Fuel Pressure Switching System
3UR-FBE ENGINE CONTROL SYSTEM: SFI SYSTEM: Fuel Pressure Switching System
- Fuel Pressure Switching System
DESCRIPTION
A Flexible Fuel Vehicle (FFV) is a vehicle with an engine that can be used with a high concentration of ethyl alcohol fuel.
An FFV changes the fuel pressure to a low pressure of 270 to 330 kPa or a high pressure of 370 to 430 kPa using the fuel pressure switching valve.
For example, when starting the engine and during heavy loads while using E85 fuel, the fuel pressure switching valve switches to the high pressure side.
It is necessary to inject more ethanol fuel than gasoline to obtain the same amount of power. Therefore, when a large amount of fuel is required, a high fuel pressure is used.
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE:
Make sure that "Alcohol Density Learning" in the Data List has been completed before performing the following troubleshooting procedures.
When "Alcohol Density Learning" has not been completed, start the engine and drive the vehicle at 32 km/h (20 mph) or more and maintain a constant speed for 2 minutes or more.
HINT
When the DTCs are cleared using the Techstream, the alcohol concentration learned value is also cleared.
The engine is difficult to start if the alcohol concentration of the fuel in the fuel tank is high. Therefore, it may be necessary to crank the engine a few times before it starts.
PROCEDURE
1. CHECK FUEL LEAK
(a) Visually check for fuel leaks.
OK:
No fuel leaks.
HINT
* The fuel pressure is normally 270 to 330 kPa when the fuel pressure switching valve is off, and 370 to 430 kPa when the valve is on.
* If there is a fuel leak, the fuel pressure is below 270 kPa when the fuel pressure switching valve is off, and below 370 kPa when the valve is on.
NG -- REPAIR OR REPLACE FUEL LEAKAGE POINT
OK -- Continue to next step.
2. INSPECT FUEL PRESSURE REGULATOR (for HIGH PRESSURE)
(a) Install the pressure gauge Fuel System.
(b) Start the engine.
(c) Check that the fuel pressure discharge when the ignition switch is turned off.
HINT
If the fuel pressure in the high pressure side pressure regulator cannot remain stable, the fuel pressure changes to below 270 kPa when the fuel pressure switching valve is off, and to below 370 kPa when the fuel pressure switching valve is on.
Result
B -- REPLACE FUEL PRESSURE REGULATOR (for HIGH PRESSURE) Removal
A -- Continue to next step.
3. CHECK FUEL PUMP CONTROL SYSTEM
(a) Check the fuel pump control circuit Component Tests and General Diagnostics.
NOTICE:
Check the fuel pump control circuit and proceed to the next step.
HINT
* The fuel pump ECU changes the fuel pump drive voltage between high, middle, and low. The fuel pump is regulated at a voltage consistent with the fuel consumption amount.
* The fuel pump ECU changes the drive voltage to high when starting the engine and during heavy loads, and low when the engine is idling.
NEXT -- Continue to next step.
4. PERFORM ACTIVE TEST USING TECHSTREAM (FUEL PRESSURE SWITCHING VALVE)
(a) Install the pressure gauge Fuel System.
HINT
In order to reduce the rise in fuel temperature, open the hood during the inspection.
(b) Chock the wheels.
(c) Securely apply the parking brake.
(d) Warm up the engine until the engine coolant temperature is 75°C (167°F) or more.
(e) Connect the Techstream to the DLC3.
(f) Allow the engine to idle and turn the A/C on (MAX COOL, blower motor on maximum setting).
(g) Depress the brake pedal and move the shift lever to D.
HINT
When checking the fuel pressure, it is okay if the shift lever is in N or the air conditioner is off.
(h) Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the Fuel Pressure Switching Valve / All Data / Short FT #1 and Short FT #2.
(i) Using the Active Test, switch the fuel pressure switching valve to "High" and "Low".
(j) Check the change in Short FT and the fuel pressure.
HINT
When performing the Active Test, wait approximately 20 seconds for the Short FT value to stabilize.
Result
HINT
When normal:
Reference values when performing Active Test (E85 Fuel):
When malfunctioning:
B -- REPLACE FUEL SUCTION WITH PUMP AND GAUGE TUBE ASSEMBLY Removal
A -- Continue to next step.
5. CHECK FUEL PRESSURE SWITCHING VALVE (POWER SOURCE)
(a) Disconnect the fuel pressure switching valve connector.
(b) Connect the Techstream to the DLC3.
(c) Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the Fuel Pressure Switching Valve.
(d) Operate the fuel pressure switching valve.
(e) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
NG -- INSPECT RELAY (F/PMP VSV)
OK -- Continue to next step.
6. INSPECT FUEL PRESSURE SWITCHING VALVE
(a) Inspect the fuel pressure switching valve Fuel Pressure Switching Valve.
NG -- REPLACE FUEL PRESSURE SWITCHING VALVE Removal
OK -- REPLACE FUEL SUCTION WITH PUMP AND GAUGE TUBE ASSEMBLY Removal
7. INSPECT RELAY (F/PMP VSV)
(a) Inspect the F/PMP VSV relay Fuel Pressure Control Valve Relay.
NG -- REPLACE RELAY (F/PMP VSV) Fuel Pressure Control Valve Relay
OK -- Continue to next step.
8. CHECK RELAY (F/PMP VSV POWER SOURCE)
(a) Remove the fuel pressure control valve relay (F/PMP VSV) from the engine room relay block.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
NG -- GO TO ECM POWER SOURCE CIRCUIT Component Tests and General Diagnostics
OK -- Continue to next step.
9. CHECK HARNESS AND CONNECTOR (FUEL PRESSURE SWITCHING VALVE - F/PMP RELAY, BODY GROUND)
(a) Disconnect the fuel pressure switching valve connector.
(b) Remove the fuel pressure control valve relay (F/PMP VSV) from the engine room relay block.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE FUEL SUCTION WITH PUMP AND GAUGE TUBE ASSEMBLY Removal