Check engine light

Hi,

What codes were found? Did replacement of the solenoids make a difference with shifting? Also, as far as a lean mixture, it could be related to low fuel pressure, a vacuum leak and so on. However, usually it's a vacuum leak. If possible, let me know what code was found to indicate a lean mixture and if you have a live data scanner, let me know the short term fuel trims.

If you don't have a scanner, here is a link that explains how to locate and repair an engine vacuum leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, here is a link that shows in general how to check fuel pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

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Here are the directions specific to your vehicle for testing pressure. The attached pics correlate with the directions and the manufacturer's specs are included in the directions.

2000 Toyota Truck 4 Runner 2WD L4-2.7L (3RZ-FE)
Component Tests and General Diagnostics
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Testing and Inspection Component Tests and General Diagnostics
COMPONENT TESTS AND GENERAL DIAGNOSTICS
FUEL PUMP

ON-VEHICLE INSPECTION

1. CHECK FUEL PUMP OPERATION

pic 1

a. Connect the TOYOTA hand-held tester to the DLC3.
b. Turn the ignition switch ON and TOYOTA hand-held tester main switch ON.

NOTE: Do not start the engine.

c. Select the active test mode on the TOYOTA hand-held tester.
d. Please refer to the TOYOTA hand-held tester operator's manual for further details.

e. If you have no TOYOTA hand-held tester, connect the positive (+) and negative (-) leads from the battery to the fuel pump connector.

pic 2

f. Check that there is pressure in the inlet hose from the fuel filter.

HINT: At this time, you will hear fuel return noise.
If there is no pressure, check these parts:
- M-Fuse (AM2 30A)
- Fuses (EFI 15A, IGN 7.5A)
- EFI main relay
- Fuel pump
- ECM
- Wiring connections

g. Turn the ignition switch to LOCK.
h. Remove the TOYOTA hand-held tester.

pic 3

2. CHECK FUEL PRESSURE
a. Check that the battery positive voltage is above 12 volts.
b. Disconnect the negative (-) terminal cable from the battery.
c. Remove the union bolt and 2 gaskets, and disconnect the fuel inlet pipe from the delivery pipe.

HINT:
- Put a suitable container or shop rag under the delivery pipe.
- Slowly loosen the union bolt.

pic 4

d. Install the fuel inlet pipe and SST (pressure gauge) to the delivery pipe with the 3 gaskets and SST (union bolt).
SST 09268-45014

Torque: 29 Nm (300 kg.cm, 22 ft.lb)

e. Wipe off any splattered gasoline.
f. Connect the TOYOTA hand-held tester to the DLC3. (See step 1.)
g. Reconnect the negative (-) terminal cable to the battery.
h. Turn the ignition switch ON.
i. Measure the fuel pressure.

Fuel pressure: 265 - 304 kPa (2.7 - 3.1 kg/Sq.cm, 38 - 44 psi)

If pressure is high, replace the fuel pressure regulator.
If pressure is low, check these parts:
- Fuel hoses and connections
- Fuel pump
- Fuel filter
- Fuel pressure regulator
- Injectors

j. Disconnect the TOYOTA hand-held tester from the DLC3.
k. Start the engine.
l. Measure the fuel pressure at idle.

Fuel pressure: 206 - 255 kPa (2.1 - 2.6 kg/Sq.cm, 31 - 37 psi)

If pressure is not as specified, check the vacuum sensing hose and fuel pressure regulator.

m. Stop the engine.
n. Check that the fuel pressure remains as specified for 5 minutes after the engine has stopped.

Fuel pressure: 147 kPa (1.5 kg/Sq.cm, 21 psi) or more If pressure is not as specified, check the fuel pump, pressure regulator and/or injector.

o. After checking fuel pressure, disconnect the negative (-) terminal cable from the battery and carefully remove the SST to prevent gasoline from splashing.
SST 09268-45014
p. Reconnect the fuel inlet pipe to the delivery pipe with 2 new gaskets and the union bolt.

Torque: 29 Nm (300 kg.cm, 22 ft.lb)

q. Reconnect the negative (-) terminal cable to the battery.
r. Check for fuel leakage.

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Let me know if this helps and what you find. Also, if you could provide the info I requested, it may help me diagnose possible issues.

Take care,
Joe