Fuel System:
* Fuel Pump: A failing fuel pump can't deliver enough fuel under pressure, especially when driving uphill or accelerating. The engine might sputter and die. When it's hot, the pump might struggle even more to restart. This is a very common cause.
* Fuel Filter: A clogged fuel filter restricts fuel flow, producing similar symptoms to a failing fuel pump. It's cheap and easy to replace, so it's always a good idea to check this first.
* Fuel Pressure Regulator: A faulty regulator might allow fuel pressure to drop too low, causing the engine to stall.
* Pick-up Tube in the fuel tank: If the pickup tube is clogged or has come loose in the tank, the fuel pump cannot draw fuel.
Ignition System:
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the computer the engine's rotational position. A faulty CKP sensor will cause the engine to stall unexpectedly and will often make it difficult or impossible to restart.
* Distributor Cap and Rotor: Worn or damaged components in the distributor can cause intermittent spark, leading to stalling. This is more likely in older vehicles like yours.
* Ignition Coil: A failing ignition coil can't produce the necessary high voltage for sparking.
* Ignition Module: This component controls the ignition coil. Failure can result in intermittent or complete loss of spark. (Some models have this, some use the coil directly in the distributor).
* Worn Spark Plugs and Wires: While less likely to cause a complete shutdown, worn spark plugs and wires can contribute to misfires and eventual stalling.
Other Potential Issues:
* ECM (Engine Control Module): A faulty ECM can cause a wide range of problems, including stalling and difficult starting. This is less common but a possibility.
* Temperature Sensor: An inaccurate coolant temperature sensor can cause the ECM to make incorrect fuel adjustments, potentially leading to stalling.
* Wiring Issues: Corrosion, loose connections, or damaged wiring can disrupt the flow of electricity to essential components, causing intermittent issues.
* Alternator: Although less likely to cause immediate shutdown, a failing alternator can leave the battery without a charge, leading to difficulty starting.
Troubleshooting Steps:
1. Check the fuel filter: This is the easiest and cheapest check. Replace it if it's dirty or damaged.
2. Listen for the fuel pump: Turn the ignition key to the "on" position (without starting the engine). You should hear the fuel pump prime for a few seconds. If not, the fuel pump or its wiring could be at fault.
3. Check the spark plugs: Check for spark. If there isn't consistent spark, focus on the distributor, ignition coil, module, and wiring.
4. Check fuel pressure: This requires a fuel pressure gauge and is best done by a mechanic. Low fuel pressure confirms fuel system issues.
5. Check for trouble codes: If your Blazer has a check engine light (CEL), a code reader can pinpoint potential issues. If the light is not on, issues may be intermittent and not be storing codes.
Recommendation:
Given the age of your vehicle and the complexity of the problem, it's best to take it to a qualified mechanic. They have the tools and experience to diagnose the problem accurately and efficiently, preventing further damage to your Blazer. Trying to troubleshoot this yourself without the proper equipment and knowledge could lead to more extensive repairs and wasted time and money.
