Electrical Issues:
* Blown Fuse or Relay: The fuel pump is controlled by a fuse and a relay. A blown fuse or a faulty relay will prevent power from reaching the pump. This is the most common and easiest to check first.
* Wiring Problems: Worn, corroded, or damaged wiring between the fuel pump, relay, and fuse can interrupt the power supply. This often happens due to age, rodents, or physical damage. Check the wiring harness for breaks, chafing, or corrosion.
* Fuel Pump Relay Switch: The relay itself might have failed internally. A simple swap with a known good relay (same amperage rating) can quickly diagnose this.
* Inertia Switch: Some Dodge Rams have an inertia switch (a safety device that cuts power to the fuel pump in a collision) which might have tripped. Locate and reset this switch if it's present.
* Computer Issues (PCM): While less likely, a malfunctioning Powertrain Control Module (PCM) could be sending the wrong signals or no signal to the fuel pump. This requires more advanced diagnostics.
* Low Voltage: Insufficient voltage from the battery or alternator can prevent the fuel pump from running. Check your battery voltage and alternator output.
Mechanical Issues:
* Pump Motor Failure: The pump motor itself could have burned out due to age, overheating, or debris in the fuel tank. This is a common cause of failure.
* Pump Wear and Tear: The pump's internal components (diaphragms, brushes, etc.) can wear out over time, reducing its ability to pump fuel effectively or stopping it altogether.
* Fuel Filter Clogging: A clogged fuel filter restricts fuel flow, potentially causing the pump to overheat and fail. Replacing the fuel filter is a relatively inexpensive maintenance item and should be done regularly.
* Debris in the Tank: Rust, sediment, or other debris in the fuel tank can damage or block the fuel pump. A dirty fuel tank might require cleaning or replacement.
* Pump Seal Failure: A leak in the pump's seal can cause a loss of pressure and ultimately lead to pump failure.
Troubleshooting Steps:
1. Check the fuses and relays: This is the easiest and quickest first step.
2. Inspect the wiring: Look for any damage, corrosion, or loose connections in the wiring harness leading to the fuel pump.
3. Check the fuel filter: Replace it if it's dirty or clogged.
4. Listen for the fuel pump: When you turn the ignition key to the "on" position (but don't start the engine), you should hear a brief hum from the fuel pump. If you don't hear it, the pump itself or its power supply is likely the problem.
5. Test the fuel pump relay and inertia switch (if applicable).
6. Check the battery voltage and alternator output.
If these steps don't pinpoint the issue, further diagnosis may require specialized tools and knowledge. A mechanic with experience working on Dodge Rams can perform a more in-depth check, including testing the fuel pump directly and checking the PCM for fault codes.
