prelude_girl

Hi all,

New member and so glad to find this forum.

I have a 1982 Prelude for which I need help diagnosing an engine problem.

Here is what I think is the critical history and symptoms:

Symptoms:

About a month ago I stopped to get a soda from a drive through restaurant. I parked in the parking lot and stopped the motor to drink it and check my emails on my smart phone. I probably was there about 5-10 minutes. I tried to start the car and it had a very difficult time starting. The symptoms were reminiscent of being flooded but I had never had this happen before. The day was not hot and not humid and I had parked in the shade. I was eventually able to get it going but its idle was very weak (loping) and not steady. When I tried to accelerate it (in neutral) the throttle response was very weak and did not go up as high as I would have expected.

I tried to drive around the parking lot and barely could keep it going under load. At this point I decided to try to drive home (about 2 miles). I got it on a side street but immediately realized it would not go very far and I would be safety hazard. I then parked it on the street so that if needed I could get it towed.

The next day while waiting for the tow truck I tried it start it again and there was no change in the symptoms. I had the car towed home as neither of the two local shops known for their expertise on carburetored Hondas wanted to mess with it. After being gone for a week of travel I tried starting it again and the symptoms had not changed.

Recent History:
The week before the failure I had replaced the fuel pump and both fuel filters (between the tank and the pump and just upstream from the carburetor). This was done because the month before at highway speeds (greater than 65 miles per hour) the motor would die as if starved for fuel. I found that as long as I kept it at about 60 mph I could keep it running and was able to drive the 120 miles home without incident. These symptoms had been getting worse over many months. After replacing the pump the symptoms went away and the car drove beautifully.

This last few days I've had a chance to look at it again and was able to check the following things. I was able to get it started one more time with the same symptoms. This time I also tried it with the choke plate force open. When the screwdriver forcing the choke plate open fell out out it ran a little rougher (in addition to the very rough, loping idle it already was experiencing).

When I checked the original plugs that had been in there for quite a while, they were all covered with carbon and the middle two (cylinders 2 and 3) were wet with gasoline.

I put new plugs in and the symptoms did not change except for them not having a chance to get covered with carbon.

Other checks so far:

• I have checked the fuel pump output, both pressure and volume and found it passed (3 p.s.i. and 24 oz/35 seconds into a container). I fuel pump cut out relay is working as expected as best as I can test using my Haynes repair manual as a guide.
• The accelerator pump works (checked by seeing fuel squirt into the carb)
• An initial inspection of the vacuum hoses to the carburetor did not show any visual problems. I was able to draw a vacuum on a couple of the diaphragms except the one for the choke which leaked a little. (I've heard there can be tears in the diaphragms that can cause a carburetor to fail.)
• The ignition coil and spark plug wires checked out as fine (I measured the resistance of the primary and secondary coils and resistance of the wires and they met spec.)
• The fuel levels are correct in the fuel bowls (the rear one is spot on and the level in the front (secondary?) one is half way between the dot on the sight glass and the top of the sight glass).
• The cam timing is correct and the belt has not slipped. (I took off the valve cover and with the motor at TDC the cam sprocket was correctly aligned.)
• The EGR valved checked out fine. It is neither stuck open or closed and opens when vacuum is applied to the diaphragm.

What puzzles me is how suddenly the performance deteriorated. Before my stop it was running fine and when I tried to restart it I could bare keep itself going.

I'm to the point of having the carburetor rebuilt. Before I go down that road and spend that money, I am wondering if any of you had other suggestions.


Thanks,

Christine

alex63

Did you recently just put fuel into the car before the problem started?
You could have water in your fuel? You could check this by pumping some fuel into a container and seeing whether you get a layer of water sitting on petrol.

prelude_girl

Thanks for the idea.

When I did the fuel pump check (pressure and flow rate) I did not see any water in the gas so I don't think that is it.

Christine

2ndGenGuy

It almost sounds like a choke issue... is it opening up after the car warms up? But if that were the case, it would be running fine when it was cold... You MIGHT still try another coil if you can borrow one from another car, or from a friend. I am pretty sure a bad coil can still pass the resistance check. Same with the plug wires. I had some bad ones on a race car that was running like crap, they passed the resistance check, but replacing them wound up solving my problem anyways. I dunno why.

prelude_girl

I've tried starting it with the choke forced open and not and opening it helps just a little. On the few times I could get it to start, it would still be lopping and struggling to keep itself going, always on the verge of dying.

