DESCRIPTION
The Early Fuel Evaporation (EFE) system is used on 5.0L and 5.7L carbureted vehicles. EFE system provides heat to engine induction system during cold driveaway, providing rapid engine warm-up. System consists of a butterfly valve and vacuum actuator mounted between the exhaust manifold and the exhaust pipe, a vacuum tube and a coolant activated Thermal Vacuum Switch (TVS).
OPERATION
During cold engine operation, less than 105°F (40°C), manifold vacuum is routed to the EFE vacuum motor through the TVS, closing the EFE butterfly valve. This routes all exhaust gases from that side of the engine through a special crossover passage in the intake manifold, below the carburetor. This results in faster fuel evaporation, more uniform fuel distribution, faster choke opening and reduced emissions.
EFE Vacuum Servo EFE Valve. Scheme 63
QUICK TEST
Note. Before performing EFE quick test, allow engine to cool so that coolant temperature is less than 105°F (40°C)
- Locate EFE valve and note position of actuator arm. On some models, actuator arm may be protected by a metal cover, which must be removed and then replaced after service has been performed.
- Valve should close when engine is started cold. Actuator link will pull into diaphragm housing. If valve closes, go to step 6). If valve does not close, stop engine and remove vacuum hose from EFE valve. Restart engine and check for vacuum at hose. If vacuum is present at hose, go to step 4).
- If vacuum is not present, check vacuum supply to TVS. Repair as necessary. If vacuum is present at TVS and coolant temperature is less than 105°F (40°C), replace TVS. CAUTION: Exhaust manifold will rapidly reach dangerous temperature levels once vehicle is started. Use of heavy gloves is recommended when handling exhaust system components.
- Attempt to move actuator arm by hand. Check for freeness. If valve opens, vacuum motor diaphragm is defective. Replace EFE valve and actuator motor.
- If lever will not move freely, try to free valve using Manifold Valve Lubricant (1050422). Allow time for lubricant to penetrate. If valve cannot be freed, replace valve and actuator motor.
- If valve closed in step 2), allow engine to warm. When coolant temperature exceeds 105°F (40°C), valve should open. if valve does not open, stop engine, remove vacuum hose from EFE valve. Restart engine. If vacuum is still present and coolant temperature is greater than 105°F (40°C), replace TVS.