Symptom/Condition, Diagnosis & Parts Information

SYMPTOM/CONDITION

Vapor Lock - Engine performance is gradually reduced in high ambient temperature or high altitude driving due to a drop in fuel pressure, which starves the engine for fuel (goes lean). Engine may not start until fuel system components cool off.

Fuel Foaming - Engine sags and/or exhibits poor performance following a hot soak restart. This condition occurs when cool incoming fuel meets the hot fuel in the carburetor fuel bowl, which creates an over rich condition. Engine will start (unloading technique may be necessary).

DIAGNOSIS

Vapor lock and fuel foaming cause similar conditions. The following are characteristics of each condition and should be observed on a fully warmed up engine. (These conditions do not affect cold engine driveability.)

Vapor Lock

^ Occurs after hot soak, prolonged idle, or highway speeds at any throttle opening.
^ Sag due to lean mixture.
^ No black smoke at tailpipe.
^ Fuel pressure drops to 0.
^ Carburetor air horn dry.
^ No accelerator pump discharge.
^ May not start until engine cools.
^ Engine may not sustain heavy loads.
Fuel Foaming

^ Occurs primarily after hot soak restart or prolonged idle only on medium to heavy acceleration.
^ Sag due to rich fuel mixture.
^ Black smoke at tailpipe.
^ Fuel pressure is normal.
^ Raw fuel at carburetor air horn.
^ Good accelerator pump discharge.
^ Will start immediately (unloading technique may be necessary).

PARTS REQUIRED

1 Fuel Tank & Bi-Metallic Fuel Gauge Package PN 4411990

Refer to parts list for contents of package.

Must be ordered separately:

1 Body Overlay Harness (1981 MY only) PN 4368596
1 Body Overlay Harness (1982 MY only) PN 4368597
1 Authorized Modification Label PN 4275086