Join Date: Jan 2006
Thanked 38 Times in 11 Posts
iTrader Score: 0 reviews
put simply, the AFC (aneroid fuel control) is there to handle fueling levels under no boost conditions. The pump has no sensory circuits to know emmisions and/or engine operating parameters. All it kows, is how to set the fuel rack for a given throttle demand, and to limit the top-end rpm of the engine. That's it. So the Aneroid takes this a step farther by sensing manifold pressure to cut back on fuel until MAP is present, at which time it pulls off and allows normal pump operation.
The governor arm contacts the "torque plate" only in high engine load, high demand situations. Most of the time the arm will not swing out and ride the plate....it is only there to limit rack travel in high power request conditions. Again, the pump is stupid, it will supply X amount of fuel for X amount of throttle angle. Without the torque plate there to tailor that fuel delivery, less than optimum fuel delivery is a result. Just like adjusting the ECM fueling maps in a gas engine, except this pump does it mechanically, with a profile and a follower, and the only adjustment you have is to curve your own plate, other than the cursory forward/backward movement. Now you know whay they call it a stupid pump. Doesn't even dynamicly time the engine either, which leaves a lot of decisions whether to static time it for power or streetability...cuz it's constant throughout the rpm range.