Day 18 - Flash code and Fuel pressure

Flash code

Make: Toyota
Model: 4A-FE

Codes to diagnose the flash codes

Ignition: On, Engine: Off - Check Engine Light lights up

Ignition: On, Engine: On - Check Engine Light should go off, if Check Engine Light remains ON, fault has been detected.

Procedures to extract the codes:

1. Turn the Ignition switch ON

2. Open the diagnostic plug

3. Connect terminals "TE1" and "E1" by using jumper wires

4. Read the fault code

I found the fault code which is "31". By refering to the Codes list, it is described as "Vacuum sensor circuit".

Firstly, I did a visual inspection under the bonnet around MAP sensor. Then I found the MAP sensor has been disconnected. Pluged back in the connector.

To clear the faults codes, EFI fuse has been removed. After one minute, put the EFI fuse back.

When the engine started, Check Engine Light went off. It means there is no fault code.

Fuel Pressure and flow

Make: Toyota

Mode: 4A-FE

Fuel pressure specifications

1. Measure the fuel pressure with the key on, engine off. - 290 kPa

2. Measure the fuel pressure with the engine idling. - 340 kPa

3. With the engine idling, use the special tool to clamp the fuel return line. (NB. this can only be done for a short period) - 500 kPAa

4. With the engine idling, disconnect and plug the vacuum line going to the fuel pressure regulator. - 320 kPa

If the vacuum hose is removed from the fuel pressure regulator when the engine is running, the fuel pressure should increase. If it does not increase, then the fuel pump is not capable of supplying adequate pressure or the fuel pressure is defective. If gasoline is visible in the vacuum hose, the regulator is leaking and should be replaced. Also, when the hose is reattached to the regulator, the fuel pressure should drop.

5. Turn off the engine, and watch the fuel pressure for five minutes. - 300 kPa

Describe the symptons a vehicle would give with each case.

1. Low fuel pressure - Hard cold starts, Garage stalls, Poor cold performance, Hesitation just as the accelerator pedal is depressed
2. Low fuel flow - stalls from time to time while driving
3. High fuel pressure - Run rich, high CO, poor fuel economy
4. Faulty fuel pressure regulator - Stalling, sometimes run rich so high CO