[atfdmike]

<H3>hi, Never done it, but does not look too bad. Do not try to unhook fuel rail from fuel supply to do this. Release fuel pressure first as described below. It looks like you should be able to do it.

good luck

2001 Isuzu Truck Trooper S 4WD V6-3.5L

Vehicle Level Engine, Cooling and Exhaust Engine Fuel Pressure Release Service and Repair Service and RepairFuel Pressure Relief Procedure

CAUTION: To reduce the risk of fire and personal injury, there are necessary to relieve the fuel system pressure filler and gauge unit before servicing the fuel system components.

CAUTION: After relieving the system pressure, a small amount of fuel may be released when servicing fuel lines or connections. Reduce the chance of personal injury by covering the fuel line fittings with a shop towel before you disconnect the fittings. The towels will absorb any fuel that may leak out. When the disconnect is completed, place the towel in an approved container.

1. Remove the fuel cap.

1. Remove the fuel pump relay from the underhood relay box.
2. Start the engine and allow it to stall.
3. Crank the engine for 30 seconds.
4. Disconnect the negative battery cable.

</H3>



2001 Isuzu Truck Trooper S 4WD V6-3.5L

Vehicle Level Powertrain Management Fuel Delivery and Air Induction Fuel Pressure Regulator Description and Operation Description and Operation

Fuel Pressure Regulator
The fuel pressure regulator is a diaphragm-operated relief valve mounted on the fuel rail with fuel pump pressure on one side and manifold pressure on the other side. The fuel pressure regulator maintains the fuel pressure available to the injector at three times barometric pressure adjusted for engine load. It may be serviced separate.

If the pressure is too low, poor performance and a DTC P0131, DTC P0151, DTC P0171 or DTC P1171 will be the result. If the pressure is too high, excessive odor and/or a DTC P0132, DTC P0152, DTC P0172 will be the result. Refer to Fuel System Diagnosis for information on diagnosing fuel pressure conditions.


2001 Isuzu Truck Trooper S 4WD V6-3.5L

Vehicle Level Powertrain Management Computers and Control Systems Testing and Inspection Non-Trouble Code Procedures Fuel System Diagnosis Fuel System DiagnosisFuel System Diagnosis

Fuel System Diagnosis
Circuit Description
When the ignition switch is turned "ON", the powertrain control module (PCM) will turn "ON" the in-tank fuel pump. The in-tank fuel pump will remain "ON" as long as the engine is cranking or running and the PCM is receiving 58X crankshaft position pulses. If there are no 58X crankshaft position pulses, the PCM will turn the in-tank fuel pump "OFF" 2 seconds after the ignition switch is turned "ON" or 2 seconds after the engine stops running.
The in-tank fuel pump is an electric pump within an integral reservoir. The in-tank fuel pump supplies fuel through an in-line fuel filter to the fuel rail assembly. The fuel pump is designed to provide fuel at a pressure above the pressure needed by the fuel injectors. A fuel pressure regulator, attached to the fuel rail, keeps the fuel available to the fuel injectors at a regulated pressure. Unused fuel is returned to the fuel tank by a separate fuel return line.

Step 1
Steps 2 - 12
Steps 13 - 23
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart:

1. Connect the fuel pressure gauge to the fuel feed line as shown in the fuel system illustration. Wrap a shop towel around the fuel pressure connection in order to absorb any fuel leakage that may occur when installing the fuel pressure gauge. With the ignition switch "ON" and the fuel pump running, the fuel pressure indicated by the fuel pressure gauge should be 333 - 376 kPa (48 - 55 psi) . This pressure is controlled by the amount of pressure the spring inside the fuel pressure regulator can provide.
2. A fuel system that cannot maintain a constant fuel pressure has a leak in one or more of the following areas:

• • The fuel pump check valve.
  • The fuel pump flex line.
  • The valve or valve seat within the fuel pressure regulator.
  • The fuel injector(s).

1. Fuel pressure that drops off during acceleration, cruise, or hard cornering may case a lean condition. A lean condition can cause a loss of power, surging, or misfire. A lean condition can be diagnosed using a Tech 2. If an extremely lean condition occurs, the oxygen sensor(s) will stop toggling. The oxygen sensor output voltage(s) will drop below 500 mV . Also, the fuel injector pulse width will increase.

IMPORTANT:</B> Make sure the fuel system is not operating in the "Fuel Cut-Off Mode".When the engine is at idle, the manifold pressure is low (high vacuum). This low pressure (high vacuum) is applied to the fuel pressure regulator diaphragm. The low pressure (high vacuum) will offset the pressure being applied to the fuel pressure regulator diaphragm by the spring inside the fuel pressure regulator. When this happens, the result is lower fuel pressure. The fuel pressure at idle will vary slightly as the barometric pressure changes, but the fuel pressure at idle should always be less than the fuel pressure noted in step 2 with the engine "OFF".

1. Check the spark plug associated with a particular fuel injector for fouling or saturation in order to determine if that particular fuel injector is leaking. If checking the spark plug associated with a particular fuel injector for fouling or saturation does not determine that a particular fuel injector is leaking, use the following procedure:

• • Remove the fuel rail, but leave the fuel lines and injectors connected to the fuel rail. Refer to Fuel Rail Assembly in On-Vehicle Service.
  • Lift the fuel rail just enough to leave the fuel injector nozzles in the fuel injector ports.

CAUTION:</B> In order to reduce the risk of fire and personal injury that may result from fuel spraying on the engine, verify that the fuel rail is positioned over the fuel injector ports and verify that the fuel injector retaining clips are intact.

• Pressurize the fuel system by connecting a 10 amp fused jumper between B+ and the fuel pump relay connector.
• Visually and physically inspect the fuel injector nozzles for leaks.

1. A rich condition may result from the fuel pressure being above 376 kPa (55 psi) . A rich condition may cause a DTC P0132 or a DTC P0172 to set. Driveability conditions associated with rich conditions can include hard starting (followed by black smoke) and a strong sulfur smell in the exhaust.

1. This test determines if the high fuel pressure is due to a restricted fuel return line or if the high fuel pressure is due to a faulty fuel pressure regulator.
2. A lean condition may result from fuel pressure below 333 kPa (48 psi) . A lean condition may cause a DTC P0131 or a DTC P0171 to set. Driveability conditions associated with lean conditions can include hard starting (when the engine is cold), hesitation, poor driveability, lack of power, surging , and misfiring.
3. Restricting the fuel return line causes the fuel pressure to rise above the regulated fuel pressure. Command the fuel pump "ON" with the Tech 2. The fuel pressure should rise above 376 kPa (55 psi) as the fuel return line becomes partially closed.

NOTE:</B> Do not allow the fuel pressure to exceed 414 kPa (60 psi) . Fuel pressure in excess of414 kPa (60 psi) may damage the fuel pressure regulator.CAUTION:</B> To reduce the risk of fire and personal injury:

• It is necessary to relieve fuel system pressure before connecting a fuel pressure gauge. Refer to Fuel Pressure Relief Procedure.
• A small amount of fuel may be released when disconnecting the fuel lines. Cover fuel line fittings with a shop towel before disconnecting, to catch any fuel that may leak out. Place the towel in an approved container when the procedure is completed.

Fuel Pressure Relief Procedure

1. Remove the fuel cap.
2. Remove the fuel pump relay from the underhood relay center.
3. Start the engine and allow it to stall.
4. Crank the engine for an additional 3 seconds .

Fuel Gauge Installation

1. Remove the shoulder fitting cap.
2. Install fuel gauge J 34730-1 to the fuel feed line located in front of and above the right side valve train cover.
3. Reinstall the fuel pump relay.