'83 F100, 302. I've owned for a few months. Ran terrible when I bought it and the AOD seemed like it was slipping and shifting irratic and/or hard. I've changed the tranny fluid and cured many problems with a tune up and finding vac leaks. The main problem now is no fast idle.

Choke is working fine. What I did find tho... was a plastic piece on the rod connecting the choke butterfly to the choke coil assembly. The plactic piece has an adjustment screw, but the whole piece is loose - it doesn't adjust anything. It also appears like maybe there was a rod hooked to it? This plastic piece looks like it is broken and if there was another part or rod - it is gone.

There is also a tube from the tail end of the exhaust manifold that goed to the back of the carb. It is rusted and broken off at the manifold. Looks like this is prob a common occurance by the design. What is this for?

Thanks!

 

That sounds like the choke heat pipe, delivering warm air to the choke housing, right?

Fast idle: Can you manually put it on (engine off) by closing the choke butterfly and rotating the throttle. The fast idle cam should be there and rotate, so when you release the throttle, the little screw rests on the fast idle cam.

 

I looked at another truck that has the same setup - The plastic piece was broke and there is a rod that connects to it. It looks like the rod goes down from this plastic piece to control the butterfly. I'm thinking I need to get that replaced first. Maybe this IS really a choke issue.

There is another pipe that goes to the choke. The one in question goes into the back of the carb, up on top and allows warm air into the carb - I had someone else suggest that maybe this was there to keep the carb de-iced.

 

The pipe your talking about relates to the temp of the choke, without it...it would not know if the engine is warm or is still cold. Its supposed to have a fitting someplace on the exhaust that connects to the choke housing. Inside the choke housing is a round like device (don't remember what the name is...)that contracts and expands when heat is around it, WHEN the engine is warm, it expands in a circle like postion that moves a lever forward which is connected to the butterfly tab linkage inside the carb...as the engine warms up, it moves it to open the butterfly (the valve you see when you look down inside the carb. Which at the time that the engine is warm, the butterfly is fully open allowing the motor to run correctly.
To adjust it, those screws you see on the side, of the choke housing, controls everything pertaining to the choke setting, When the engine is completely cold, I think the top screw adjusts the butteryfly to almost close, after the engine is warm, the steps allow the butterfly to drop off the cam and allowing the engine to run properly. Check the haynes, or your manual for the correct way to make the adjustsment, every engine that has an automatic choke an carb will have this setup, and there are different ways to adjust it. A EFI engine will not have this kind of a setup, through the sensors is the way the engine knows whats setting the engine will run better.

 

Okay LocknKey, you're evidently the guru here and you were most helpful yesterday. Today I replaced the power valve in the Carb (it had a pinhole in it - imagine that) so now that has been replaced. The plate the EGR bolts into has been completely cleaned in ChemDip and is almost new in appearance, the hoses that were brittly while removing all of this were replaced with new ones and I skipped the whole nightmare of cleaning the EGR and bought a new one. On a test run, it races at stop lights, and has NO acceleration. I can get up to 3rd and then it's 0-60 if it feels like it. It will not do above 60. So what did I do here? I had to stop at this point after an entire day of chasing down parts and buying rebuild kits and cleaning crap I am a heartbeat away from bashing in the windows with a sledgehammer. Now, I just want it to run correctly. At this point we are talking about new engine, newly rebuilt carb, New EGR, full new vacuum lines, new pcv valve. Are the screws on the side of the carb to blame for all of this? Is it the choke?

 

Just a thought Percy..why not try cleaning the old EGR, remove the carbon deposits and reinstall it...the reason being is because on some engines the EGR has to be the same nomenclature (part number) as the old one, some times auto part sales people will give you the wrong EGR because of the close fit (same design, but different vaccum pressure diaphram) Even egr gaskets can leak...

On another note, did you install the power valve correctly? Do you hear any hissing while it idleing? Have you checked to see if everything that you replaced is done right?

While its fustrating trying to figure this out while on a keyboard, something there isn't right someplace...

 

Your mechanic was the one that said it was the power valve..something there on the carb isn't adjusted right, seems to me like it could be a misadjusted carb. Just a thought.