i pulled my afc apart, pulled the pin and diafram out. noted all stock locations. turned pin so deepest slope was on rack. re assembled. result- loss of power. seems as if the boost doesnt get high enough to cycle diafram, thus not working the rack. if you tromp the throttle it acts as if it has a choked filter. but ran like a top(or stock first gen) when i pulled her in the shop. any imput appreciated!

 

Sounds like the main fuel screw needs to be adjusted

 

main fuel as in the smoke screw? or the power adj. screw?

 

As you stated, the pin travels based on boost reference. Make sure the reference line going into the pump top has both the copper washers on it. You might have a boost leak. Did you remove the afc spring also? Because that can also cause the rack to stick.

 

no boost leaks from what i can tell. the rack seems as if it set in the closed position from removing the pin, and will not pop back out. is there a spring set on the rack to make it move? the spring is still in the afc.

 

Sometimes the pin will stick in its bore. Pull the top and see if the pin in free, if not try some penatrating oil a see if it will free up. With the engine off the pin should move out when you open the throttle and be free to slide back in with the throttle closed.When you pulled the fuel pin it forced it into its hole farther than it would normally travel. Rocky

 

Pull your pin. Put some heavy grease on the face of it. Reinsert with deepest part facing the front the truck. Take truck out and run the hell out of it. Pull pin and note the witness mark you just made on the pin. IS it all the way to the deepest part?

I'm guessing boost leak. You did nothing else to loose power. Most likely lost one of the two copper washers on the ref line.

 

no boost leak. i do have the pin in the correct position. i adjusted the power screw(behind and under) the boost supply line. i got my throttle response and some power back but now my idle and full throttle is jacked up... this thing just keeps me guessing

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and i wouldnt have been able to grease the pin and run the hell out of it. it would barely gain RPM's

 

one you shouldn't have turned on the fuel screw until you figured out the other problem first. (ONE THING AT A TIME) you have to adjust idle after adjusting is done on the fuel screw.

 

By greesing the pin and running it we can tell of the AFC is working. You should not have messed with your full power screw, put it back till we find your problem. How do you know you don't have a boost leak. Also while the pin is out look in the AFC and hit the throttle. You should see the pin for the rack come out. Push it back in with a screw driver before putting your pin back in.

Did you do anything else to the truck before the problem? Just messing up a AFC adjustment should not make it run as bad as your saying.