89 honda accord cold start problem

This one has me stumped,… the problem only occurs on a COLD start.
I put the key in and start the motor. It starts fine.
It runs fine for about three(3) seconds and then the RPM’s start to dive (I have to give it gas to keep it from dying).
The exhaust begins to put out quite a bit of smoke and the engine runs really really really rough,… kinda like it has a heavy cam in it.
After a few minutes of this exhaust smoke and rough running, the engine of course is warming up.
The RPM’s start to come up on its own, the exhaust smoke disappears and the really really really
rough idle (not really an idle because I have to give it gas to prevent the motor from dying) disappears and the car idles perfectly.
This cold start problem also uses up a noticeable amount of gasoline.

Anybody have any suggestions on what to look for/at to solve this problem?

Does this Honda use a carburetor or is it fuel injected? I ask, because my 1990 Toyota p/u had a similar problem. A Toyota trucks forum explained the answer was due to the Auxillary Accelerator Pump leaking fuel. Since the AAP was operated only by vacuum and only when the engine was cold, the problem disappeared when the truck warmed up. The quick fix was to disconnect and cap both the AAP and the vaccum line that fed it. The permanent fix was to rebuild the carb. The kit came with all the parts for the AAP.

If it is fuel injected, you may want to look for a cold-start injector. If yours has one, and it leaks, this could also cause the problem.

You say it has you stumped - which implies that you’ve done a bunch of stuff. Maybe if you’ve done a bunch of stuff you could say so. Its also necessary to tell people, at minimum, which engine is in it. Or at the very least, noting whether its a carb or fuel injected would also be a bonus.

Honda was one of the last to switch to injection, so like Busted said, we need to know if it has one of Honda’s famous feed-back carburetors…

What color/smell is the smoke?
It could be head gasket seeping coolant into a cylinder.

Sorry about the lack of information…I should have known better!
It’s a carbed 2bbL, engine is an A20A1

Okay then, it sounds like the choke is not opening as designed. When the engine starts, there is usually some sort of vacuum operated “choke pull-off” device. Your choke seems to staying closed, shut tight, which will quickly flood the engine…

You should know that your car is cursed with one of the most complex carburetors ever made…Carefully remove the air cleaner, the entire housing, and take a look at what you are dealing with. Does the carb have 20 or so spaghetti-like vacuum lines connected to a control unit mounted on the firewall? This is as far as most mechanics get…Good Luck…Sometimes you can rig a hand choke…

It does have a big bundle of vacuum line going to the “black box”.
Any suggestions on how to disable the choke? BustedKnuckles suggests its the AAP…
I guess I need to disable one thing at a time to see which one is the culprit.

Update…I went out to the car and checked the carb, the choke butterfly was closed.
I started the car and hopped out before it started doing its thing…then it started doing its thing…
I then open up the butterfly. Tadow! No rough running, no smoke. Its the choke!

Its the choke pull off. There is a diaphragm attached to the choke linkage that uses manifold vacuum to open the choke slightly as soon as the manifold gets a vacuum from the engine running. It could be the hose to it, but more likely the diaphragm. This affects the car when warm too as it is a vacuum leak.

Also, check to see if the choke plate can move freely. If it feels like it is sticking, a good cleaning with carb cleaner may help. Concentrate the spray at the shaft bushings and the linkage to free up any rough movement.

I’m flying blind now, its been a long time, but as I remember, the pull-off for THIS choke is internal…On another forum, someone posted this…

1986-1989 Honda Accord with Carburetor have a very bad habit that is little known even by most mechanics but easily fixed at home. The vacuum port on the choke opener that is connected to the intake manifold and both vacuum ports on the fast idle unloader get plugged up with nasty hard carbon almost as hard as metal. When this happens the choke sticks closed and the idle sticks on fast idle when the engine is cold and nobody can figure out why. All you have to do is attach a small drill bit to the end of a flexible socket-driver extension and put it in a variable speed drill that will let you run it real slow and carefully drill out the vacuum ports that are plugged. After they are nice and clean use a vacuum pump tester to make sure the choke opener and fast idle unloader are working before putting it all back together.

But this guy fails to mention exactly where the plugged ports are located…But at least now you know what the problem is…

I did notice that suggestion (drill bit) was in the shop manual, but I have not had a chance
to perform it. I was working on borrowing a vacuum pump to test the choke opener because
I think the diaphragm has a leak. I was also searching for a carb rebuild kit which contains the diaphragms
for the choke opener and the aux accelerator pump. The other day when I was inspecting/messing with the choke, I noticed that the flex boot on the AAP ws cracked and disintegrating. Any suggestions on carb rebuild kits to obtain these parts if necessary?

BTW, thanks you guys for all of your help and suggestions!

You may have to buy these separately and from a dealer. When you see the cost of these parts, you might look up the cost of a Redline Webber conversion kit. The Webber is not an ideal carburetor for a cvcc engine, but it can be made to work, or at least it has been done.