Air & fuel/vacuum problem?

[1986AccordLX]

Hello, I have a 1986 Accord LX w/A20A1 engine with 190,000 miles. My dad and I recently replaced the head on it, and after reassembling the intake to the head and the carb to the intake, we have had trouble with fuel delivery it seems.

Before reinstalling the carb, I disassembled it and cleaned it out with carb cleaner, making sure no rubber parts or diaphragms were contaminated. I then bought that $30 rebuild kit from O'Reillys Auto Parts and put new gaskets, o-rings, and a diaphragm (I think for the accelerator pump) in. I also installed a new intake to EFE plate gasket, so I think that's alright. We have hooked up all of the vacuum lines we know of which were disconnected, and double-checked to make sure they matched-up alright. As far as we know, they are in the right places.

We were able to start the car and keep it running, but it idled poorly. It acts as if it is always running too lean, since I can make it run very smoothly (and speed it up) if I place my hand partially over the primary bore of the carb or close the choke a bit.

I made sure the float level is centered in the glass window, and I have even tried to adjust the A/F mixture, which had little, if any effect on the way it runs. I can adjust it to the leanest it will go to, all the way in, and it will still run. I believe this is abnormal?

The gas is fresh, and as far as we know the vacuum hoses are hooked up correctly... although it may be easiest to take some pictures and show you where each of them are going.

One last thing which we still need to do is time the car, but I know there is definitely a problem with the amount of fuel getting to the engine since I can make it run better with a restriction of airflow. I have the idle around 1100, but when I partially cover the primary bore it goes up about 600 or 700 rpms. I also have checked the venturies to see if they were loose... I replaced the o-ring for the primary venturi.

I've looked around on this forum quite a bit so far and foumd it very helpful, but I am still at a loss for what this could be. Sounds like vacuum or internal carb problems to me, but it's hard to say. We've yet to perform a vacuum test on it. The engine backfires out the exhaust until the primary bore is partially covered, then it smooths out and misses cannot be heard.

Any ideas? Thank you very much for any help you may have.

[VTEC_Inside]

What condition is the intake manifold gasket in? Did you replace it too?

[1986AccordLX]

We scraped off the old intake manifold to head gasket as well as the intake to EFE gasket. We still need to determine if there are vacuum leaks coming from there though. We're going to perform a vacuum test on the engine next.

[VTEC_Inside]

Hopefully you find your leak.

I've only had two siginificant vacuum leaks on mine. One was a hose concealed by the airbox that had come off. The other was the intake manifold gasket.

The hose was worse though. Thing almost died at idle.

[1986AccordLX]

Thanks, which hose was it causing the problem, the #6 one (Ithink?) to that valve on the airbox? That was loose on mine at first and, needless to say, it wouldn't run at idle at all ...

I can definitely see where that and the intake manifold gasket could cause problems, I at least have been able to rule those ones out.


I actually took apart the carb one more time and only found one of the vacuum hoses on the bottom back had a small tear in it, which, after replacing, didn't seem to have much effect on it.

Unfortunately, I haven't checked for vacuum leaks using the vac gauge we have yet, but I've read the thread in the FAQs on it and printed it off. The only thing I'm confused with is which port to hook the gauge up to... either # 6 or 20 can be used, yes?

https://www.3geez.com/forum/attachmen...achmentid=4554

I am going to go over the vacuum line routing once again to make sure nothing's routed incorrectly, though. It runs now, but dies making right turns and when the right turn signal is turned on, it blows the gauges fuse under the fuse box :\... but that will be next I guess.

Thanks for your reply :].

[VTEC_Inside]

Both of the leaks I had were discovered by the mechanic at the dealer. I'm not entirely sure which hose it was that had come off.

That was before I said to hell with the dealer for diagnosing this type of thing. The last straw was a choke issue that I paid them $200 to diagnose and ended up solving the problem myself with help from the folks here and the service manual.

You mention carb at a shop these days and they want to know what diet you're on.

