- This topic has 21 replies, 3 voices, and was last updated 7 years, 11 months ago by
.
-
Topic
-
So my car, a 1984 Honda Accord, has been having the following problems lately:
- Hesitates/stumbles on acceleration
- Misfires under load
- Will not stay running when cold/humid, stalls within seconds
I’ve ruled out problems with weak spark or the ignition system. I’ve replaced the ignition coil, spark plugs (OK condition), spark plug wires, distributor (was leaking oil internally), distributor cap, air filter, and there are no vacuum leaks. Battery and alternator were tested and determined to be OK. The ignition timing is likely retarded (incompetent mechanic’s fault) since the vehicle has had poor acceleration/lack of power ever since the distributor was replaced (month ago). RPM at idle is usually 800, although sometimes it will randomly be higher when stopped at a red light (bouncing between 1100 and 1500), at which time I have to be very careful when I accelerate and it fixes itself a few seconds later and stabilizes. It also idles much higher (2500 RPM) once in a blue moon when I start the car, but settles back down to normal after driving for a couple of minutes. Like I said, no vacuum leaks.
I no longer drive the car at night at all, since it always does one of the following: 1) Dies within seconds of starting, then becomes very difficult to start again, 2) Runs OK until you get about two blocks away, then dies and repeats #1 over and over again – have to get a tow, or 3) Runs OK until you stop the car at a location within a short distance of where you started it (i.e. gas station), then when you start it again, either #1 or #2 will occur. This also happens if it is very humid or raining. However it will NOT happen at all if it’s a warm, sunny dry day. I can drive it during the day for hours in 100F and heavy traffic and it won’t stall.
^ Note that the car did not have this problem with stalling until about three months ago. I was told by a mechanic that the cold start enrichment circuit in the carburetor may be malfunctioning and causing misfires. This page about my Keihin carburetor has been informative as well.I don’t think the problem is a bad fuel pump. If it was that, it would be stalling all the time regardless of weather or time of day. I’m going to replace the fuel filters (yes, there are two on my car) later this week when they come in the mail, just as a precaution. I’ve called multiple shops specializing in carburetors in my area, and I found one that will rebuild it for $250 (or just $130 if I take the carb out myself). Other shops wanted to charge me double that for the very same services. I don’t know what else it could be at this point. I’ve checked the throttle shafts, choke plate and butterfly valves – they are clean. The accelerator pump squirts out a decent stream of fuel into one of the bores when I press down on it with my finger. The fuel level in both fuel bowls are right where they should be. On another note, I found the previous owner tells me that the carburetor was rebuilt in 2010 and I have the receipt as proof. That was about 40,000 miles ago (and if you’re curious, the car has only 121,000 miles on it). Does it really need another rebuilding already? Or is it something else?
-
Replies
-
If the ignition components are good that would leave fuel and compression.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
A 32 year old carb should be rebuilt, regardless of what the reasons for your performance issues are. Honestly, you’re probably better off getting a brand new replacement carb, if available. A wear point and source of vacuum leaks on all old carbs is where the throttle shaft passes through and rotates within the carb base casting, which isn’t shown on the page you linked. The holes for the throttle shaft become enlarged and go out of round over time, and carb kits don’t fix this issue. If you’re forced into using the original carb, there might still be a few places that will sleeve the holes and hone to size, but it’ll probably involve shipping the carb to wherever.
Having said all that, I’d still be looking at the ignition system, seeing as how your issues seem to be moisture-related. Carbs generally don’t care about humidity, except in the case of carb icing, which shouldn’t be an issue at this time of year.
[quote=”Evil-i” post=166950]A 32 year old carb should be rebuilt, regardless of what the reasons for your performance issues are. Honestly, you’re probably better off getting a brand new replacement carb, if available. A wear point and source of vacuum leaks on all old carbs is where the throttle shaft passes through and rotates within the carb base casting, which isn’t shown on the page you linked. The holes for the throttle shaft become enlarged and go out of round over time, and carb kits don’t fix this issue. If you’re forced into using the original carb, there might still be a few places that will sleeve the holes and hone to size, but it’ll probably involve shipping the carb to wherever.
Having said all that, I’d still be looking at the ignition system, seeing as how your issues seem to be moisture-related. Carbs generally don’t care about humidity, except in the case of carb icing, which shouldn’t be an issue at this time of year.[/quote]
I’d like to avoid getting a new carb if possible. Believe it or not, it actually managed to pass smog here in California back in March. Getting a new carburetor would not only cost me a lot more $$$ that I don’t have, but it would also be more difficult to tune correctly to my car and get it to pass smog next year. So I’d like to keep it original like many other things on the car – but if the throttle shafts are worn like you say, how can I test that? Would they just wiggle around more or what?
