Quote:
Originally Posted by BigRed76
On the right side of this picture is what I know as a fast idle solenoid. I know that when its plugged in it works, but it never shuts off to allow normal idle. I also noticed that there are two vacuum ports on the side of it that are not connected. Does anyone know how these are supposed to operate? Or is it not worth my time to mess with it?
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It is called a C.E.C. ( Combination Emission Control ) valve and a
complete explaination ( three paragraphs ) of it's function can be found in Section 6T of the 1971 Factory Service Manual.
The lower vacuum port connects to manifold vacuum and the upper port connects to the vacuum advance on the distributor.
One of the electrical connections connects to the water temp. switch which is wired through a 15 second time delay relay and the other connection is wired to the transmission switch and is wired to a reversing relay.
According to the service manual if the C.E.C. does not function it will result in no vacuum advance and no high gear deceleration position of the carb.
Again I urge any one who owns one of these trucks to purchase the factory service manual...it is an invaluable tool to help one figure things out.