Fuel Pressure Switching System [08/2017 - 08/2018]: Procedure

WARNING: This page is about a different car, the 2018 Toyota Sequoia, 2017 Toyota Sequoia, and 2016 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.

CHECK FUEL LEAK
1. 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.
Result:

NG

REPAIR OR REPLACE FUEL LEAKAGE POINT

Result:

OK

See step 2

INSPECT FUEL PRESSURE REGULATOR (for HIGH PRESSURE)

Install the pressure gauge (Refer to PROCEDURE - Step 2 ).
Start the engine.

Check that the fuel pressure discharge when the ignition switch is turned off.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Result	Proceed to
Fuel pressure remains almost constant or discharges gradually after a sudden drop	A
Fuel pressure drops suddenly, and when return hose of the fuel pressure regulator for high pressure is pinched shut, the sudden fuel pressure drop (fuel pressure drops to 270 kPa or less) stops	B

Result:

REPLACE FUEL PRESSURE REGULATOR (for HIGH PRESSURE)

(Refer to REMOVAL [08/2015 - 08/2018] )

Result:

See step 3

CHECK FUEL PUMP CONTROL SYSTEM
1. Check the fuel pump control circuit (Refer to Fuel Pump Control Circuit [08/2017 - 08/2018] ).
  NOTE:
  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.
Result:

NEXT

See step 4

PERFORM ACTIVE TEST USING TECHSTREAM (FUEL PRESSURE SWITCHING VALVE)

Install the pressure gauge (Refer to PROCEDURE - Step 2 ).
HINT:

In order to reduce the rise in fuel temperature, open the hood during the inspection.
Chock the wheels.
Securely apply the parking brake.
Warm up the engine until the engine coolant temperature is 75°C (167°F) or more.
Connect the Techstream to the DLC3.
Allow the engine to idle and turn the A/C on (MAX COOL, blower motor on maximum setting).
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.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the Fuel Pressure Switching Valve / All Data / Short FT B1S1 and Short FT B2S1.
Using the Active Test, switch the fuel pressure switching valve to "High" and "Low".

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

Result	Condition	Proceed to
Short FT change is below 7% and fuel pressure does not change 30 kPa or more	Performing switching between "High" and "Low"	A
Anything except above	Performing switching between "High" and "Low"	B

HINT:

When normal:

Change in Short FT while performing Active Test	10 to 20%
Active Test State	Low	High
Normal Fuel Pressure	270 to 330 kPa	370 to 430 kPa

Reference values when performing Active Test (E85 Fuel):

Data List	Low	High
AFS Voltage B1 S1	3.23 V	3.10 V
AFS Voltage B2 S1	3.26 V	3.05 V
O2S B1 S2	0.11 V	0.33 V
O2S B2 S2	0.13 V	0.21 V
Short FT B1S1	11.7%	-16.5%
Long FT B1S1	-2.4%	-2.4%
Short FT B2S1	11.7%	-16.5%
Long FT B2S1	-2.4%	-2.4%
AF Lambda B1 S1	0.99	0.96
AF Lambda B2 S1	1.00	0.96
Alcohol Density Estimate	73%	73%
Alcohol Density Learning	Compl	Compl

When malfunctioning:

Change in Short FT while performing Active Test	Less than 7%		7% or more
Active Test State	Low	High	Low	High
Fuel pressure when there is fuel leak from fuel pipes	Below 270 kPa	Below 370 kPa	Below 270 kPa	Below 370 kPa
Fuel pressure when fuel pressure in high pressure side pressure regulator cannot remain stable	Below 270 kPa	Below 370 kPa	Below 270 kPa	Below 370 kPa
Fuel pressure when fuel pump ECU is malfunctioning and drive voltage stuck at low	270 to 330 kPa	Below 370 kPa	-	-
Fuel pressure when fuel pump ECU is malfunctioning and drive voltage stuck at high	370 kPa or higher	370 to 430 kPa	-	-
Fuel pressure when fuel pressure switching valve stuck	No change in pressure		-	-
Fuel pressure when fuel pressure in low pressure side pressure regulator cannot remain stable	-	-	Below 270 kPa	370 to 430 kPa
Fuel pressure when fuel pump discharge ability decreases	-	Below 370 kPa	-	Below 370 kPa

HINT:

Perform "Inspection After Repair" after replacing the fuel pump (Refer to INITIALIZATION [08/2017 - 08/2018] ).

Result:

REPLACE FUEL SUCTION WITH PUMP AND GAUGE TUBE ASSEMBLY

(Refer to REMOVAL [10/2016 - 08/2018] )

Result:

See step 5

CHECK FUEL PRESSURE SWITCHING VALVE (POWER SOURCE)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Disconnect the fuel pressure switching valve connector.
Connect the Techstream to the DLC3.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the Fuel Pressure Switching Valve.
Operate the fuel pressure switching valve.

Measure the voltage according to the value(s) in the table below.

Standard Voltage

Tester Connection	Condition	Specified Condition
R8-1 - R8-2	High selected in Active Test	11 to 14 V

Result:

See step 7

Result:

See step 6

INSPECT FUEL PRESSURE SWITCHING VALVE
1. Inspect the fuel pressure switching valve (Refer to INSPECTION [08/2015 - 08/2018] ).
  HINT:
  
  Perform "Inspection After Repair" after replacing the fuel pump (Refer to INITIALIZATION [08/2017 - 08/2018] ).
Result:

OK

REPLACE FUEL SUCTION WITH PUMP AND GAUGE TUBE ASSEMBLY

(Refer to REMOVAL [10/2016 - 08/2018] )

Result:

NG

REPLACE FUEL PRESSURE SWITCHING VALVE

(Refer to REMOVAL [08/2015 - 08/2018] )
INSPECT RELAY (FPCV VSV)
1. Inspect the FPCV VSV relay (Refer to PROCEDURE - Step 6 ).
Result:

NG

REPLACE RELAY (F/PMP VSV)

Result:

OK

See step 8

CHECK RELAY (FPCV VSV POWER SOURCE)

Remove the fuel pressure control valve relay (FPCV VSV) from the engine room relay block.
Turn the ignition switch to ON.

Measure the voltage according to the value(s) in the table below.

Standard Voltage

Tester Connection	Condition	Specified Condition
FPCV VSV relay (5) - Body ground	Ignition switch ON	11 to 14 V

Result:

GO TO ECM POWER SOURCE CIRCUIT

(Refer to ECM Power Source Circuit [08/2017 - 08/2018] )

Result:

See step 9

CHECK HARNESS AND CONNECTOR (FUEL PRESSURE SWITCHING VALVE - FPCV RELAY, BODY GROUND)

Disconnect the fuel pressure switching valve connector.
Remove the fuel pressure control valve relay (FPCV VSV) from the engine room relay block.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
Q8-1 - FPCV VSV relay (3)	Always	Below 1 Ω
Q8-2 - Body ground	Always	Below 1 Ω
Q8-1 or FPCV VSV relay (3) - Body ground	Always	10 kΩ or higher

HINT:

Perform "Inspection After Repair" after replacing the fuel pump (Refer to INITIALIZATION [08/2017 - 08/2018] ).

Result:

REPLACE FUEL SUCTION WITH PUMP AND GAUGE TUBE ASSEMBLY

(Refer to REMOVAL [10/2016 - 08/2018] )

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR