81' Honda Civic Carburetor

I Have an 81 Civic that has recently been having issues with the carburetor. I had got a used carb at pull & save, and it worked great for a while, but it’s now got a hesitation. it’s kinda like it will be trying to go, but just can’t quite. I found a hole in the vacuum diaphragm that opens the second butterfly and replaced it, but with no avail. I think it might have something to do with the float screws, and there adjustment, but so far, nothing. If anyone knows anything about old civics, and, or, but not limited to mine, would you please offer your sterling contribution. Thanks and all that…

P.S. The Cartalk Community is my last resort, you guys are awesome. (a little flattery never hurts.)

Carbs can be tricky to get adjusted correctly. The best suggestion I can offer is to get a repair manual for your Civic. That should talk to carb adjustment. One should be available online.

the only manuals I can find only go back to 84. they changed the whole car in 83, so i’m stuck.

Try these links:



I hope you didn’t put a screw driver into the slot on the top and turn that screw. I believe that you have a 3 bbl carburetor on a CCVC engine and often the problem is in the valves and ports to the pre-combustion chamber.

I would replace that carb with a Weber DGEV carburetor.
Search the web and you’ll find kits with an adapter plate.



Thanks for the links, the only problem is $$. i got the car for free and, (being only 16) i don’t have much money, and don’t usually get stuff. I was sort of hoping someone would be able to just tell me what’s wrong. the car in and of it’s self isn’t worth enough to spend money on it. believe it or not i have turned the screws on top, at least if you mean the float screws… Bad idea i know, but hind sight is 20/20. the place i got the carb it cost $9, just they don’t always have the right one. i just have to keep looking.

There is a fuel cut off solenoid that can fail, nearly totally shutting off fuel flow to the main bowl. Do some research. It’s been years since I last opened one of those carburetors but the most common problems were a punctured float, failed shut off solenoid and gummed up auxiliary valves and ports.

i’ve checked those, the valve had some problems, but i fixed it. i cleaned everything else. it’s a real nice carb, just it doesn’t work. i think someone rebuilt it.

You have picked one of the most complex carburetor setups that ever existed. If its the right carb, then it is a 3 barrel, but one of the barrels is very tiny, and on top of all that, you must have 100 vacuum hoses, not really that many but it looks like it.

The issue you are describing could be the accelerator pump or a vacuum leak. Remove the air filter, look down the throats of the carburetor and open the throttle (engine off) and see if any gas is being squirted into the throats. It should be a pretty strong stream. If not, then you need a new accelerator pump diaphragm.

If you get a good stream, then start searching through all those vacuum hoses for a leak. Good luck. BTW, I don’t think a Weber is a good idea for this car. It works for almost every other car built in this era, but not the CVCC engine.

Sounds like an accelerator pump problem on the carb. Remove the air cleaner and with the choke flap held open work the throttle lever by hand.
Each time you open the lever you should see the discharge nozzle near the top of the carburetor on the primary side squirt a stream of gasoline. If not, the problem is in the accelerator pump circuit.

Possibly a failed plunger but more than likely a stuck check ball or crud blocking the pump circuit.

I know for a fact that the accelerator pump works perfectly. it is a 3 barrel carb, i’m not sure what the brand is, the name starts with a k and is Japanese. (more suggestions?) PLEASE please please please…
All of the comments so far have been good common sense ones, the only problem is the issue does’t seem to be a common issue. hence cartalk.

Common sense is one of my few assets, bemehiser. There are almost certainly 2 boxes of carburetor controls with a plate full of black spaghetti connecting them to the carburetor and ancillary emission devices. The carburetor’s auxilary system must function to get combustion started, Even with the car in front of me it would require testing several separate functions and that leaves it up to you. You might carefully dribble fuel down the aux venturi to isolate which side of the carb is failing.

I’ve thought of trying that, the only issue is that it runs great at an idle, the problem is when i try to drive it anywhere. i would try that except my brother doesn’t like the idea of riding on top of the engine dribbling gas into the carb at 50 mph.

thanks for the thoughts.

It’s a Keihin carburetor and you state the accelerator pump works perfectly.
I ask how do you know this and/or how have you verified it?

I’m not being combative; only trying to make sure this is not a case of a dog chasing its own tail.

If it idles fine then the idle circuit is ok.
If it runs fine at speed (say 55 MPH sustained) then the main jets are not clogged.
If it idles fine, stumbles on acceleration, and runs fine at a steady elevated speed then it goes back to the accelerator pump.

While this won’t help you, a reason it’s hard to tell you what to do is because this car’s system was both complicated and unusual, no other maker went with the CVCC system, and Honda only used it for a relatively short while. This era was the WORST to try and fix.

GOOD GOLLY MISS MOLLY…Are you boys trying to troubleshoot one of the most Mystefying, vacume tube laden…Black magic practicing… Honda Keihin Carbs in EXISTENCE NOW OR FOREVER…DO you have any idea what you are looking at ?..LOL… Sure you know what your messin with? I think many of us on here of a certain age know carbs…I know them well…but I will be blunt…when Honda esp came out with their Carb systems (by Keihin) in the early to mid 80’s I tell you that I had never EVER seen any other conglomeration of electrical and vacume operated fanciness in all my days…

I still have nightmares about tagging all those vac lines and generally getting all the carb parts back together properly…LOL… Perhaps you are lucky and you DONT have a unit as complicated as I used to play with.

BUT as usual OK4450 has it right again… The first thing that came to my mind was the accel pump…(It is one of the MOST vigorously moving object within the carb aside form the butterfly shaft) Now if you dont believe us thats fine… However this can get WAY over your head WAY fast… Cause if I have trouble with them…I promise you that you will find the same or worse…NO OFFENSE… But I was born with a carb in my Diaper and I dont like to mess with these much… But I have …and I’m good. Most times I win…but there were some dark days my friend, they still haunt me… ALAS…

Have you tried to spray some lube around the butterly pivot area? Many X the bushings wear out at the shaft…and the carb sucks air in thru this gap…virtually no way to repair this…tho I ve tried. When this happens it leans the mix out…bad…

Look at your accel pump…look for VACUME leaks…at the shaft as well as elsewhere…check your timing (ignition)… Also you need to verify the float level… fuel filter integrity…Fuel pump operation… Have you located your mixture screw? DO THEY WORK…or are their internal ports so screwed up that the mix setting make no difference?

I could go on and on and on here…BUt to be honest I would really need to be there to take the “pulse” of what is happening…there are many clues you are presented with and unfortunatley you may not recognize them…this is getting into GURU territory… A place that I frequent, yet never remain



Makes me smile that you know what I am talking about…Jesus…those systems

Got to admit…those systems worked VERY nicely…and rarely had issues…Methinks you are suffering from issues from SITTING TOO LONG…which means you need to clean the carb and get all the moalsses out of ever single passageway in that carb… This will wreak havoc on your system. Texases states it clearly…these were complicated systems… All we can do is guide you…How commited are you? I know I could get close to solving the issue…but it would take near all my Super Powers.,I promise you…and thats with me there and in person.

Go thru all the basics…Make sure the carb is clean…then follow every piece of advice these guys give you… With persitence it will pay off… CHeck for Vac leaks…this is very important…as it throws almost everything else off… Trust me.

I have played with it while it’s idling, pulling the accelerator cable and such, and have clearly seen a goodly squirt of gas come from the accelerator pump.

It doesn’t run good at speed. It feels like it’s bogged, and has little split second surges of power like it’s trying and something’s holding it back.

it has the same problem on acceleration.
I thought that the vacuum diaphragm for the second butterfly would fix it, but no luck.