Energizing The Fuel Pump

All of the fuel system tests will require operation of the fuel pump to measure pressure, evaluate pressure decay, or perform the pressure at calibrated flow tests.

Although the fuel pump can be controlled with the ignition, this is fairly awkward for the following reasons:

• The pump is only energized for 2-3 seconds at Key On (and then a wait of 10 seconds is required after Key Off before the pump can be powered again).
• Some of the tests are run with the vehicle on the hoist with control of the pump under the car required.
• The pressure at flow tests require the pump to run for 10-20 seconds.

The Scan tool provides control of the fuel pump at the technician's finger-tips. The tool will run the pump for one minute after the On command. This timer will then shut the pump Off.