Using Scan Tools for Fast Fuel Pump Diagnostics

Diagnosing fuel pump issues in late-model cars can be fraught with wild goose chases, errors and other pitfalls. One simple way to avoid a misdiagnosis is by employing the use of a scan tool.

When working on late-model vehicles, it’s typically quicker and easier to diagnose a fuel pump issue with a scan tool that has applicable data stream displays and bi-directional controls. With these kinds of features, a technician can rapidly evaluate a fuel pump’s electrical status and current performance by using the scanning tool to actually activate the pump.

Anti-Theft Disabling

In some cases, a fuel pump’s circuit may be temporarily disabled if the anti-theft system of a vehicle detects a defective or unauthorized key in the ignition switch. The scan tool may also be used for downloading trouble codes and data indicators if a car’s security system (or any other vehicle subsystem) has temporarily disabled the fuel pump as part of an anti-theft strategy.

Powertrain Control Module (PCM)

A scan tool also comes in handy when diagnosing a pulse-modulated fuel pump system. Because pulse-modulated systems are a complex story in and of themselves, it would be tough to illustrate and explain them thoroughly in this context. However, the Powertrain Control Module (PCM) tailors and regulates fuel pump pressure.  It does this in order to meet a variety of operating conditions by controlling the fuel pump speed and pulsing an electrical current into the pump. If the pulse width requirements ever exceed normal parameters, the PCM has a fuel pump diagnostic trouble code stored within it that will appear during the scan.

Fuel Pump Electrical Issues

If power is available at the vehicle’s fuel pump, the technician should inspect the fuel tank electrical connector to see whether it is loose or has any burnt connector pins. Connectors burned by an excessive amperage draw as a result of a defective fuel pump very often cause multiple fuel pump failures. If the pump’s circuit is grounded to the frame, you can perform preventive maintenance to the system. This is done by cleaning the connector and frame and then applying an anti-corrosion compound directly to the connection.

Primary Causes of Improper Fuel Pump Operation and Failure

• Corrosion, rust, buildup or other types of contamination within the vehicle fuel tank
• Faulty fuel pump connectors or wiring
• Plugged or clogged strainers and/or fuel filters

A scan tool aids in facilitating the accurate diagnosis of fuel pump problems so that they can be correctly resolved.