79 toyota 20r

30

Asked by Nov 13, 2019 at 10:41 AM about the 1979 Toyota Pickup

Question type: Maintenance & Repair

I have a 79 Toyota pickup 20R. That starts fine warms up
fine and then we'll idle down and running to normal idle all
the way up until it gets to complete temp when it is
running like this it is a little sputtery when trying to run
down the road in a steady RPM but other than that runs
fine I have done plugs wires adjusted the timing done
seafoam treatments adjusted the carburetor and still
once it hits Complete full temp like a switch it run smooth
down the road and idles high will not kick down if I tune it
to where it'll idle normal while it's idling like that it'll run
fine until I shut it off and go to drive it again and then it
goes right back to the same thing I've traced all the
vacuum lines they're all hooked up to the right spot and in
good condition I'm not sure what else to do short of
rebuilding the carburetor.

14 Answers

268,865

A rebuild or replacement of the carb would probably solve the issue.

1 people found this helpful.
30

Thanks that's what I'm thinking. Idk what else could be causing the issue I'm pretty mechanically inclined and I've been through it pretty thoroughly. I have even tried adjusting it a few different ways to try and get the throttle linkage and the carb adjusted to where it would counter for the issue and it still tends to go right back to what it was doing the next time I go to Fire and drive the truck or once it hits that one point where I would normally idle up it just won't stay running and I'll have to completely tune the carburetor back up to standard to get it to fire and stay running

1,400

distributor vacuum advance valve malfunction ?

1 people found this helpful.
30

Is there a way I can check that

30

And that's the vacuum diaphragm on the distributor right

1,400

Yes on the distributor. To check it I am sure there is but you may have to google that for the answer. Or F_O_R might know as he is quite knowledgeable

1 people found this helpful.
268,865

You can use a timing light to see if the vacuum advances the spark or not. If you do not have to pass smog I would install a Weber carb instead of the stock one. Even if the vacuum advance does not work the mechanical advance should still work.

1 people found this helpful.
1,400

The Weber may get you a few more speeding tickets as it will increase the horsepower going from a single port to a double.

1 people found this helpful.
30

Thanks il give it a try. As well as planning on either rebuilding carb for now. But do plan on ditching smog and putting on the weber

30

Just on a budget for now

30

Iv only ever rebuilt small engine carbs is there anything I should keep in mind or look out for when attempting to rebuild my carb.

30

Iv looked all over online and done a bunch of research and I cant find any good diagram or videos on rebuilding that carb. Several on 22re carb but not 20r

268,865

There are stock type replacement Webers and the high performance type. I don't know about yours but smog carbs are very complicated and have a "million" little bits that you can lose. They are very hard to get right.

1 people found this helpful.
30

Ok thank you for your help. You have been very helpful.

1 people found this helpful.

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