91 honda with choke problem when cold

Hey guys...its been a while since my last post seeing things have been
problem free for the past year or so

I have a 91 honda 3-door 1.3l with 140Km on it. It is
carburetted with a manual (yes the cable one) choke. Ever since the
temperature has gotten cooler I've been having choke-related problems.
I adjust the choke prior to starting up and the car starts up fine.

Usually I wait for the car to warm up a bit and and then
release the choke, but lately the choke has been acting up...As long
as I don't drive around and let it sit idle, high rpms are maintained
(1500-2000), but as soon as I start to drive around and say I put it
in neutral (manual Trans.) the rev counter dips under 1000revs and
hovers there and in some cases even stalls the engine unless I hit the
gas. When warm the car idles perfectly.

I took the car to my local carb guy and he checked it
out...about a year ago he took it apart and thoroughly cleaned it. He
did find the choke cable slightly loose and he tightened it
accordingly and the mixture was slightly lean so he adjusted that
too...The choke does seem to be functioning slightly better as a
result but it still dips to just under 1000revs and hovers there...It
seems like the choke is not managing to remain "closed" when it is
given gas and hence not enough fuel is being siphoned off

As always any help would be appreciated....

Steve

 

You're in Malta, apparently.

You say "cooler" weather has arrived. What's "cooler"? 70F? It was -6F
here two days ago here.

1500-2000 is way too high for sustained high idle. That's fine for the
initial flareup, but after that you should be modulating it to 1000-
1500, then decreasing it as much as you can as quickly as you can as the
engine warms.

The sooner the choke is able to be pushed off, the better for the
engine. Extended choke use means lots of raw fuel being pulled into the
engine, very bad for the bores and bearings.

I'm not quite sure what you're describing here. From my reading, it
sounds like you're pushing the choke off all the way and the engine is
idling below 1000rpm. Choke off, you should be around 750rpm. Choke on
(warm or cold), it would be above that, actual idle dependent on how far
you've pulled it closed.

Could you clarify a bit?

 

Yes, correct

Cooler is 7 C for Malta...but given the humidity here its more like
3-4. I'm originally from Toronto so I know what real cold is

Sorry for the misunderstanding...1500 revs with choke ON (as in
choke light is on, and engine still cold)...When the car wamrs up it
idles perfectly at 750 rpms with choke OFF (choke light off and engine
close to normal operating temp.)

So the problem is when the car is still cold and with the choke ON the
revs fluctuate and are not maintained....with the biggest issue being
when putting the car into neutral after accelerating to say 60Km/
h...the revs go under 1000rpm with the choke still on and basically
hover there and might in some cases fall go to 0, stalling the car
unless I hit the gas. As soon as the car warms up I put the choke off
and the car maintains the idle rpms without hesitation. It seems to be
something of a mechanical nature I guess.

Sorry for the confusion regarding choke off/on....I know that in
actual fact the choke is physically closed when ON and fully open when
OFF....

Thanks for your reply

Steve

 

there are usually two parts of a choke mechanism:

1. the bit that raises the revs.
2. the bit that restricts airflow to make the mixture rich.

sounds like #2 is failing because if the mix is rich, it won't die when
you open the throttle.

can't offer more blind advice because i'm not familiar with this carb,
but suggest you take the top off and observe the action of the choke
plate. look for springs that are supposed to hold it closed, but which
are broken, thus leaving the choke plate open.

 

:

Does the idle
1) flutuate with a regular rhythm, hitting the same high and low points
each time,
2) does it hunt all over the place, or
3) does it settle to a steady but different level each time you stop the
car?

It does sound like an overfueling situation.

I'd check (as jim beam has stated) that the throttle-opening cam is
actually engaging and holding the throttle part-open when the choke is on.

If the throttle is completely closed with the choke on and the engine cold,
the engine will stall.

Haven't worked on a carb in years, so this is from memory. The fast-idle
throttle-opening mechanism usually involves a stepped cam on the throttle
spindle, operated by an adjustable screw on the choke mechanism. I've seen
the screw bent off to one side, loose, or otherwise not contacting the
stepped cam properly.

I think you need to visually and carefully inspect the linkage and its
motion. This can be done while the engine is off.

 

In Honda carbureted, the fast idle unloader will pull the fast idle
cam and release the choke when the engine reaches normal temperature
But in these cars, the gas pedal will override the FIU and release the
choke if you press it during the warm up process or any time after
starting. Your boss is a prick and you may be late for work, no?

What you have experienced is not about the choke not remaining closed
as it should, it's about the choke staying open when it should NOT.

It's OK to reduce the warm up time in summer and you won't see any
anomalies if your ignition is super strong. But you'll see all the
kinks if you do so during winter time with weak ignition. So give her
a complete tune up and let her warm up a little bit before you want to
ride her hard..

 

Oops i didn't read the part that says your choke is manual, my bad!!

Give her a tune up anyway, symptom that looks like fuel related may be
in fact ignition problems

cheers!.

 

Update: After playing about with different choke positions with the
manual knob I found that setting it to the first position...i.e. least
choke, the choke does not exhibit any of the issues mentioned
above...In fact the problem has arisen since I've used this setting...

What this means I guess is that the problem is probably what Jim/
Tegger stated and there is some mechanical issue relating the throttle-
opening cam is exhibited when the choke is pulled beyond the first
position....I will confirm this when I have some time to take off the
air cleaner and visualise it myself...


Thanks alot for your help/time guys...much appreciated