Test 3 & 4 - Fuel Pump Flow/Pressure Tests

FUEL PUMP FLOW/PRESSURE TESTS
These tests will determine whether the fuel system can supply adequate volume of fuel at the desired pressure to operate the engine under full load conditions. The test is done at two points in the system (fuel rail and fuel pump) to isolate and identify the problem component; fuel pump, filter pressure regulator, or fuel supply line.

Description:

TEST 3 - FUEL PUMP REGULATED FLOW/PRESSURE TEST

CAUTION: DO NO 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. Remove air induction tube.
2. Perform Fuel Pressure Release procedure.
3. Remove fuel feed line retainer clip attachment screw (10 mm hex).

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 line at fuel rail.

NOTICE: 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 INLET side of fuel flow/pressure test adapter (SA 9127E-7) into fuel feed line 90 quick connect and make sure fitting is firmly latched.
6. Connect fuel pressure gauge to test adapter.
7. Connect a fuel return hose to quick connect on test adapter and place other end of line into approved container or run return hose back to fuel filler pipe.
8. Turn ON/OFF valve on test adapter to On.

IMPORTANT: Battery must be at a minimum of 12 volts when performing any fuel system tests.

9. Energize fuel pump (refer to "Energizing the Fuel Pump") for a minimum of 10 seconds.
a. Record fuel pressure.
b. Repeat this procedure a minimum of two times.
10. Compare pressure recorded to published specification
11. Refer to "Fuel System Diagnostic Chart" and use test result to make appropriate decision.
System Diagnosis - Fuel System

Description:

TEST 4 - FUEL PUMP FLOW/PRESSURE TEST
For this test the vehicle will be raised on the hoist and as means of controlling the fuel pump from under the vehicle is required. The Scan tool readily provides this function (refer to "Energizine the Fuel Pump" in this manual).

CAUTION: DO NO 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. Perform Fuel Pressure Release procedure (refer to "Relieving Fuel Pressure" in this manual).
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.

NOTICE: 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 (5A9127E-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/Of valve on test adapter to On.
8. Energize fuel pump for a minimum of 10 seconds.
a. Record the fuel pressure.
b. Repeat this procedure a minimum of two times.
9. Using the SCAN tool, determine the hatter voltage (with the pump OFF) and record.
10. Compare pressure and voltage recorded to published specification.
11. Refer to "Fuel System Diagnostic Chart" and use test result to make appropriate decision.
System Diagnosis - Fuel System