Fuel System - Vapor Lock: Overview

85chrysler11

Models


1981-1985 Van & Wagon Models Equipped With 5.2L or 5.9L Engine


Subject


Vapor Lock


Index


DRIVEABILITY


Date

December 20, 1985

No.

18-19-85 REVISION A


P-4782-C

This bulletin supersedes Technical Service Bulletin #18-19-85 which should be removed from your files. The model application has been expanded to include 1981 and 1982 model years.

SYMPTOM/CONDITION

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

DIAGNOSIS

The following are characteristics of vapor lock and should be observed on a fully warmed up engine. (Vapor lock does not affect cold engine driveability.)

^ 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.

PARTS REQUIRED

ORDER ONE OF THE FOLLOWING TWO PART NUMBERS:

Vapor Lock Package With 22 Gallon Fuel Tank PN 4397611
Vapor Lock Package With 36 Gallon Fuel Tank PN 4397612

ADDITIONAL PARTS INFORMATION ON NEXT PAGE
1981-1984 models equipped with Carter Thermoquad 4BBL carburetor must order the following package in addition to the vapor lock package.

Fuel Pressure Regulator Package PN 4397639

All vehicles equipped with dual air conditioning, without electrically heated rear window defroster, and with 60 amp alternator must order the following package in addition to the vapor lock package.

If vehicle is equipped with a 114 amp alternator, do not order this package or make any changes to the charging system.

1 78 AMP Alternator Package PN 4397615

Refer to parts list for contents of each package.

Must be ordered separately:

1 Authorized Modification Label PN 4275086

NOTE: IT IS IMPORTANT THAT THE SPECIFIED FUEL TANK SIZE
APPLICATION PACKAGE BE SELECTED. THE USE OF AN IMPROPER PART NUMBER PACKAGE MAY CAUSE THE VEHICLE TO RUN OUT OF FUEL WELL BEFORE THE GAUGE READS EMPTY.

REPAIR PROCEDURE