civic ed3 d15b4 twin carbs
MKR Adelaide
Good luck with the Techron 5000 treatment. A run up to Claire should get the Techron where it can dissolve precipitates. Of course there are numerous problems that can also affect the carbies. Air leaks in the vacuum lines is a number one issue, also the dubious wax operated choke control is another along with a little regarded fuel pressure control valve situated in the intake fuel line between the crank operated fuel pump and the carby inlet. Once carburetors have been disassembled outside of a very professional rebuild and refit specialist who without exception discards absolutely all previous gaskets, O rings, jets and anything else supplied in a rebuild kit and who re tightens all bolts to torque specs, then I would be inclined to start all over again, assuming previous sloppy workmanship. I carried out a sloppy rebuild and refit on an older 1980 Accord some years ago. Similar symptoms but a painstaking total rebuild of the carby solved the idle and low speed stall. It turned out to be a warped manifold carby flange out of specs for the gasket. Made a new gasket from thicker gasket material, squirted sealant all over and around joint. Worked!.
civic ed3 d15b4 dual carbs
MKRS Adelaide
Have you changed the Ryco Z616 fuel filter located in the rear offside wheel arch? Low pressure fuel supply can effect idle. The choke thermowax valve cannot be dismantled nor checked for operation other than by vacuum testing or noting the opener rod movement. Hot water at correct engine temperature melts the wax pellet, a sticky choke blade in the carby throat will cause over rich mixture thus ensuing engine stalling. Vacuum lines are a problem. Apart from blockages in the carby fuel and air jets and passageways from precipitates, hopefully not grit or sediment, an entirely different matter, over rich mixture causes most of your problems as well. Keep us posted on outcomes, especially the well needed trip to Clare for driver repair. Bobval
civic ed3 d15b4 dual carbs
MKRS
Just been viewing stacks of old posts on Keihin 2 barrel DA76B carbs, mostly USA crap dated up to 1997. The USA ceased the Keihin carbs after 1987. The problem we both suffered was so common that most people scrapped the Keihins for Webbers due to complexity and cost of repair. It seems 90% of the cause was located within the CV valve, certainly the wax pellet choke control, vacuum leaks and of course contaminated fuel jets and airways. Even in the USA in the early 90's carburetor overhaul was being quoted around $500, but a firm in Florida would overhaul your carby for around $350. Only USA customers. Civics and Accords that used Keihin were being dumped as unreliable and became student giveaways. One must presume that the Techron 5000 solution did not exist and people were focused on physical disassembly without being aware of the actual cause or causes of carby failure. The Keihin is a nightmare to service or understand the principle of operation, CVCC altered all we understood about standard carburetors. Fix it by Techron 5000, a full vacuum check, fuel filter change, correct operation of the choke opener, a fuel mixture adjustment ( only possible by a qualified workshop) and if all fails, dump it as no longer economic to repair. Bobval
civic ed3 d15b4 dual carb
MKRS
I committed the fatal and unforgivable crime of assuming that the only reference I could locate for the Keihin dual carb was merely two of the single double barrel carbs constructed together. Crap! completely different carbs and never released in the USA, at least not the version we have for the Australian only marketed, ED3 D15B4 Civic GL. In fact our GL differs from all other markets. Seems we got a 9.2:1 compression and the English version was a 9.7:1, it was a D15B variation. The ED3 (ED is European right hand drive designation, Japan had the JDM version also running higher compressions.) was manufactured from late 1987 until final batch for OZ in late 1991. It is referred to as the Civic 1987-1991. Mine is a Japanese manufactured October 1990 model, OZ compliance plated January 1991, sold May 1991. It appears that no workshop manual has ever been released for the Australian version, Honda must have had confidential copies to monopolize service. I have to go by the English Civic GL which was called a Contessa or something similar. There are differences. So what seems the same is actually different, not only that but Honda did alter specifications throughout the production run, my GL might be different to your GL. As you stated yours is a two door, Honda Civic GLs were only ever made as 4 door cars. The hatch version is different in specifications. However surely the D15B4 dual Keihin carburetor engine is the same, Maybe? I can feel the fuel flow change at 1850 RPM from a cold start that is the revs that the choke holds the idle accelerator at until choke closure commences and very quickly drops to idle at 850 RPM once warm. The heel and toe dance was common prior to Techron 5000 due to failure to idle as per blocked idle jets, incorrect air pressure to activate strange fuel ratios and all because the choke vacuum operated control and idle wax pellet, which must work in conjuction and one seems to operate the other, which is which? I do not know. Once Techron 5000 did it's stuff and cleared jets, airways, fuel passages, the common cold and whatever else depends on the correct operation of the carburetor, things improved from zero to 100% over nearly three months. It all depends on the extent of blockage, where and of what cause. As I stated, a mechanical fault or actual grit contamination is outside of Techron 5000 to eradicate. My contamination was pretty bad, a lot of precipitate dissolving was required in tiny jets to get any sort of operation, no revs below about 1800 RPM, obviously the high speed jet and fuel starvation over 3000RPM. I actually had no idle jets operational at all.
