Firebird V8-305 5.0L VIN F FI (1987)
Engine Control Module: Technical Service Bulletins
ECM , Canister Purge Circuit Diagnosis - Section 6E1
Number 87-6(Gasoline)-69
Date 9/87
Subject:
ECM CONTROLLED CANISTER PURGE CIRCUIT DIAGNOSIS - SECTION 6E1
1987 GRAND PRIX AND FIREBIRD MODELS EQUIPPED WITH A 5.0L LG4 (VIN H) CARBURETED ENGINE
The 1987 subject carbureted engine is equipped with an ECM controlled solenoid that allows vacuum to purge the canister when energized.
Use the information provided with this bulletin for any necessary service needed to functionally check the canister purge system.
CHART C-3CANISTER PURGE SOLENOID CHECK 5.0L (CARB)
Circuit Description:
Canister purge is controlled by a solenoid that allows manifold vacuum to purge the canister when energized. The ECM supplies a ground that is pulse
width modulated (turned "ON" and "OFF" several times a second). The duty cycle (pulse width) is determined by the map sensor input. (Engine
Vacuum) The duty cycle is calculated by the ECM when the following conditions have been met:
^
Engine run time less than specified.
^
Coolant temperature below a given value.
^
Vehicle speed below a given value.
^
TPS below a given value.
