Runs best when cold and bad when warmed up

My 89 Accord DX with the carb motor runs a little sputtery after it is warmed up while driving.

Things I have done so far:

-Ran some seafoam through the tank with fresh gas and a little into the carb

-Used some regular carb cleaner to clean best I could

-New NGK Wires & Vpower Plugs

-Distributor is only 3 months old, guy had some receipts when I bought it

-Basic Tune-Up oil/air filter/plugs etc

-New PCV valve

-New Fuel Filters both of em

-Spent sometime checking for vacuum leaks nothing that I can find

-Checked the ignition timing according to the manual and its on point

I did find the tubing that comes off the exhaust manifold to the carb, I believe this lets the warm air into it during warm-up. It's like flexible metal dryer duct. What pinched and broken at one spot which explained the gas/burn smell I would get. I have it temporary rig with some foil tape until I figure out something with.

It will start up rough kinda like dieseling as described by some users on here. Does that for a minute then it revs up to 3,000 and hangs there for a few minutes. Strange thing is that if I drive it while it's doing this high 3,000 rev/idle it seems to be running smooth when driving. No sputter/bucking when I'm accelerating. But after it's warmed up and it idles down around the 750 - 1000 range it will sputter/buck while driving. Sometimes it's drops low in idle when braking hard but never has stalled out on me. When it is warmed up the idle does hold pretty solid around where it should be no issues with it dropping or anything when still.

Just looking for some input. I did search around here and have tried a few of the issues with no luck. I checked the venturies I believe their called. They did not wiggle or feel loose.

Does the exhaust smell like fresh gas when it is warmed up?

Yeah, it does kinda smell like gas a little. I also noticed this too today; when leaving from a stop i jumped on it running through the gears and it seemed to run smooth but i let off the gas a little to slow down and soon as i got back on it started getting sputtery again on me. I did find a similar post I think it might have been on here and his source of the problem was cleaning the egr valve and ports. ill check it out saturday.

Check your choke operation too.

Check the valve (flapper door) in the air intake and see if it hold vacuum. This can be a tricky vacuum leak to find by other methods, and it sounds like a vacuum leak to me.
The other thing to consider would be the high idle choke pull off as the diaphragm is internal to the carb making it also a hard leak to detect.
Good luck!

hey guys sorry for the delay. had some things to take care of. im messing around with it now and i just got my new flexiable exhaust hose installed that i got from mcmaster carr. after removing the top filter area i noticed a vacuum port off to the back that had no line on it. i haven't found another open port yet so i'm not sure if that is suppose to be open like that or not. pictures below....

http://s23.postimg.org/rlbfkbeon/photo.jpg

http://s23.postimg.org/q4zx26brr/photo_1.jpg

and this mystery vacuum port

http://s23.postimg.org/3vlzvmgbb/photo_2.jpg

again sorry for a delay but i got a call for some work...just got laid off thursday so when side jobs call its 1st priority. Anyways, I found the exit to that vacuum port and it does not hook to anything. It's almost like an extra one behind the carb assembly. Still have a burning/gassy smell so I spoke to a friend with a guy that claims he is a real honda nut. Guess I'll find out when I throw this mess in front of him lol. Yeah, so I was on the bank of just getting a new carb setup but due to me getting laid off it's Doller Zone mode now so I appreciate all of your inputs.

I would at least cap that vacuum port. That could be your whole problem.

With the engine fully warmed up and idling, check that the choke butterfly is straight up vertical.
What is the number on the vacuum tube leading to that open port? Trace the vacuum diagram in the manual.
I know there are some unused on my DX.

The vacuum port does not have a number and it goes to nothing, it's a hard line on the rack with the other ones and it isn't connected to anything on either end and I have looked over the lines and haven't found any open ports elsewhere. It's almost like a back up one maybe in-case you need it or something I don't know but I do not think it serves at purpose. Okay so when the car is fully warmed up and idling normal, the choke butterfly should be straight up vertically. I will check that out tomorrow right away. It still seems to me like it is getting flooded with gas possibly.

Definitely sounds like a choke problem.

Sorry for delay again. I did check to see if the choke was open all the way like described when it's warmed up and yes the choke is open, butterfly is straight up and down. So I do not think it is choke related anymore.

Just to add also, I did replace the O2 Sensor last night but that has had little impact. I also tried cleaning out some of the vacuum lines that I read about get commonly clogged up but that didn't help anything either. It's diffidently seeming like it is running rich to me, like I said it still has a pretty tough gas smell to it when running/idling. The idle however is pretty rock solid after it's been warmed up and running. Any tips on what to check next possibly on what could cause the carb to flood with more gas?

I'm thinking you have either a weak coil, or a leaky needle valve. You can test the coil fairly easily using the test described on p. 24-12 of the manual. If you have a leaky needle valve, that will require a full carb rebuild to correct. Consider that your "nuclear option." You want to exhaust every other possibility before doing it. The carbs are very complicated and finicky with lots and lots of dash pots, vacuum actuators, thermoswitches and other assorted goodies that like to crap out randomly and cause lots of headaches. The various goodies are listed on pp. 11-3 and 11-4 of the manual and there are tests for most all of them. Finding the exact problem is possible, but requires time to find. Spend the time to make sure that your problem isn't some $5 solenoid before shelling out to replace or rebuild the carb.

Also check out the Symptom to System Chart(s) on pp. 11-13 through 11-15. You will be able to match your symptoms to potential trouble areas and then flip to the pages that describe tests to find the problem.

If your troubleshooting points to the carb itself, then consider a Weber swap over a stock rebuild if that's smog legal in your area. We haven't had anyone complain about the Webers. They are much simpler and easier to tune and repair.

Check float level in the carb. For a good carb cleaning without rebuild, a couple things work well. Get some spray B-12 Chemtool or such solvent cleaner and after warm up and idle, spray a good dose directly into the float bowl via the diagonal vent tube on top of the carb. This gets a good solvent dose directly through the jets. Spray a bunch several times and rev the engine a few times to run it through all the jets.

For a fuel system cleaner added to the fuel, don't bother with solvent based stuff, use only high quality detergents that contain PEA. Redline SI-1 is really good here, I think Techron still has a good dose of PEA. A full dose in the tank and some spirited driving, after fully warmed up, the PEA will really help to blow out the carbon, valve deposits, etc.....

....shhh, knocking on mine that is running great with the original unopened carb.... I now just use a maintenance dose of SI-1 with each tank.

How's your gas mileage? that will clue how rich it is running.

Thanks for the tips. Sorry for the delays but due to my work situation I've on and off busy. I downloaded a copy of the manual and will hit it up to see if I can narrow my search down.

I'll give the B-12 a try and spray it where you said. I'l just trying to visualize the diagonal vent tube you are talking about but I think I know.

Gas mileage doesn't seem where it should be. It just seems like it is going through it faster than it should and I really only use it for going back and fourth to work which is 12 miles each day and local running here and there. I'm lucky if I hit 100 miles every week. I'll have to fill it again and keep track to get a more accurate reading. I thought the gas smell was from my exhaust hose that ran to the carb because it was pinched and broke open. I did replace it with a hose I found on the web via this forum which fit great but it did help somewhat but it still stinks pretty good like gas.