[1986AccordLX]

At least you found out what was causing the problems, but the price is ridiculous... I guess you can't expect much else from a lot of shops out there. That's definitely what I'm trying right now... to find out the problem without having to pay an arm and a leg for the diagnosis from a 'professional.' Everyone on here actually owns a third generation and that alone allows for more first-hand know-how, plus being able to share common problems and ideas for these cars, so this is definitely where to start and finish if the problem can be fixed by the owner.

Hee hee, I don't doubt it one bit, the word carb associated with anything but old domestics seems very ominous by itself... most seem to shy away if they don't own a car with one, especially with the vacuum and electronic components. I guess it's preserving/owning a bit of automotive history, although it may not be convenient .

As of now I'm draining out the old power steering fluid, because I didn't put in the Honda appropriate type... whoops .
As far as the vacuum thing goes, I did notice my thermovalves (I think that's what they are) on the back of the intake are opposite of what the manual shows... I don't know where to start there. I need to get a vacuum gauge that works and conduct the vacuum test still, just have had trouble with the car in general.

When my sister acquired it in 1997-ish from a shady used car dealership, the car had about 140,000 miles on it. When we took it to a shop when the muffler was shot, they noticed the floor pan had been welded in two back by the rear seats in front of the gas tank. Apparently the car had been in a pretty bad wreck or something and needed to be joined there... but the frame doesn't appear to be totally split... just the floorpan. There was a sealant on top of the weld and they must have undercoated it at the dealership to help hide that bit of a flaw, but almost ten years later, here it sits, with only 190,000 miles on the 2.0 engine and four speed auto transmission, and the body is going to waste. I noticed the infamous rust bubbles forming under the paint around the rear wheel well, and started to dig away the rust... a gentle probing of a screwdriver got rid of the major rust, and left many holes around the wheel well, which wasn't too bad. Then, I proceeded to the rocker panels and the edge of the floor pan, where I could dig out rust to my heart's content... the edges of the floorpan, especially around the weld, had rusted enough for me to be able to get a screwdriver up through the floor and under the carpet... wonderful. I then noticed the fuel filler neck, from the upper weld up to the cap, was rusted, so I basically have a hole for fuel supply contamination. Also, part of the rear portion of frame by the rear right shock tower is rusted through, but just a hole in the bottom... so I'm now wondering how structurally safe it is. Finally, I have rust holes along the trunk floor above the little metal supports close to the inside of the rear quarter panels, behind the plastic covers.

I may be better off pulling the engine and tranny and the computer stuff and seeing if I can swap it into another 3rd gen. Accord LX, but perhaps I can repair this one. Whatever's compatible and the cheapest is what I'm looking for I guess. I would hate to see this car go, but maybe its heart can live on...

[1986AccordLX]

I looked into the engine again today and finally figured out my problem, it was a failed primary slow mixture cut-off solenoid valve. All it took was a simple check and sure enough, the plunger thingy didn't retract when voltage was supplied, and power was getting to the solenoid, so today I'll be checking around for one I suppose. I temporarily taped the plunger all the way down and reinstalled it in the carb... it runs like new, even though I haven't fine-tuned ignition or fuel mixture. After all these months that was the problem, I lerned the hard way I guess, but finally it runs without a lean miss and actually gets enough fuel !

Sorry about that double post!

[A20A1]

LOL, I was about to suggest the solenoid then I read your final post... you sure write a lot

[1986AccordLX]

Lol thanks anyway, it feels so nice to be able to get the car to run right after so long! I could probably be a lot more brief and still get the point across, I know I like to write a lot but don't like to read a lot !

By the way I wouldn't have even been able to identify those parts on the carb without this site and the awesome information from you guys, I was about ready to give up on that car until I found this site... I read around and it gave me some newfound hope. Now I know it did pay off to do some testing here and there, pretty simple solution after all. I've still got a long way to go on the rest of the car though... I have to make some choices about that now, but the engine works like new. Thanks!