5C - Fuel System LEAKDOWN Test (Fuel Pressure Regulator)

TOOLS REQUIRED

SA9127E-7 Fuel Flow/Pressure Adapter

Fig 1: Connecting Fuel Flow/Pressure Adapter

Courtesy of GENERAL MOTORS CORP.

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.

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.

Relieve fuel system pressure. Refer to FUEL SYSTEM PRESSURE RELIEF .
Disconnect fuel return line from fuel rail.
Connect Fuel Flow/Pressure Adapter SA9127E-7 inlet to fuel rail return side and outlet to front fuel return line.
1. Close valve on outlet side of tool.
2. Connect pressure gauge to fuel flow/pressure adapter.
IMPORTANT: Battery must be at a minimum of 12 volts when performing any fuel system tests. Charge battery before proceeding if below 12 volts.
Energize fuel pump for a minimum of 10 seconds. (Refer to ENERGIZING THE FUEL PUMP ).
1. Record fuel pressure.
2. Shut fuel pump Off.
3. Wait five minutes.
Fig 2: Connecting Fuel Flow/Pressure Adapter To Test Fuel Pressure Regulator
Courtesy of GENERAL MOTORS CORP.
Record fuel pressure and subtract from pressure recorded in previous step. (Repeat this procedure a minimum of two times.)
Compare pressure loss (decay) to specification.

Fig 3: Fuel System Leakdown Test Specification
Courtesy of GENERAL MOTORS CORP.
Refer to FUEL SYSTEM DIAGNOSIS - FUEL SUPPLY CHART and use test result to make appropriate decision.