39 replies to this topic

[greenleafar]

ok. heres the downlow, or lowdown, whatever: i have a 87 honda crx dx. the carb has been giving me problems since i bought it about a month ago. it idles at around 2k rpm. that in itself isnt a extremely big problem, since its still drivable, albeit, probably pretty dangerous. i have tried adjusting the idle screw but nothing. well, just yesterday, and today too, whenever i rev it, it sticks higher and higher now. at one point, it was stuck at 3k. this was with it in nuetral mind you.

but heres the reall weird part. often times, after reving it up to about 5k or so, and i let off the gas, the rev's drop drastically without sticking, but way too low, like........0 rpms. the car just turns off. if i give it a little gas before it hits bottom, ittle stay on. sometimes, ittle turn on but wont stay on unless i give it some gas. the thing is, it does all of these things seemingly at random. this time itll stick, next time ittle just drop and turn off!!! im going crazy!!!

anybody have any ideas as to how to fix this? also, the previous owner did a rebuild on it.

[badpenny]

When you are adjusting the idle, are you allowing 15 to 20 seconds before doing any more adjusting? Because, It sounds to me, that you have a vacuum leak. You need to use some carb cleaner on the carburetor. I would start by backing out the idle screw 720 degrees from where it is now. And start over.

[greenleafar]

sounds like good advice. i just got some carb cleaner today. ive been reading up and i think your right, ive had some suspisions that it was a vacum leak. i read somewhere that a bad power steering line or something also causes a leak to the carb. i dont know, sounded kinda far fetched to me when i read that.

if it is a vacuum leak, how would i go about fixing that myself? keep in mind, im a total noob. plus, i probably wont have any of the necesarry tools, but i can get to some. i just need to be able to drive my car 20 minutes to get to them. thats where i need a freaking working carb!!!!! could i be able to drive it with a vacuum leak?

[zakats]

do you have the stock, in tact, vacuum mess or have you devac'd?

[greenleafar]

i havent done any of the kind of stuff to the car. i dont even know where that "vacuum mess" is.

i used the carb cleaner on it and didnt really help at all. i also tried messing with the idle screw and i couldnt get the car to go under 1.5k rpms without it shutting off. it would just sputter and die once it got to about that rev.

so, is it a vac leak then?

[zakats]

sounds like a vac leak to me

the vacuum mess: open your hood and look down, you will see 40+ vacuum hoses arranged in the most intricate clusterf**k known to man.

devac'ing is when you remove almost all of those vacuum hoses, a couple "black boxes", and some bs on the intake manifold in order to make things much simpler and void your car of some of that state-of-the-art 1984 technology that malfunctions over the 21+years of driving abuse. you then add some vacuum caps here and there, some block off plates if you want your intake manifold to look nice and puurdy, and about 15 minutes of time.
once you go there, there is pretty much no turning back. some side effects are: no idle/air conditioner boost (not that you really need it) but there is a pretty simple way to make it work again, your a/f ratio is said to richen a little bit but that has yet to be concluded scientifically, and you might accidentally get sucked into old hondas from the pleasure of your victory

[greenleafar]

ooohhhh sounds like something i would like to do!! but how hard is it to do all of that? remember, im not very mechanically inclined. is there any kind of write up about it with pictures that you know about? but would devac'ing solve my problem altogether? or would i still have that high idle and occasional shutting off?

[badpenny]

Ok, yes a devac would help, all you do, is remove all the brass tubes from around the carburetor, and on the carburetor, cap off all but 2 of the ports, these two ports are then connected with a "T" fitting and routed to the distributor. I will do a search for crxfanatic, he has pics of his devac. zakats had some, but for some reason has never posted them. Actually, annasa has recently done what you are looking at doing. Here is the link.

Devac writup link

[zakats]

I have no clue as to what happened to those pictures...

for some people it is rocket science but really it is pretty simple. you remove pretty much everything that isn't included on the pictures... once you have a good understanding of the way the car/engine is put together and what is really necessary, it should be very easy- just don't rush figuring it all out and researching. mentally plan everything you're about to do and think twice before acting keep that in mind an you'll do just fine, this is about as easy as doing a tune up.

