, etc.) often requires specialized tools and knowledge. A qualified mechanic can help with this.
Recommendation:
Unless you have experience working on vehicles, it's best to take your Blazer to a qualified mechanic for diagnosis and repair. Trying to troubleshoot this issue without the proper tools and knowledge could lead to further damage or incorrect repairs. The hesitation could be a symptom of a minor issue easily fixed or something more serious needing a thorough inspection.
