To diagnose the problem, you'll need to get the trouble codes read. Here are your options:
* OBD1 Scanner: Your 1991 Silverado uses OBD1, which is an older diagnostic system. You'll need an OBD1 scanner specifically designed for GM vehicles from that era. These can be found online or at some auto parts stores. The scanner will provide a code (or several codes) that pinpoint the likely cause of the problem.
* Auto Parts Store: Many auto parts stores will scan your vehicle's codes for free. This is a convenient option to get an initial diagnosis.
* Mechanic: A qualified mechanic will have the tools and expertise to diagnose and repair the problem effectively. This is often the best option, especially if you're not comfortable working on your vehicle yourself.
Possible Causes of a Flashing CEL (Misfire) on a 1991 Silverado:
* Ignition System: Problems with spark plugs, ignition wires, distributor cap, rotor, or ignition coil are common causes of misfires. Worn or damaged components can prevent the spark plugs from firing correctly.
* Fuel System: Issues with fuel injectors, fuel pump, or fuel filter can lead to an inconsistent fuel supply, resulting in misfires.
* Engine Sensors: Various engine sensors (like the crankshaft position sensor or mass airflow sensor) can malfunction and cause the engine computer to misinterpret engine data, leading to misfires.
* Vacuum Leaks: Leaks in the vacuum system can disrupt engine timing and cause misfires.
* Engine Mechanical Issues: Less common, but possible causes include worn valve lifters, low compression in one or more cylinders, or even a damaged piston.
Once you have the trouble codes, you can research the specific code(s) online or consult a repair manual to get a better idea of the problem. However, it's always best to have a mechanic diagnose and repair the issue, especially given the severity indicated by a flashing check engine light. Ignoring the problem could lead to costly repairs down the line.
