Section 03-13: Evaporative Emissions
1994 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Pinpoint Tests

  

PINPOINT TEST A: ABNORMAL FUEL TANK PRESSURE

 

A1 CANISTER HOSE AND INLET TUBE BLOCKAGE TEST

Yes
GO to A2.

No
GO to A6.

 

A2 FUEL EVAPORATIVE EMISSION SYSTEM BLOCKAGE TEST

Yes
REMOVE blockage or REPLACE component.

No
GO to A7.

 

A3 VAPOR TUBE INSPECTION

  • Inspect vapor tube and fuel vapor hoses for kinks or pinched areas.
  • Are tube or fuel vapor hoses kinked or pinched?
Yes
SERVICE or REPLACE tube or fuel vapor hoses. VERIFY service.

No
GO to A4.

 

A4 VAPOR HOSE INSPECTION

  • Inspect vapor hose routing between fuel tank and body for pinch.
  • Is vapor hose pinched?
Yes
LOOSEN fuel tank and reroute hose. VERIFY service.

No
GO to A5.

 

A5 FUEL VAPOR VALVE INSPECTION

  • Remove fuel tank .
  • Remove fuel vapor valve .
  • Inspect fuel vapor valve for open air passage through orifice.
  • Is air passage open?
Yes
INSTALL fuel vapor valve in fuel tank . INSTALL fuel tank . System test complete.

No
REPLACE fuel vapor valve . VERIFY service.

 

A6 FLOW TEST (FUEL TANK FILLER CAP INSTALLED)

 CAUTION: Do not use other high pressure air supplies. Will result in damage to fuel vapor canister .

  • Install hand pump and pressure gauge Rotunda 021-00014 Vacuum and Pressure Tester or equivalent in fuel vapor hose at test point B1.
  • Hand pump to a maximum of 17.2 kPa (2.5 psi).
  • Does pressure drop to zero immediately?
Yes
System flow OK, no service required.

No
PERFORM Pinpoint Test Step A3.

 

A7 FLOW TEST (FUEL TANK FILLER CAP REMOVED)

 CAUTION: Failure to remove fuel tank filler cap may result in damage to fuel tank .

  • Remove fuel tank filler cap from fuel tank filler pipe .

     CAUTION: Do not use other high-pressure air supplies. Damage to fuel tank may result.

  • Install hand pump and pressure gauge onto tee or fuel vapor canister nipple at test point B2.
  • Hand pump to a maximum of 17.2 kPa (2.5 psi).
  • Does pressure drop to zero immediately?




Yes
System OK, no service required.

No
PERFORM Pinpoint Test Step A4.