Choke not working 2 gen prelude1.8 EX dual carb

[AWH]

Hello,

The (automatic) choke on my 1985 2 gen 1.8 EX Prelude dual carburator is not working at all.
How should i troubleshoot? Where / what to start with,what would be a logical problem or often seen ?
Does anybody have any tips for me to get my choke working ?

Auke.

[Dr_Snooz]

Where / what to start with

Most people start by listing some symptoms. What is the car doing?

[2ndGenGuy]

Sort of wondering the same thing here... How do you know the chokes are not working?

[AWH]

Well.If the choke was working ,at a cold start in the winter like now,the rpm should start higher and later as the motor warms, come down to its normal rpm. Thats not the case,warm wheater starts up fine,but when cold it really struggles to keep going because the rpm gets too low. So i know the choke does not work,my question is why it not works and what can i look for to fix it ?

[Dr_Snooz]

You have to activate the choke by stepping the gas pedal to the floor one time before starting. Are you doing that? If so, then pull the lid off the air cleaner to make sure the choke is closing.

Still, we need symptoms. As in, "when cold the engine revs at 2000 RPM and never goes down."

[AWH]

I have really never ever heard of an automatic choke that you have to activate yourself...thats not really automatic then,is it ?Thats like having a manual chokepuller in the interiour like the really old cars.
But i will absolutely try your suggestion.
Symptomwise,like i said ,rpm is just too low with cold wheater.Like 400/500 rpm,nearly dying,gets normal as motor is warming.Warm wheater is just fine,about 900 rpm and stays there when motor gets warmer.

[AWH]

Well,you were absolutely right about activating the choke by putting the gaspedal to the floor once before you start ! I tried it and that works, starts up at about 1500 rpm so that is ok and thank you for telling me.
But then i still have an issue because normally the rpm should come down gradually to normal as the motor gets warmer,but in my case as i startup it now rpm's fine at 1500 with choke but as soon as i touch the gaspedeal to drive away,and then when i let go of it for shifting, the rpm is right back at 500 or so.In other words ,the choke cuts right off as i touch the gaspedal,and that should not be the case as the engine is not at its normal temperature yet. Any suspects for that ?

Thanks for that choketip,would never have found that on my own.:)

[Oldblueaccord]

Well,you were absolutely right about activating the choke by putting the gaspedal to the floor once before you start ! I tried it and that works, starts up at about 1500 rpm so that is ok and thank you for telling me.
But then i still have an issue because normally the rpm should come down gradually to normal as the motor gets warmer,but in my case as i startup it now rpm's fine at 1500 with choke but as soon as i touch the gaspedeal to drive away,and then when i let go of it for shifting, the rpm is right back at 500 or so.In other words ,the choke cuts right off as i touch the gaspedal,and that should not be the case as the engine is not at its normal temperature yet. Any suspects for that ?

Thanks for that choketip,would never have found that on my own.:)

Best thing to do to understand the choke operation is to totally remove the air cleaner and MANUALLY move the throttle linkage with your hand while looking at the carb.

You would want to do this with the motor off and ice cold like in the morning.

Once you get used to the operation you will be able to feel it thru the gas pedal and even by the click sound of the choke closing when you press down on the gas before you start.

The choke does come off when you use the gas pedal the first time. Allowing the engine to run 3-5 minutes with the choke ON will help when you goto drive and the choke comes off.

Carburetors are an imperfect device. That's why fuel injection became so popular.

[Dr_Snooz]

Thanks for that choketip,would never have found that on my own.:)

It's in your owner's manual...

[AWH]

Duh...

I do have a manual downloaded from Prelude Zone ,but i don't think that's an actual owners manual,more like a service manual.

But as i understand everything is working as should ,so that's a relief.Although i prefer a manual chokepuller as on my '86 Kawasaki GPz 1000 RX.
Anyhow,thank for thinking with me.Appreciate it.

[2ndGenGuy]

I don't know if the carbs work the same in the Preludes, but in the Accord there is a thermovalve that activates as the engine warms up. The thermovalve actually controls the high speed idle on the Accords. When they get old, they don't open and close as quickly, or can just get stuck open or closed... In the Accord it's more common for the engine to get stuck at high-rpms for longer than it should after it's warmed up. Perhaps your car is having the opposite problem.

Check your manual or vacuum diagrams for thermovalves. If you find it, follow the vacuum diagram to see where it leads.

I could be wrong, but I don't believe that the high-idle should kick down immediately after you start the engine. There should still be some warm up period after which the idle will kick down.

[AWH]

That is what i am saying. So the choke kicks in fine,but shuts down as soon as i touch my gas.I believe as you say ,that it should gradually shut down as the engine gets warmer until it is at normal working temperature and by then the choke should be off completely. So i will take a look at those thermovalves. Can you open these valves and clean them or something? Or can they just be replaced? And how can i tell if it is stuck?

[Hazwan]

I believe the service manual has the test procedure to check for the whole choke and fast idle system including the thermovalve. I believe theres also a wax case thing (sorry I dont remember the name for it) that would keep the idle up until the engine warms up.

Check your vacuum hoses. Maybe theyre rotted or disconnected or something.

[AWH]

Vacuum are all replaced with new,i am sure that is not the problem.
I cannot find an online repairmanual anywhere.I do have a servicemanual, but a lot of times i find the schedules unclear.I do not understand them,but that may just be my stupidity .

[Hazwan]

I should upload my saved copy of the service manuals pdf as most of the download links available are broken by now. Damn interwebs.

[AWH]

So,what's holding you back ?
Upload them.

[cygnus x-1]

Can you point out the broken links?

C|

Sent from my Nexus 5X using Tapatalk

[Dr_Snooz]

Probably from when we lost the Wiki. I saved what I could here: https://www.dropbox.com/sh/vtyhl48z5uftmt1/AAA0VFYqWyfZ35Nvudl0xk_Oa?dl=0

[Hazwan]

I believe it was the links on PP FAQ

Anyway here are the ones that I had saved a while back
https://drive.google.com/open?id=0B_ECWejctDJ5bVNTeG5MN1hzemc

This exact link has the choke stuff https://drive.google.com/open?id=0B_ECWejctDJ5b3pGaWEzemMtd2c

[AWH]

Some really good links there,thanks.

http://downloads.hondatech.info/Auto/Manuals/Prelude/Prelude%202/62SB000.pdf
http://downloads.hondatech.info/Auto/Manuals/Prelude/Prelude%202/62SB002.pdf
http://downloads.hondatech.info/Auto/Manuals/Prelude/Prelude%202/62SB021.pdf
http://downloads.hondatech.info/Auto/Manuals/Prelude/Prelude%202/62SB023.pdf

Cygnus ,those links above are on PreludeZone but are no longer working.