4000,S L4-1715cc 1.7L SOHC (WT) (1982)
Fuel Pressure Regulator: Technical Service Bulletins
Control Pressure Regulator - Modification
NO: 81-05
December 22, 1981
Group: 25
5000/S, 5000 TURBO, 4000 (5 cyl.)
1981/1982 CIS cars only
Subject:
Control Pressure Regulator
Part Identifier 25 46
Key Points:
Modified to include an enrichment system
Begining with 1981 models, the control-pressure regulator is modified to include an enrichment system. Operation is as follows:
The modified control-pressure regulator is equipped with chambers I and II, which are separated by a diaphragm. When pressure in the two chambers is
equal, the regulator performs as in the past and no additional enrichment occurs. When pressure is greater in chamber I than in chamber II, control
pressure on the fuel distributor is reduced, enriching the mixture to the engine
Normally Aspirated Engines
When the engine is cold, the temperature switch is closed. Intake manifold pressure is the same at chambers I and II, because the one-way vacuum delay
valve is completely open. On acceleration, however, pressure increases in chamber I more rapidly than in chamber II due to action of the delay valve.
During this delay period, mixture enrichment occurs.
When the engine is warm, the temperature switch is open to atmospheric pressure. On acceleration, reduction in intake manifold vacuum never allows
chamber I to be pressurized greater than chamber II. Thus, no enrichment can occur
Turbocharged Engines