I have a 1977 Toyota 20R pickup. It had been setting (recked/undriven) since 2009. I became the new owner this year and have been working on it. It did pass smog (A MIRACLE) in June (this year). I have replaced many parts that was rusty and warned. I love this truck! I have done all the work myself and wish to continue doing so. But I am stuck right now with carburator a issues. I have studied and studied everything pertaining to my truck. I am pretty sure my problem is the fast idle cam. I believe it is getting stuck when I could start and unsticks when truck starts warming up. It is a very high idle until then. The carb. is OEM. Poor baby is in need of a lot of TLC. Other then that my baby runs great. There could be something missing that connects to it. I can't seem to find a good picture diagram to compare it with. Can someone please give me some input to help me figure this out?

 

Here are the starting procedure for a 22R. Probably the same for a 20R. After starting the truck, if you hit the gas pedal once does the idle decrease?

 

You can spray carb cleaner on the linkage. Don't use anything that's sticky or leaves a residue to clean or lube the linkage.

If you don't have a copy of the service manual, you can download one from this link.
https://web.archive.org/web/20110102...ttora.com/FSM/

 

Your truck series (RN2#)went until 1978. In 1979 the new series became RN3#(2wd) and RN4#(4wd).
If you don't have a repair manual, a very good one that was close to factory quality is Bentley. I don't think they have one for 1977, but they do have one that covers 1978-1984. It might be the best you can get.

15 years is a long time to sit. If it was my carb, i'd source an overhaul kit that has all the gaskets, new float, and needle and seat. Then I'd get a can of carb dip and pull the carb horn and clean, then the carb body. Obviously remove anything rubber or electrical first. If you have access to a large ultrasonic cleaner you could do that before the carb dip. I wouldn't try and remove any of the brass jets, etc. Just strip down enough to safely clean.
After cleaning, reassemble, using the instructions with the kit on setting float height, and see what you got.

 

If it passed smog in June the carb probably doesn't need an overhaul. I would get a carb rebuild kit just to have on hand. Check RockAuto for a kit. If anything is going to go bad it's the diaphragm on the AAP.

Ebay has a lot of Chilton's repair books on these trucks.
https://www.ebay.com/itm/13532981767...90.c101224.m-1


Pic of a 20R carb from my Chilton's repair book.

 

I have been wanting to get a carb kit but haven't had any luck. I will check Rock Auto right away. Thanks. And thank you so much for the eBay link to get my own book. I ordered it right now. I was so pleased that it was so cheap lol I have wanted so desperately to take that carb apart and clean it up. It is so dirty looking inside. Cleaned outside real good. But I am scared that I will do something wrong. With the book I can follow instructions really good. Thanks so much for your help. I am going to do it as soon as I get my own book from eBay. I am going to check that AAP first thing in the morning to see if it's working properly. Will let you know

 

If the AAP was bad, you'd know because the truck would idle like crap. I rebuilt my carb several years ago. My AAP had gone bad. Rebuilding is not hard. I did have to make some tools to work on it. I had to bolt it to a piece of wood to get torque on the air horn screws. Putting the carb back on, I had one of the nuts on a stud bold strip and had to use a dremel in a tight spot on the truck to get the nut off. After the rebuild, the gas in my float bowl evaporates where prior to the rebuild it didn't. There are many references to this online but no solution. Hindsight, I should have just replaced the AAP diaphragm and not pulled it apart to clean. Before the AAP going bad, the carb/truck ran fine. It sounds like your carb is also running fine since it passed smog in June. If I were you I'd not pull it to clean it. Would you have issues with a rebuild, maybe, maybe not. Save that project for when the carb is truly problematic and warrants a rebuild.

 

Well I think you are right. The AAP is bad. Can I fix it, or do I need to replace the AAP altogether? I received my repair book and have read it from front to back. Thanks for the hookup. I am on Rock auto's website right now. Does the carb repair kit come with something to help the AAP also? My truck is sounding like a bull horn when I put it into gear. Very not cool. I feel like I am hurting my baby!

 

Another thing I noticed is that the spring that connects to the choke breaker is SPRONG. It's loose and not having any effect linkage at all. Would that be a reason why truck,when cold starting, remains at very high idle until truck starts warming up? Taping gas pedal doesn't work to slow it down at all til truck starts warming up.

 

There should be a diaphragm in the rebuild kit for the AAP.

Please post a pic of the spring you think is shot and a pic of the carb.

 

I saw that diaphragm in the rebuilt from that RockAuto. I was wondering if that would be it. thanks. And I'll go take pictures of what I was talking about with spring and of my carburetor.

 

I'm sorry I am having a problem downloading the pics. Don't know how I'll keep trying

 

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