Fuel Pressure
NOTE:
In-tank fuel pump is used. Fuel pump contains internal relief valve and check valve.
- Ensure battery is fully charged and ignition is off. Disconnect negative battery cable.
- Note location of fuel pressure gauge installation. See Fig 1. Place container under delivery pipe or fuel filter. Cover union bolt with shop towel. Slowly loosen union bolt to relieve fuel pressure.
- Remove union bolt and gaskets. Install Fuel Pressure Gauge (SST 09268-45012) using NEW gaskets. See Fig 1. Tighten union bolt. Reconnect negative battery cable.
- Install scan tester on data link connector No. 3. See Figure. Using scan tester manufacturer's instructions, activate electric fuel pump and note fuel pressure. Fuel pressure should be within specification. See FUEL PUMP PERFORMANCE table.NOTE: Fuel pump may also be activated by connecting battery voltage to specified terminals on fuel pump. See Figure.
- If fuel pressure exceeds specification, replace fuel pressure regulator. If fuel pressure is less than specified, check for defective fuel lines, connections, fuel pump, fuel filter, fuel pressure regulator or fuel pressure control Vacuum Switching Valve (VSV) if equipped.
- Remove scan tester from data link connector No. 3. Start engine and allow to idle. Disconnect and plug vacuum line at fuel pressure regulator. Note fuel pressure.
- Reconnect vacuum hose on fuel pressure regulator and note fuel pressure. Fuel pressure should be within specification. See the REGULATED FUEL PRESSURE table.
- If fuel pressure is not within specification, check for defective vacuum hose or fuel pressure regulator. Shut engine off and note fuel pressure.
- Fuel pressure should hold at least 21 psi (1.5 kg/cm2 ) for a minimum of 5 minutes. If fuel pressure does not hold as specified, check for defective fuel pump, fuel injector or fuel pressure regulator.
- Disconnect negative battery cable. Remove fuel pressure gauge. Reinstall union bolt using NEW gaskets. Tighten union bolt. Install negative battery cable.
NOTE:
For more information on checking fuel injectors and other fuel sub-systems, see the SYSTEM/COMPONENT TESTS
article.
FUEL PUMP PERFORMANCE
| Application | psi (kg/cm2 ) |
|---|---|
| 4-Cylinder | 38-44 (2.7-3.1) |
REGULATED FUEL PRESSURE
| Application | At Idle W/Vacuum | At Idle W/O Vacuum |
|---|---|---|
| T100 | 31-37 (2.2-2.6) | 38-44 (2.7-3.1) |