Engine - Poor Cold Driveaway Performance When Cold
84chevy05Number: 84-178
Section: 6E (VIt)
Date: Sept., 1984
Subject: COLD DRIVEABILITY DIAGNOSIS
Model and Year: 1984 10-30 "C/K/G/P" MODELS
TO: ALL CHEVROLET DEALERS
This cancels and replaces 84-178 dated August, 1984 which should be destroyed. This copy identifies applicable vehicle applications.
VIN
Emission Engine
Model Engine System Code
Pickup, Van,
Suburban, and Blazer 5.0L V8 Federal H
Pickup, Van,
Suburban, Step Van,
and Chassis Cab 5.7L V8 California M
Pickup, Suburban,
and Motor Home 7.4L V8 California W
Some 1984 trucks, as listed above, may exhibit poor driveaway and performance when cold. When diagnosing cold driveability and performance comments, refer to the Shop manual Driveability and Emissions Diagnosis Section. If the condition cannot by resolved by normal diagnostic procedures, check the EFE (Early Fuel Evaporation) valve for proper operation (Chart C-9C).
After starting the cold engine, observe the EFE valve. If the EFE valve does not close, follow the diagnostic procedure shown on Chart C-9C. If the condition is not corrected, the following revision should be performed.
EFE check valve:
1. Remove the EFE check valve from the vacuum supply line as shown.
2. Reconnect the vacuum supply line by inserting a straight hose connector, P/N 560625.