Owner's Problem Description
The owner reports difficulty starting their 2003 Chrysler Town and Country, requiring five cranks to start. They have noticed a shaking idle for some time. After checking the fuel pressure at home, they found no pressure until the engine started. They replaced the fuel pump, suspecting the fuel pressure regulator. However, after installing two new pumps, they still experience no fuel pressure and the vehicle will not start. The owner has checked the fuse and relay, both of which are functioning. They are considering reinstalling the old pump to see if it changes the situation.
Professional Technical Analysis
The 2003 Chrysler Town and Country is equipped with a 3.3L or 3.8L V6 engine and a fuel system that relies on an electric fuel pump located inside the fuel tank. The owner reports a prolonged starting process that requires multiple cranks and shaking idle, indicative of potential fuel delivery issues. After initial testing, the fuel pressure read 0 PSI, prompting the replacement of the fuel pump assembly. Despite replacing it twice with aftermarket pumps, the owner continues to experience no fuel pressure. The fuel system operates under specifications requiring 53-63 PSI at the rail, which is crucial for proper injector function. The connection points for the fuel pump are designed to prevent incorrect installation due to differing sizes, thus eliminating that possibility. Given that the owner has verified the relay and fuse are operational, the next steps should include inspecting the fuel lines for blockages or leaks, verifying that the pump is receiving power during operation, and ensuring the fuel strainer is not clogged. Additionally, the presence of codes P1684 and P0071 suggests that while unrelated to fuel delivery, they indicate a battery disconnect and ambient air temperature sensor issues respectively, which should be documented but are not the primary focus at this time. The vehicle's current inability to start poses safety concerns, particularly if it stalls while in motion.
Possible Causes
Most common causes (ordered by frequency):
- Fuel Pump Failure: The newly installed fuel pumps may be defective or not properly primed, leading to a complete lack of fuel pressure. Aftermarket parts can sometimes have inconsistent quality. The pumps should be tested for power and ground at the connector, ensuring they receive the required voltage (12V) during the key-on position. If the pumps do not activate or show low voltage, further investigation into the wiring and relay is necessary. - No fuel pressure at the rail, new pumps activated but not delivering fuel, checking for 12V power at the pump connector.
- Blocked Fuel Lines or Filter: There could be a blockage in the fuel lines or a clogged fuel filter preventing fuel from reaching the engine. If the fuel pump is operational but no fuel is reaching the engine, checking the lines for kinks or damage and replacing the fuel filter is essential. The fuel filter should be replaced every 30,000 miles as a preventive measure. - No fuel flow from the pump, potential blockage in the line, fuel filter not changed recently.
- Faulty Electrical Connections: Poor connections at the fuel pump connector or issues with the relay could prevent the pump from operating correctly. The relay should be tested to ensure it is functioning (typically should click when the key is turned on) and connections should be free of corrosion. Inspecting the wiring harness for damage is also critical. - Pump not receiving power, relay failure or corroded connections could be involved.
- Fuel Pump Strainer Clogging: If the fuel pump strainer is clogged with debris, it can restrict fuel flow. This is more common in vehicles with low fuel levels and can cause the pump to run dry and fail. The strainer should be inspected for blockages, especially if the vehicle has been running on low fuel frequently. - Possible debris in the tank, poor performance when running low on fuel.
Diagnostic Steps
Professional Diagnosis Process
Follow these systematic steps to accurately diagnose the issue. Each step builds on the previous one to ensure accurate diagnosis.
- STEP 1 - Scan for Diagnostic Codes: Utilize a professional OBD-II scanner or GeekOBD APP to check for any stored codes. The presence of P1684 (battery disconnect) and P0071 (ambient air temperature sensor low) should be noted, but the focus should remain on fuel-related issues. This step will confirm if there are any additional codes that might indicate further underlying problems.
- STEP 2 - Fuel Pressure Testing: Connect a fuel pressure gauge to the fuel rail test port. The acceptable pressure should be between 53-63 PSI when the ignition is turned on. If pressure is zero, the pump may not be delivering fuel or there may be a blockage. Ensure that the gauge is functioning properly and document the readings.
- STEP 3 - Check for Power at the Pump: Using a multimeter, check for voltage at the fuel pump connector. The voltage should be approximately 12V when the ignition is in the ON position. If there is no voltage, check the wiring and relay. If voltage is present but no fuel pressure, the pump may be faulty.
- STEP 4 - Inspect Fuel Lines and Strainer: If the pump is operational but no fuel is delivered, check the fuel lines for kinks, leaks, or clogs. Also, inspect the fuel pump strainer for debris. The strainer should be clean to ensure proper fuel flow.