[greenleafar]

OK, sounds good. but what is the purpose of removing all of that stuff? what is it actually meant to accomplish?

and what is the purpose of honda putting all of the stuff in in the first place if you can just remove it and the car runs fine?

badpenny, does "ok, yes a devac would help" mean that my problem would go away completely? or would i still have to replace the carb?

and how easy is it to mess this up and have everything ho to he ll? im pretty smart and i learn quickly, but ive never really worked on a car, and this is actually MY first car. my car as in "totally mine and not my parents who let me borrow it every now and to move around and what not"

also. would just replacing the carb do?

also, zakats, what does "no idle/air conditioner boost" actually mean?

sorry if its alot of questions. but i have to make sure i know what im getting into before hand.

thanks to all!!!

[badpenny]

Ok, yes a devac would help, means, that if your vac leak lies in one of the 44 vac lines, then yes, your problem would go away, you would still have to adjust the carb to keep it from running rich or lean. If you still have the problem after devac then your vac leak lies in the carb gasket plate.

[greenleafar]

oh, ok. so, the right thing to do would be to wait till i get a good carb, and if the problem still persists, that means that its not the carb thats bad and i should go ahead and do the devac right? well, im thinking ill end up doing the devac anyway, even if the new (old) carb works. i really appreciate all of the help guys. and that thread about the devac..... wow left me speechless. i love this place

[EuphoricBlue]

oh, ok. so, the right thing to do would be to wait till i get a good carb, and if the problem still persists, that means that its not the carb thats bad and i should go ahead and do the devac right? well, im thinking ill end up doing the devac anyway, even if the new (old) carb works. i really appreciate all of the help guys. and that thread about the devac..... wow left me speechless. i love this place

No, the right thing to do would be to systematically, one by one, replace every rubber vacuum line in your car with a new one. I know it's a lot of work, but hey, if you are just gonna be throwing parts at it, you might as well start with the cheep parts.

I mean, think about it... It's 20yo rubber and it will cost you like $10-20 to replace the lot of it. (yourself)

After you've done that, then we can start looking at carbs.


Also, I wouldn't recommend a devac on a USDM as your first project on the engine. You said to, "keep in mind, im a total noob." And people with considerable experience have had some headaches getting those devacs to work right for them. So start with some confidence builders. Go ahead and replace the lines, just do it one at a time and you'll be fine. You won't need anything special for this, just some time and dexterity.

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Note 1: A pair of pliers would help with twisting the vac lines before pulling, to break their seating. Old vac lines tend to stick to their seats, becoming hard to pull straight off, a quick twist breaks the bond.

Note 2: There may be a little vacuum manifold at the back of the carb attached with a short, (1.5" ish) thick (3/8-1/2" ID) vacuum line, replace that too. I've found leeks there on both my 1Gs and someone's 3G I've helped with. These leaks are hard to notice as the hole is usually on the bottom of this tube. I say there may be a manifold there because I've only worked on CDM carbs and am mentioning it incase USDM models have this manifold also.

[greenleafar]

ok. that makes quite a bit of sense. i did notice that quite a few people did have a little trouble getting their devac to work.

also, i forget to mention that i cant get past 40 mph on my car. i dont know if that changes anything, but maybe it helps some. i think i read something like that where someone had a similar problem, but im not sure. if i did, it was on this forum though.

also, where could i get the replacement vacuum lines? is it like a set or something?

Edited by greenleafar, 31 October 2008 - 05:10 PM.

[EuphoricBlue]

ok. that makes quite a bit of sense. i did notice that quite a few people did have a little trouble getting their devac to work.

also, i forget to mention that i cant get past 40 mph on my car. i dont know if that changes anything, but maybe it helps some. i think i read something like that where someone had a similar problem, but im not sure. if i did, it was on this forum though.

also, where could i get the replacement vacuum lines? is it like a set or something?

The vacuum line can be bought at any automotive store, it comes on a roll and is cut to length. I'm only guessing here, but for a stock USDM carb you might be looking at about 15-20 feet of vacuum lines.

As for your speed problem, it be caused by your secondary flap not opening again, could be cause by a vacuum leak, so we come back to just getting those out of the way first. The good news about throwing vacuum lines at it first, is that when you are done you can be sure those aren't gonna be your problem for the next 20 years

It's probably also a good idea to pick up new fuel filters with your vacuum line. Again, not a very hard job, just be careful with the fuel that will poor out. And this one could also cause speed issues.

Note: Our cars have 2 fuel filters, a small one in the engine bay, and a large one near the front of left side rear tire.

PS: You can see the locations of the filters at this link http://www.redpepper...1a/aag.png.html