Seeing as you have a spare twin carburetor set, the gasket, O ring kit is $150, have them rebuilt by a professional, making sure all kit items are installed. As you will do the re bolt on to the manifold and re connect all the hoses, control rods, throttle cable etc make sure you have a new manifold gasket, the old one will be US. Flooding becomes a problem if the idle jet is US, ends result, stalling. The car has become a project, try and enthuse your daughter with the rebuild, she will gain knowledge usefull in many things, one being a rational approach to problem solving.
Good luck Bobval
civic ed3 d15b4 dual carb
MKRS
I committed the fatal and unforgivable crime of assuming that the only reference I could locate for the Keihin dual carb was merely two of the single double barrel carbs constructed together. Crap! completely different carbs and never released in the USA, at least not the version we have for the Australian only marketed, ED3 D15B4 Civic GL. In fact our GL differs from all other markets. Seems we got a 9.2:1 compression and the English version was a 9.7:1, it was a D15B variation. The ED3 (ED is European right hand drive designation, Japan had the JDM version also running higher compressions.) was manufactured from late 1987 until final batch for OZ in late 1991. It is referred to as the Civic 1987-1991. Mine is a Japanese manufactured October 1990 model, OZ compliance plated January 1991, sold May 1991. It appears that no workshop manual has ever been released for the Australian version, Honda must have had confidential copies to monopolize service. I have to go by the English Civic GL which was called a Contessa or something similar. There are differences. So what seems the same is actually different, not only that but Honda did alter specifications throughout the production run, my GL might be different to your GL. As you stated yours is a two door, Honda Civic GLs were only ever made as 4 door cars. The hatch version is different in specifications. However surely the D15B4 dual Keihin carburetor engine is the same, Maybe? I can feel the fuel flow change at 1850 RPM from a cold start that is the revs that the choke holds the idle accelerator at until choke closure commences and very quickly drops to idle at 850 RPM once warm. The heel and toe dance was common prior to Techron 5000 due to failure to idle as per blocked idle jets, incorrect air pressure to activate strange fuel ratios and all because the choke vacuum operated control and idle wax pellet, which must work in conjuction and one seems to operate the other, which is which? I do not know. Once Techron 5000 did it's stuff and cleared jets, airways, fuel passages, the common cold and whatever else depends on the correct operation of the carburetor, things improved from zero to 100% over nearly three months. It all depends on the extent of blockage, where and of what cause. As I stated, a mechanical fault or actual grit contamination is outside of Techron 5000 to eradicate. My contamination was pretty bad, a lot of precipitate dissolving was required in tiny jets to get any sort of operation, no revs below about 1800 RPM, obviously the high speed jet and fuel starvation over 3000RPM. I actually had no idle jets operational at all.
Seeing as you have a spare twin carburetor set, the gasket, O ring kit is $150, have them rebuilt by a professional, making sure all kit items are installed. As you will do the re bolt on to the manifold and re connect all the hoses, control rods, throttle cable etc make sure you have a new manifold gasket, the old one will be US. Flooding becomes a problem if the idle jet is US, ends result, stalling. The car has become a project, try and enthuse your daughter with the rebuild, she will gain knowledge usefull in many things, one being a rational approach to problem solving.
Good luck Bobval
