Fuel Fill Cap Check

Check the fuel fill cap (the cap must say "If not tightened 3 clicks check engine light may come on").
Is the correct fuel fill cap installed and properly tightened?
1. YES - Go to step 2.
2. NO - Replace or tighten the cap.
Check the fuel fill cap seal and the fuel fill pipe mating surface.
Is the fuel fill cap seal missing or damaged, or is the fuel fill pipe damaged?
1. YES - Replace the fuel fill cap or the fuel fill pipe.
2. NO - Go to step 3.
1. EVAP Bypass Solenoid Valve Test
Disconnect both vacuum hoses from the EVAP two way valve (A), and connect a vacuum pump to the canister port on the EVAP two way valve.

Fig 1: Disconnecting Vacuum Hoses From EVAP Two Way Valve
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the EVAP bypass solenoid valve ON with the HDS, or connect ECM/PCM connector terminal E20 to body ground with a jumper wire.

Fig 2: Connecting ECM/PCM Connector Terminal E20 To Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch ON (II).
Apply vacuum to the hose.
Does the valve hold vacuum?
1. YES - Go to step 7.
2. NO - Go to step 12.
Turn the ignition switch OFF.
Disconnect the EVAP bypass solenoid valve 2P connector.
Remove the jumper wire from ECM/PCM connector E (31P), and turn the ignition switch ON (II).
Check for continuity between EVAP bypass solenoid valve 2P connector terminal No. 2 and body ground.

Fig 3: Checking Continuity Between EVAP Bypass Solenoid Valve 2-Pin Connector Terminal No. 2 & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Go to step 11.
2. NO - Repair open in the wire between the EVAP bypass solenoid valve and the ECM/PCM (E20).
Measure voltage between EVAP bypass solenoid valve 2P connector terminal No. 1 and body ground.

Fig 4: Measuring Voltage Between EVAP Bypass Solenoid Valve 2-Pin Connector Terminal No. 1 & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 5: Replacing EVAP Two Way/Bypass Solenoid Valves
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Replace the EVAP two way/bypass solenoid valves (A).
2. NO - Repair open in the wire between the EVAP bypass solenoid valve and the No. 4 ACG (10A) fuse.
Plug the fuel tank port (A) of the EVAP two way valve.

Fig 6: Plugging Fuel Tank Port Of EVAP Two Way Valve
Courtesy of AMERICAN HONDA MOTOR CO., INC.
While monitoring FTP sensor voltage with the HDS, or measuring voltage between ECM/PCM connector terminals E4 and E14, slowly pump the vacuum pump once, or until the voltage drops to about 1.5 V.

Fig 7: Measuring Voltage Between ECM/PCM Connector Terminals E4 & E14
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Does the voltage drop to 1.5 V and hold for at least 20 seconds?
1. YES - The EVAP bypass solenoid valve/EVAP two way valve is OK. Go to step 14.
2. NO - Repair the leakage from the EVAP bypass solenoid valve, EVAP two way valve, or FTP sensor.
1. Vacuum Hoses and Connections Test
Perform the fuel tank vapor control valve test (see Fuel Tank Vapor Control Valve Test ).
Is the fuel tank vapor control valve OK?
1. YES - Go to step 15.
2. NO - Replace the fuel tank vapor control valve.
Tighten the fuel cap 3 clicks.
Start the engine, and let it idle for 5 minutes.
Check the FTP sensor readings.

Fig 8: Checking FTP Sensor Readings
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the reading above 0.5 kPa of (4 mmHg, 0.16 in.Hg, 2.8 V) pressure?
1. YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
2. NO - Check the following parts for leaks:
  - Fuel tank (A)
  - Fuel fill cap (B)
  - Fuel fill pipe (C)
  - Fuel tank vapor control valve (D)
  - Fuel tank vapor recirculation valve (E)
  - Fuel tank vapor recirculation tube (F)
  - Fuel tank vapor signal tube (G)
  - Fuel tank vapor control vent tube (H)
  - Two way valve (I)
  - FTP sensor (J)
  - Fuel tank unit base gasket
    Repair or replace any leaking parts.