Fuel System Issues (Beyond the Pump):
* Fuel Filter: A clogged fuel filter can restrict fuel flow, even with a new pump. It's a cheap and easy part to replace.
* Fuel Pressure Regulator: This component regulates fuel pressure within the system. A faulty regulator could cause inconsistent pressure, leading to stalling.
* Fuel Injectors: Clogged or malfunctioning injectors prevent fuel from reaching the engine's cylinders. This often requires specialized testing equipment.
* Wiring/Connections: Problems with the wiring harness to the fuel pump, injectors, or other fuel system components can cause intermittent failures. A mechanic should inspect for corrosion, broken wires, or loose connections.
Ignition System Issues:
* Crankshaft Position Sensor (CKP): This sensor tells the engine's computer where the crankshaft is positioned. A failing CKP can prevent the engine from starting.
* Cam Position Sensor (CMP): Similar to the CKP, but for the camshaft. A faulty CMP can cause similar problems.
* Ignition Coil(s): These components provide the spark to ignite the fuel-air mixture. A failing coil can cause misfires or prevent the engine from starting.
* Spark Plugs/Wires: Worn-out spark plugs or damaged wires can lead to poor ignition and stalling.
Other Possibilities:
* Mass Airflow Sensor (MAF): This sensor measures the amount of air entering the engine. A faulty MAF can cause the engine to run lean or rich, leading to stalling.
* Throttle Position Sensor (TPS): This sensor tells the engine's computer the throttle position. A faulty TPS can cause erratic idle or stalling.
* Computer/ECU Issues: Though less common, a faulty Engine Control Unit (ECU) can cause a wide range of problems, including stalling. This requires specialized diagnostic tools.
* Alternator: While unlikely to directly cause stalling, a failing alternator can leave the battery with insufficient charge, leading to stalling eventually. Have the alternator tested.
* Battery: Though you mentioned it restarting, a weak battery might be the culprit if the initial start is weak. Have the battery load tested.
What you should do:
1. Return to the Mechanic: Explain that the problem persists after the fuel pump replacement. Ask them to specifically test the components listed above.
2. Get a Second Opinion: Take your Suburban to a different reputable mechanic for a second diagnosis. A fresh set of eyes might spot something the first mechanic missed.
3. Provide Detailed Information: When describing the problem, be precise. Note the conditions under which the Suburban stalls (e.g., under load, at idle, after a certain amount of driving), whether there are any warning lights, and any other relevant details.
Don't continue driving the vehicle extensively if it's stalling unpredictably. This could lead to a more serious (and expensive) problem.
