Vacuum Hoses and Connections Test

30. 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 31.
2. NO - Replace the fuel tank vapor control valve.
31. Tighten the fuel cap three "clicks", then monitor the FTP readings with the HDS.
32. Start the engine, and let it idle for 5 minutes.
33. Check the FTP sensor reading.

Fig 1: Checking FTP Sensor
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the reading above 4 mmHg pressure or below - 4 mmHg vacuum?
1. YES - Substitute a known-good ECM (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES ) and retest. If the symptom/indication goes away, replace the original ECM (see ECM REPLACEMENT ).
2. NO - Check these parts for vacuum 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)
  - Repair or replace parts as needed.