Air mixture won't adjust

[PlainJane]

Hello, thanks for looking at my situation.

I have a 1983 with a mixture screw that won't adjust the mixture. Let me preface this with an anecdotal story:

The alternator was replaced a couple of years ago with the incorrect regulator installed. Once I changed the regulator, a fuse blew. I wasn't able to drive without the choke to keep the engine at or above 1000 rpm. After I had the fuse checked, I enjoyed a week of blissful driving before the registration became due.

Last year it passed smog after fiddling with the idle mixture screw. This time, I can have that screw out 4+ turns with no change in rpm. It stays at a steady 500-600 rpm no matter how much that screw is out.

I've had problems with Toyota service in the past, and since I'm a lady I'm not sure whether or not mechanics are trying to milk my wallet. Any suggestions would be greatly appreciated.

 

[2mbb]

If your truck has the smog equipment, and you intend or need to keep the equipment, you should get a copy of the 2F emissions manual. you can purchase a paper copy from toyota materials distribution (do a search) or download a copy here: IH8MUD.com - View Single Post - Rough Idle / Dies at Stops / Carb Issues. My local dealer had to borrow my copy when I made the mistake of bringing the truck to them for repairs a ew years ago.

The method for adjusting the carburetor idle mixture is called the "lean drop" method. Here is one post of mine on the subject: IH8MUD.com - View Single Post - carberator

Before I start adjustments I usually screw the idle mixture screw all the way in, then back it out two full turns. This is a good starting point for the lean drop method. As I'm doing the lean drop, I only move the screw 1/4 turn at a time, the pause to see if the idle speed has increased. That way I can always go back to where I was if that was better.

Good luck!