W350 1 Ton Pickup 4WD V8-360 5.9L VIN 1 4-bbl (1988)
Technical Service Bulletin # 180788
Date: 880328
Fuel System - Engine Vapor Lock
Models
1988 "D" Trucks With 5.9L-4V Engine
Subject
Correction of Vapor Lock to Improve Engine Performance
Index
DRIVEABILITY
Date
March 28, 1988
No..
18-07-88
P-1122
(C18-08)
NOTE:
CHANGES HAVE BEEN MADE IN THE ENGINE WIRING AND FUEL SYSTEM OF 1988 VEHICLES. PREVIOUS MODEL
YEAR INSTRUCTIONS FOR VAPOR LOCK KITS ARE NOT APPLICABLE.
Symptom, Diagnosis & Parts Information
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 restart until engine cools.
^
Engine may not sustain heavy loads.
PARTS REQUIRED
Order one of the following vapor lock package part numbers:
30 Gallon Fuel Tank
PN 4364385
35 Gallon Fuel Tank (Ramcharger)
PN 4364386
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.
Must be ordered separately:
1
Wiring Assembly - Electric
PN 4362804
Fuel Pump (I/P)
