1. Fuel System:
* Fuel Pump: A weak or failing fuel pump might provide inconsistent fuel pressure. Listen for the whirring sound of the fuel pump when you turn the key to the "on" position (before cranking). If you don't hear it, or it sounds weak, the pump is a suspect. A fuel pressure gauge test is necessary to confirm.
* Fuel Filter: A clogged fuel filter restricts fuel flow, causing erratic running and stalling. This is a cheap and easy part to replace.
* Fuel Injectors: Clogged or failing injectors can deliver inconsistent fuel, leading to the described symptoms. This requires more advanced diagnostics, often involving a fuel injector cleaning or replacement.
* Fuel Pressure Regulator: A faulty regulator might not maintain proper fuel pressure in the system.
2. Ignition System:
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational speed. A failing CKP sensor can cause erratic running, stalling, and a no-start condition. This is a relatively common failure point in older vehicles.
* Distributor Cap and Rotor: Inspect for cracks, corrosion, or worn contacts. These components distribute the high voltage to the spark plugs. Replacing them is relatively inexpensive.
* Ignition Coil: A failing ignition coil may not provide sufficient spark to all cylinders consistently.
* Spark Plugs and Wires: Worn or fouled spark plugs and damaged wires can prevent proper combustion. Check for gaps, wear, and cracks.
3. Other Potential Issues:
* Throttle Position Sensor (TPS): A faulty TPS provides inaccurate information to the engine control module (ECM) about the throttle position, leading to erratic idle and stalling.
* Mass Airflow Sensor (MAF): A dirty or faulty MAF sensor provides inaccurate readings of air intake, affecting fuel delivery and causing similar symptoms.
* Vacuum Leaks: Leaks in the vacuum lines can disrupt the engine's operation. Inspect all vacuum lines for cracks or disconnections.
* Computer Issues (ECM): While less likely, a faulty ECM can cause erratic behavior. This is typically diagnosed by a professional with a scan tool.
Troubleshooting Steps:
1. Check for Diagnostic Trouble Codes (DTCs): Use an OBD-I scanner (your Suburban uses this older system, not OBD-II) to retrieve any stored trouble codes. These codes can provide valuable clues to the problem's source.
2. Listen for the fuel pump: As mentioned above.
3. Check the basics: Inspect the spark plugs, wires, distributor cap, and rotor.
4. Visual Inspection: Look for any obvious signs of damage, leaks, or loose connections.
5. Start with the easiest and cheapest fixes first: Replace the fuel filter and spark plugs.
6. Professional Diagnosis: If you're not comfortable working on your vehicle, or if the problem persists after checking the basics, take it to a qualified mechanic for diagnosis.
Important Note: Safety first! Always disconnect the negative battery terminal before working on any electrical components. If you're not comfortable working on your vehicle, seek professional help. A misdiagnosed problem could lead to more extensive and costly repairs.