However, what you said about the coil is intriguing. I do not like to buy parts just to test them but the local parts store has them for $20. That is much cheaper than having the carb rebuilt for $250 to $300!

Thanks!

Christine

prelude_girl

Final Update: In case anyone finds this thread, I thought I'd post a final message with what I found out.

Short answer: Having the carb rebuilt fixed the problem.

Long answer: The auxiliary fuel bowl inlet valve was probably stuck open. The carb shop guy said it took three different tries with three different floats to get the valve to close. He never could see what it was that was binding. Fortunately he had a proper flow bench that allowed him to pressurize the fuel lines to check. I got a chance to see the innards of another identical carb and I could see that it is very complicated. I am glad I did not attempt the rebuild.

The carb guy showed me all of the worn out parts so I'm glad it had a good going through. As far as he could tell it was the first time the carb had been opened since it was assembled in 1982.

A note on the vacuum lines. I was very glad I took MANY pictures of the vacuum lines that went to the carburetor to help me get them back in the right places. The diagram on the underside of the hood is not good enough to do this. I wish I had one one more thing though. It would have have been easier if I had marked which of the lines I had taken off so that I would have had a check list of the vacuum lines I had to put back on. There were so many that I actually almost forgot a couple of them.

If any of you do what I had to do, be sure to get some golf tees to block off any of the vacuum lines to the air-breather snorkel. When I was checking the mixture settings, not having these lines (2) temporarily plugged made it run very rough.

Lesson learned? Carbs can fail suddenly, not just gradually. Mine did. Before I stopped for 5 minutes to drink my soda it was running fine. When I went to restart, it was barely able to keep itself going.

Now I hope for 30 more years and another 200k miles from the car! ;-)

Best

Christine

2ndGenGuy

Wow awesome! Thanks for the final update. Not enough people do this. Awesome to hear that you got it fixed and that it's running awesome! Should run awesome for a long time now that you got the most problematic part of the car totally overhauled. And cool that you found someone who really knows his ****!

miles2go

Hi Christine,

Glad your car is running right again. Could you let me know how much the carb rebuild was and where the rebuild was done? I need to send them a carb to get rebuilt.

Thanks,
Andrew.

prelude_girl

Andrew,

I'd be happy to share.

The shop I used was Nowlan's Carburetor, 433 E Sprague Ave, Spokane, WA 99202, (509) 624-8524.

The price for the rebuild was $350 before sales tax.

I had asked around my hometown (Moscow ID) but no one wanted to work on it. One of the people initially quoted $250 but later declined to work on it. In the end the guy in Spokane ended up being better equipped and more of an expert than anyone else I could find within driving distance.

I've since put 400 miles on the car since the rebuild and everything is running fine.

The carb guy suggested I use nothing but ethanol-free gas from now on. (We fortunately have this in town, for a price.) He said that this will keep the rubber parts from deteriorating. I've since learned from a mechanic who specializes in imports that another reason to not use gasoline with ethanol is that ethanol gas burns hotter and that can mess with how the motor operates.

Three more thoughts to leave you and anyone else who finds this thread:

1) The owner of Nowlan's prefers it if a rebuild of the carburetor has not been attempted. He showed me an identical one to mine that he was not able to rebuild (rescue?) because many of the threads had been stripped by the owner attempting to rebuild it on their own. These are complicated carburetors, it is best to let a pro do it if you have not rebuilt one of these before.

2) When you install the carburetor, be warned that it is really hard to reach the mixture screw. I'd suggest testing any tool you plan to use to adjust it before you install the carb so that you know you will be able to reach the screw once it is installed.

3) Float levels are important and must be set exactly!

Good Luck!!

Christine

P.S. I've attached a picture of my car to the post.

I also posted in my photo directory (Prelude_girl's '82 Prelude) a picture of the float levels before the rebuilding showing the aux bowl being over full.

miles2go

Thank you. Nice Prelude. Classic!

letank

The issue with ethanol is that it throws the mixture air-gas lean, and so the engine runs hotter. Unfortunately in cars that do not have computer controlled real time oxygen sensor feedback, it burns leaner and hotter. There is really no way for our carb to make an adjustement for the OEM carb on the whole rpm range. You can tweak the idle mixture screw but this is only good for idle and slightly above idle. There is no available jets to swap for performance. So for the counties not subjected to strict smog check, a carburetor swap is the way to go, not necessarily an easy way as most swap are using the weber with various results.