Quote:
Originally Posted by lostmarbles
Well the air-intake butterfly would still have some control over the engine rpm - but only through varying the engine's air supply.
The fuel would never move away from the "maximum pedal-to-the-floor" setting.
(Very smokey I would imagine and it certainly wouldn't idle smoothly or at the normal revvs.)
 |
Hey, just reviewed this thread and while I don't have a diesel with the diaphram, I think I have something to contribute in the area of the hoses.
If you look closely at the profile of the throttle body, you should see that the tubes connect to the venturi at different heights.
Given the different configurations of our motors, this may explain the "crossed" and "uncrossed" hoses. Some throttle bodies may have different locations for the placement of the taps or just mounted to the manifold in a reversed position. By understanding why the hoses connect at different heights, guesswork is eliminated.
The different heights will give you indication of what tube goes where. Someone with a few minutes and who cares to do so can confirm this:
The tube that intersects the venturi lbelow the butterfly in the venturi will be your diaphram "signal" that increases and decreases vacuum offsetting the spring. This is because as the butterfly opens and closes, the available vacuum in the venturi rises and falls. NOTE: Look closely at the construction of the throttle body. There may be an internal difference of the outside hose connections and the actual position of the opening inside the throttle body.
From what I have read from your posts the spring pushes the diaphram rod towards rich, so the lower venturi "signal" hose should connect to the diaphram housing on the same side of the spring on the diaphram. Vacuum on the diaphram at idle pulls the diaphram and rod back against the spring, lowering the fuel supply.
The higher venturi hose connection is to equalize pressure on the diaphram in accordance with the presures in the intake above the butterfly. The net effect intended is to create a stable relationship across the diaphram that is solely affected by the throttle butterfly. This upper venturi hose is connected opposite to the spring side of the diaphram.
Feel free to confirm or prove otherwise and post your findings.
Rick