84 Mazda Idle Issues

I have an 84 b2000 SE-5, when I first got her as a gas saver for back and forth to work, she ran great. Now she won't stay idle at all, and has trouble starting. When it does idle, it's a slow idle and extremely ruff. I did replace plugs and wires, but I am starting to think this might be a carb issue. I did talk to a mechanic, who told me to check into the idle control solenoid, but ill be dammed if I know where that is or how to replace it.

She runs great once you get her going down the road, yeah its a beater but I can't complain about the gas savings, considering my commute is going to be 30 miles each way here starting next month, so I would really like to get her road worthy again.

So any suggestions on where to start?

First off, stay away from that mechanic! Idle control solenoids are only found on fuel injected engines, which wasn't common until the late 80's. You have a carburetor, which has a few different adjustment screws. The one that controls idle speed is acting as the throttle stop(I wish I was more familiar with the 84 carb, so I could tell you exactly which screw). Find it, and turn it in until the idle reaches the rpm you're looking for.

behind the carb there is a bolt, on mine its a huge bolt and you should be able to screw it one way or the other and it will hit that throttle plate, i will try to get a pic of mine but i think my bolt isnt even the right bolt haha.

this is it, best pic i could get this soon

So I had a few mins to work on the B2K the other day, I couldn't find the bolt pictured, but I did find this.




I pulled that little plunger out a bit and she fired right up and idled great, for a short time until I actually drove around a bit. Then it was back to the same old issue. I assume this is some type of idle control plunger of some type. Thinking it may need replacement?

That is prob it, and mine very well might be rigged all dumb by previous owner heh. Maybe its dirty and gunked up? I always try wd40 or carb cleaner before I have to get a new part dew to the fact that I can ever find any damned parts!

No, that's not it! That's your dashpot... it's used to dampen the throttle when closing.
Your having adjusted it should do the job, but there is supposed to be a screw dedicated for said adjustment.

Problem is that pulling it out didnt fix it. It fixed it for a few mins until the plunger just went back too far to keep it running. The other picture looks like someone just replaced the dashpot with a bolt.

Been researching a replacement part, but havent found one yet. I found a generic part at autozone, but I am not sure if that would be a suitable replacement.





I dont want to just rig it up with a bolt if I can avoid it, looks like a run to a junkyard may be in order this week.

Still cant find an idle adjustment, and my google research is not getting me any results.

have you taken off and cleaned your egr? with that one i know they can get gunked up and some carb cleaner and a smaller brush will help. just make sure to not mess up the gasket or get a new one. personally i think junkyard routes are the best way to go if you find something. good luck finding a 1st gen though none of mine around here have them and its no bueno

Well I spent the day getting the "B" back running, I finally found the idle speed screw, I have attached a photo of the screw location with the hope of helping a fellow 84 B2000 owner fix his/hers some day.






The red circle is your idle speed, after some adjustment I got it to hold an idle. I still have a tune up to do with this thing, I may replace the EGR valve here next along with the fuel filter.

The blue circle is the back side of your dashpot, I also made some adjustment to that as well. I am standing on the passenger side of the pickup in this photo.

Well onward to the next tune up stage...