Fuel System Problems (Most Likely):
* Fuel Pump: This is a high probability. A failing fuel pump might deliver fuel adequately when cold but struggle as the engine warms up or under load. This explains the intermittent nature of the problem. Listen closely near the fuel tank for unusual noises (whining, buzzing) when the engine is running. A fuel pressure test is essential to diagnose a failing pump.
* Clogged Fuel Injectors: Dirty injectors can restrict fuel flow, causing the engine to starve for fuel, especially under load. A fuel injector cleaning or replacement might be necessary.
* Fuel Pressure Regulator: This component regulates the fuel pressure in the system. A faulty regulator could cause inconsistent fuel pressure, leading to the symptoms you're experiencing.
* Pick-up tube in fuel tank: Debris or corrosion in the fuel tank can clog the pick-up tube preventing the pump from pulling sufficient fuel. This is less likely if the problem started recently but is worth consideration if the tank hasn't been serviced.
Other Possibilities:
* Crankshaft Position Sensor (CKP): A faulty CKP sensor can cause the engine to stall or misfire, mimicking fuel starvation symptoms.
* Mass Airflow Sensor (MAF): A dirty or faulty MAF sensor provides inaccurate readings to the engine computer, leading to poor fuel delivery.
* Ignition System Problems: Worn spark plugs, wires, or a failing distributor (if equipped) could cause misfires that mimic fuel starvation symptoms.
* Computer/ECM problems: A faulty Engine Control Module (ECM) could cause various problems, including erratic fuel delivery. This is less likely but possible.
Troubleshooting Steps:
1. Check the OBD-II Codes: Have the service engine light codes read at an auto parts store (many offer this service for free). This will give you a more precise indication of the problem.
2. Fuel Pressure Test: This is CRUCIAL. A mechanic should perform a fuel pressure test to determine if the fuel pump is delivering adequate pressure.
3. Inspect Fuel Lines and Connections: Look for any leaks, cracks, or loose connections in the fuel lines.
4. Check the Fuel Filter (Again): Even though you've changed it, make absolutely sure the new filter is installed correctly and there are no leaks.
5. Inspect and clean MAF sensor (if accessible): Gently clean it with MAF sensor cleaner (following instructions carefully).
Recommendation:
Given the intermittent nature and the fuel starvation symptoms, a fuel pressure test is your best first step. If you're not comfortable performing this yourself, take your Suburban to a qualified mechanic for diagnosis and repair. Ignoring the problem could lead to further damage. Trying to guess and replace parts without diagnosis will be costly and likely won't solve the root cause.
