Question on AFC pump on 98

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CAn someone tell me exactly what advancing the star wheel does to the truck. Just need to know what changes happen when I advance the wheel towards the engine THANKS

 

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Basically theres a throttle limiter on the underside of the afc housing that goes down along the cam plate. This limiter acts as a throttle stop that moves forward with boost pressure. When high boost is present the arm moves out of the way and the rocker arm that the control rack is mounted to rides on the cam plate, also called a full load stop. As the control rack moves forward, more fuel is injected. Adjusting the star wheel toward the motor makes this throttle stop move out of the way with less boost applied to it thus giving full fueling earlier, but at the expense of black smoke. The afc is also called a manifold pressure compensator, it's purpose being to delay max. fueling until the turbo has come up. Adjusting it forward won't increase max power, but taking it away from the motor too much can make it so you never get enough fuel to create the boost needed to move the afc arm to allow max. fuel. The key is to get it adjusted in the happy medium between smoke and responsiveness. Hope this helps. Oh all 12V owners should have the book published by Bosch entitled Diesel Fuel Injection. It gives several good diagrams and explainations of how the pump and governors work.

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2001 3500 QC 4X4 black sport, ETH & everything else except 4. 10s

 

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d90boy,
Where did you get the book? Looks like my type of reading. Been wanting to find out more what goes on with the injector pump. Now if some can find a service manual to show us how to maintain and fix.

 

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I got it from Barnes and Noble, 1-56091-542-0 is the ISBN # for easy ordering. It doesn't tell you how to fix things but it gives a ton of technical data.

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2001 3500 QC 4X4 black sport, ETH & everything else except 4. 10s