And about the ignition system, I’ve replaced just about everything there is to be replaced I think. Could it be a problem with a mechanism in the air cleaner assembly? My car also has a control box, which has a tiny air filter inside of it – that thing is absolutely filthy, and I have no idea what it’s called nor can I find replacements for it anywhere online. That air filter is also connected via vacuum lines to the power valve on the carburetor, among other things. I also tested the EGR valve a week ago and it holds vacuum properly, works fine.
Here is the dirty mini-air filter in question:
I opened the control box, unscrewed the mini air filter and disconnected the two vacuum lines from it and started the car. It would barely start at all, and once it did, it idled very poorly. Acceleration was still normal though, oddly enough. I even put the tips of my fingers on the ends of the two vacuum lines – felt suction from one of them, nothing from the other. That mini air filter is so brittle that it was practically crunching into pieces when I held it. It’s still intact, I put it back in the car and started her up again and the idle was back to normal, the car ran just as it was before I removed the mini air filter.
My car does have an air control diaphragm on the air cleaner intake duct. It controls a “hot air door” for cold-starting. Could the air control diaphragm be defective?
If i’m being honest. Its hard to diagnose this type of problem over the internet.
Thats why we recommend the rebuild to eliminate the seals and worn parts.I had the carburetor rebuilt today for $243. Took a few hours, I mainly just walked around Downtown while they did it. Once they were finished, the mechanic and I talked for a while – he said the carburetor had a damaged power valve, and he replaced it along with the accelerator pump. He said it was causing the engine to run rich as well. I drove the car back home (it’s 106F today and traffic was pretty bad) and the car is running the best it’s ever run since I bought it. Very smooth acceleration, better response from the accelerator pedal. All stumbling/hesitation is gone completely, it drives like a newer car now. 🙂
Now I took the air control diaphragm off the air intake duct after I got home. Unfortunately it doesn’t look like it can be disassembled, but I’m going to play with it and see if I can confirm a leak. We’re in a heat wave right now so it’s staying very warm at night – my car might actually stay running even if the stalling problem is still apparent since it’s not dropping below 70F. 😆Okay, well after running almost like new for a few days – the car is stalling again, severely (just in the last 24 hours). It also acts very odd within the first two minutes of starting (erratic RPM, stumbling, rough idle, missing at idle) but then all of those issues seem to go away all at once after driving for a couple of minutes. This morning the car stalled on me, but I simply turned it off and turned it on again and the car was fine. This evening, I had to leave my car in a nearby parking lot because it would not stay running when I was out running a couple of errands. It’s doing the same old thing again. I knew I was right to be skeptical…
The carburetor is under warranty, so I’m going to take it back to the shop tomorrow (if the car even runs at all). I think the engine is flooding out again, it acts like it anyway. Could a new power valve have already failed?
[quote=”college man” post=167659]Check that your choke plate is opening.[/quote]
I walked down to my car this morning, popped the hood, removed the air cleaner assembly and poked around the carburetor. The choke seemed to be operating fine. After checking everything else, I couldn’t find anything unusual and so I turned the key in the ignition. Cranked forever but would not start. So I gave it a tiny bit of gas, then tried again – started immediately, and idled surprisingly fine. The car was stumbling on acceleration for the first minute of driving again, but eventually it went away and I got the car home safely. The RPM was perfectly normal the whole drive, unlike yesterday.
Yesterday evening when the car was giving me problems, it would idle extremely high for a couple of seconds (as though I was flooring the gas pedal) before dying. When I would wait a few minutes then trying again, it would idle normally, but then sputter out and die at the moment I gave it any gas.
I watched videos on how to unflood a supposedly flooded engine last night, so I was prepared to do that this morning if the car was still quitting on me. Of course, I can’t confirm that the engine was flooded. I still don’t know whether it was running too lean or too rich. Either way, my fuel filters finally came in the mail a couple of days ago, so I’ll swap them out when I have time.
Car left me stranded again last night, had to push it to a safe spot 1/4 mile down the road onto a side street. It just refuses to stay running after the sun goes down. This car is my only means of transportation, and while I’m broke and at the bottom of the economic ladder – I refuse to junk this car.
What else could be causing this mysterious, persistent problem?
see if this helps.
- You must be logged in to reply to this topic.