My 84 F250 with 4-spd and 300 CID engine runs great except for the warm idle speed. It idles too fast. Just guessing here but maybe in the 1000-1100 rpm area. Cold idle speed seems about right and it runs good when cold or warm. Also starts easily. I gave it a tune up when I bought it. Warm idle speed should be 650 rpm or so. Occasionally, it idles at its usual too fast speed and then drops down to the correct speed for a while. I had the sensors checked. The O2 sensor was OK but the TPS was bad so I had it replaced. Truck failed emissions test on high CO when idling. All else passed OK. I'm thinking that it is either a carb or a vacuum problem. Truck is a CA model and has a computer on-board. I haven't dug into this problem yet and was hoping that someone would have seen this before and KNOW what the prob is. Any idears on the best / most likely place to start working on this? Thanks for any suggestions.

Ed

 

If it says "EECIV" on the radiator sticker, you should be able to read any codes from the computer. A error code may give you a hint to whats wrong if there are any.

 

Thanks for the reply. Yes, the radiator sticker mentiones EECIV. Also that the carb is computer feedback controlled and that the idle and fuel mixture are not adjustable. What the heck? Being able to adjust these things is the essence of having a carb. This is looking a lot like one of those tweener deals... with the worst attributes of both. :-(

Ed

 

I haven't worked on that exact carb, but most are adjustable after you rebuild them. Some of them you have to take a chisel and knock out some aluminum plugs they drive in to cover them up. Some of them you have to break off some plastic things to get to them. The explain it in the kit.

 

It's a Carter Y model 1-bbl. carb. I haven't looked at it closely but will do so shortly. Thanks for the info on the plastic covers / aluminum plugs. What I can see of the carb at a casual glance looks relatively new so I don't know if it was rebuilt by the PO, just cleaned up, if it was a recently installed reman unit, or what.

Personally, I would rather have a 2-bbl. carb of about 300 cfm on there but, for emissions testing reasons, can't do that until the truck is 25 years old... which it will be in 2009. I just need some tweaking to get me through the time between now and then. I appreciate your comments.

Ed