G Day everyone!

Firstly this is my first time working on a Honda. I previously worked on a 1957 MG and a Benz W124. I am very excited to learn about Japanese cars and hope to get some help regarding this issue.

I recently started working on my grandfathers 1992 Accord EX. It has been sitting for 4 years with occasional starts.
I finally found the time and brought it home to work on it.

so far I removed the carb and refurbished it with a rebuild kit from Napco. Renewed all cracked vacuum lines. My grandfather had the complete shop manual which helped especially when replacing the vacuum lines.

The car cold starts and high idles but when I blip the throttle, the idle drops and runs rough below 800rpms. When I give it gas, it sputters, sometimes dies or sputters till around 3k rpm. After 3k, it revs smoothly all the way to red line. No issues with WOT.

After letting it warm, the idle is uneven at 1K rpm. You can hear some sort of miss.

The car drives brilliantly however and after a few kms after warm up, the idle is smoother with a slight sputter between 1k-2k rpms on acceleration.

I suspect (I may be wrong) it is running lean. I attempted to adjust the mixture screw behind the carb but it made no noticeable change.

I desperately seek some advice as I simply can’t find any information about tunning this carburetor.
thank you!

 

It can be tough to diagnose just from hearing symptoms.

One thing to check is to remove the air filter and see if it is kicking back through the carburetor as that could indicate a timing, spark misfire or even a valve issue.

Can you upload a video of the engine doing this so that we can hear/see what is going on?


**Spraying starting fluid around the engine while it is running can help check for vacuum leaks as it would make the engine rev up. Things like wd-40 would slow the engine down but can also be used. Just be sure that the sprays are not going directly into the carb as that would give a false reading.

Sometimes a vacume line might have a one way check valve in them. Having one of these in backwards can cause similar issues.

 

Dear Micro1989lxi,
Thank you for your response! I will for sure upload a video soon. Apologies for not doing so earlier.

I am currently running without the air filter housing as I find it easier to access the carb and vacuum lines.

I would like to note that when I manual close the choke slightly (when engine is warm), the idle increases and is stable and smooth. I also checked the valve clearances and found cyl 1 and 2 exhaust tighter (very odd). Sadly however it made no noticeable difference.

I hooked up my vacuum gauge (to brake booster line) and it is reading a healthy and somewhat stable reading when I manually hold the idle at the carb. This leads me to believe that there (hopefully) aren’t any vacuum leaks.

I have a small question regarding a few vacuum line which the shop manual does not highlight. They don’t seem to have vacuum. Unlike the other old lines, these had fallen off onto the garage floor and I am finding it difficult to retrace where they go. I will upload some pictures and videos tomorrow.

I am convinced this is simply a carb issue and has nothing to do with ignition. Spark plugs are extremely clean. I’d like to make the mixture richer since it seems to be happier with a little choke even when hot, how may I do so?
Thank you

 

"How to make it run richer."

This is only the second time that I have heard of an Accord from the 90's having a carb, thus I have never seen one.

"I attempted to adjust the mixture screw behind the carb but it made no noticeable change."
If there are adjustable fuel mixture jets, turning them out 1/4 to 1 turn would make the carb run richer.(globally richer)
If they are adjustable air jets, I think turning them in gives less air at idle only, thus richer upon acceleration.

My assumption is that this would not be adjustable at all on your carb from seeing 1980's Accord carbs. The only screw adjustments are probably strictly for the idle. (My assumption). Though you stated there there is one.

*If the rebuild kit that you used came with jets and you replaced the original Honda jets, I would assume that this is where the issue is. If there are metering rods internally, I would try the old ones or try an adjustment as this could change the fuel delivery off of idle.

*I forget if the secondary on the card is mechanical or vacuum. If vacuum, you could be losing vacuum where it bolts onto the carb, assuming that it seals with an O ring. Sorry, I have worked on so many different carbs, I forget exactly how Honda did all of these things back in the day.
I don't think that they did not use a vaccum assist dashpot to pull the linkage open for the secondaries, or you could check that to see if it was losing vacuum from there.

*You could also try pinching off (blocking, pliers, bolt in the hose) each of the vacuum line individually to see if there is an issue there.

I know when these Honda carbs are working correctly they work flawlessly. When they are having an issue, it has always been difficult for me to track down.