Carb issues- fast idle??

[86dxhatch]

I've been having some issues with cold fast idle... One morning a few weeks ago, I started my car like usual, set the choke, crank the car... It started to high idle just for a few seconds, but only at 2k, then it dropped to around 1.1-1.3k.

Since then, it only high idles properly about 15-20% of the time. When it doesn't high idle, it runs rough, shaky sputtering... When I give it a little gas and it smooths out above 2k. After a min. or so of running the fast idle then comes in.... up to 3k.

The funny thing is, when I put in the clutch, even in neutral, it drops my fast idle about 1k rpms. let it out, and it starts racing again.
It usually takes a couple minutes of driving for it to warmup, then idles down.

When it starts normally, it doesn't take as long for it to come off of high idle, but when it acts up, then finally high idles, it takes about a minute longer than usual to come back down....

Has anyone had similar problems?

[CzEcHy]

3k is a bit high to be fast idling, it should start out at between 1100 and 1500rpm then slowly go to 2500 max..


I had the same problem with the stock carb on cold days (I'm in FL too). All I did was start car, and hold the gas for more than 20 seconds at around 1500 rpm, and the fast idle would sort itself out and I could let off the gas and it would hold at 1500, which was more than enough to warm the car up and honestly I think 1500rpm is perfect for fast idle max speed anyway..

.I switched to a weber so I never got the problem totally sorted out, and my weber has annoying fast idle problems too, but I just manually hold the gas for a bit then let my foot off and it usually fast idles by itself fine.



You have a fast idle screw located somewhere on your carb, I forgot where exactly it was tho sorry. It may just be misadjusted and the change in weather is letting you know to adjust it.

Also, to bring down the fast idle just tap the gas a couple of times, you may have to rev it to 4k or so but it should come down as long as the car is actually warming up (coolant needle being at the lowest line on your gauge should be good enough). Ill try to remember where the fast idle screw is or maybe another member remembers where its at.

[g.frost]

With cold engine, take off air cleaner. Push gas once to floor to set choke. Check that choke is closed.
Start engine. Check that choke is partly open.
If it starts to run loopy, see if opening or closing the choke more helps.

When warmed up, if the idle is still running too high: is the choke fully opened? If not,push it open, better? If so, points to choke opener or choke heater.

Take your vac gauge and tap into line 18 on the choke opener. Is there vac? If not, unplug 18 from choke and see if you can pump it down/should hold vac. If not then it is towards thermovalve A or fast idle unloader; check for leaks along these lines as well.
... should check vac line 26 on choke opener as well: opener should pull vac and line 26 should hold vac accept when cranking engine.