4 - Fuel Pump Flow/Pressure Test
TOOLS REQUIRED^ SA9127E-7 Fuel Flow/Pressure Test Adapter
For this test, the vehicle will be raised on the hoist and a means of controlling the fuel pump from under the vehicle is required. The Scan tool readily provides this function (refer to "Energizing the Fuel Pump").
CAUTION: DO NOT ALLOW SMOKING OR THE USE OF OPEN FLAMES IN THE AREA WHERE WORK ON THE FUEL SYSTEM IS TAKING PLACE ANYTIME WORK IS BEING DONE ON THE FUEL SYSTEM, DISCONNECT THE NEGATIVE BATTERY CABLE, EXCEPT FOR THOSE TESTS WHERE BATTERY VOLTAGE IS REQUIRED
IMPORTANT: Battery must be at a minimum of 12 volts when performing any fuel system test. Charge battery before proceeding if below 12 volts.
1. Connect Scan tool to vehicle and turn Ignition to On.
2. Relieve fuel system pressure (refer to "Relieving Fuel Pressure").
3. Raise vehicle to comfortable working position.
CAUTION: WHENEVER FUEL LINE FITTINGS ARE LOOSENED OR REMOVED, WRAP A SHOP CLOTH AROUND THE FITTING AND HAVE AN APPROVED CONTAINER AVAILABLE TO COLLECT ANY FUEL.
4. Disconnect fuel feed (5/16 in.) and fuel return (3/8 in.) lines at fuel filter/pressure regulator.
NOTE: To properly utilize the fuel flow/pressure test adapter it must always be connected with the fuel feed line on the "INLET" side of the adapter and the fuel return or drain line connected to the side with the flow control (ON/OFF) valve. If not connected properly, a "zero" pressure reading will always be read. Use the appropriately sized connector fittings to hookup the adapter to the feed and return lines.
5. Connect Fuel Flow/Pressure Test Adapter SA9127E-7 to (1) feed and (2) return lines and make sure connections are firmly latched.
6. Connect fuel pressure gauge to test adapter.
7. Turn ON/OFF valve on test adapter to On.
8. Energize fuel pump for a minimum of 10 seconds.
8.1 Record the fuel pressure, while pump is energized
8.2 Repeat this procedure a minimum of two times.
9. Using the SCAN tool, determine the battery voltage (with the pump OFF) and record.
10. Compare pressure and voltage recorded to published specification.
11. Refer to "Fuel System Diagnosis Fuel Supply Chart" and use test result to make appropriate decision.