Hi folks...I'm new to the forum and need help. The subject truck had a "new motor" swapped in prior to purchase. the emissions system is a mess and it's running very rich with poor idle and stalling. I'm not looking for performace just reliability and ease of repair. I need to know how to swap in an earlier carb with out all the SMOG vacuum bells and whistles. will I need a new manifold? which carb should I use (pinto, 2V autolite or Holley, 1V autolite or similar?). the truck has a duraspark ignition,(single spark plug per cyl.)Is there a computer in this model year? will it need to be modified? how do I delete the smog pump (save weight and HP)?This was also posted on the "Four Banger forum but there were no takers, PLEASE HELP!!!

 

I owned an 84 from 83-92 that had the 2.3L engine. There were two systems that year, one was called an altitude calibration that was strickly mechanaical and the other 85-90% had a system called MCU. Microprocesser Control Unit. The MCU was contained inside a plastic box on the passenger fender apron. It consisted of a bunch of vacuum electric do-dads. I replaced the carb around 70K because it kept failing emission tests. The carb had a thing called a "dithering valve" that oscillated between rich and lean all the time. If it failed in the lean mode, it passed emissions but lacked power and had spark knock, if it failed in the rich mode, it failed emissions but ran fairly good. I can not remember if it had electric choke or hot water heated choke. Maybe somebody can suggest a good replacement carb for you. I disconnected the air pump when it froze up and plugged the air pipe going to the catalyst. MTA, managed thermactor air was an attempt to introduce more air into the exhaust system at the catalyst to clean up tailpipe emissions. I might have some old shop manuals somewhere for your year, but they would not list replacement carbs. Good luck.

 

Ranger Pat...Thanks for the reply...This truck has the "MCU" on the passenger side inner fender...There's some lines connenected some are not. Florida does not have tailpipe sniffing yet Hence the desire to strip the Smog Stuff and go back to what works.
Before I get spammed with the negative I agree with clean air requirements but this thing will run cleaner with a properly tuned engine than what I've got going now.
Again thanks Pat

 

I have an 85 with the carbureted 2.8 V6. When I first bought it, I was having some of the same problems. It kept stalling all the time. I am still learning all the emissions controls in this thing, don't know them all yet. This forum is very helpful. What I did with mine was to remove the carb, pry off the mixture screw covers so that idle mixture could be adjusted like an old carb, and reinstalled the carb leaving the electrical connection for the internal emmissions controls OFF. I disconnected several other controls also, all in an effort to get the mixture going to the engine to just stay steady (even if not exactly correct ... a little rich, and not capable of passing emmissions). Surely you've guessed by now that this truck doesn't get sniffed yet. When that day comes, I'll have to fix it RIGHT. But for now, it runs really good.