* Fuel Pump: This is the primary suspect. A failing fuel pump might deliver fuel intermittently, especially when the tank is low or the pump is getting hot. It may struggle to build sufficient pressure to reach the injectors. Listen carefully near the fuel tank while someone cranks the engine – you should hear a whirring sound from the pump. If it's weak or absent, it's highly likely the pump is failing.
* Fuel Pump Relay: The fuel pump relay is an electrical switch that turns the pump on and off. A faulty relay can cause the pump to not activate even though it's functional. These are inexpensive to replace.
* Clogged Fuel Filter: A clogged fuel filter restricts fuel flow. This is more likely to cause a consistent problem, but could manifest as intermittent issues depending on the level of clogging and the engine's demands.
* Fuel Pressure Regulator: This regulates fuel pressure within the system. A faulty regulator could lead to inconsistent pressure, resulting in intermittent starting.
* Wiring Issues: Corrosion, damaged wires, or loose connections in the fuel pump circuit can disrupt the power supply to the pump. Inspect the wiring harness and connectors for any signs of damage.
* Pick-up Tube in Fuel Tank (Rare, but possible): The pick-up tube in the fuel tank draws fuel from the bottom. If it's clogged or damaged, it could prevent fuel from reaching the pump, especially when the tank is low.
* Inertia Switch (sometimes called Crash Switch): This safety device cuts the fuel supply in a collision. If it's tripped accidentally, it could need resetting (usually a small button on the switch).
Troubleshooting Steps:
1. Check the fuel level: Ensure the fuel tank isn't nearly empty. A low fuel level can exacerbate existing fuel delivery problems.
2. Listen for the fuel pump: As mentioned above, listen for the pump's whirring sound during cranking.
3. Check the fuel pressure: This requires a fuel pressure gauge. This is the most definitive way to determine if you have sufficient fuel pressure. You'll need a pressure gauge and a fitting to connect it to a fuel line. Consult a repair manual for your specific Suburban model to determine the correct pressure and testing procedure.
4. Inspect the fuel filter: Visually inspect the fuel filter for any signs of damage or excessive dirt. A replacement is relatively inexpensive.
5. Check the fuel pump relay: Locate the fuel pump relay (consult a repair manual or online resources) and visually inspect it for damage or corrosion. You can often swap it with another relay of the same amperage rating to see if that resolves the issue.
6. Inspect wiring: Check all wiring related to the fuel pump, including connectors at the pump and relay.
If you're not comfortable working on your fuel system, it's best to take your Suburban to a qualified mechanic. Working with fuel systems involves potential fire hazards, so safety should be your top priority. Remember to always disconnect the battery's negative terminal before working on the fuel system.
