Problem 638 that you'll never likely experience on a fuel injected engine: Icing

[VTEC_Inside]

After replacing all the ignition bits and fixing a choke vacuum leak on my Accord I figured it was running as good as ever and ready for another winter, or so I thought.

When the temp drops around freezing and its raining, if I am driving along at steady speeds at or above 80kph, the throttle would start to feel heavy like you were towing a trailer. About the time that I'd notice this, it would start to stumble a bit. This would get progressively worse until the power loss was so severe that maintaining even 80kph was very difficult, and the stumbling would threaten to break an engine mount. Flooring it would result in smooth running, but drastically reduced acceleration.

Best part? By time I'd get it off the road to have a peak at my usual suspect, the choke plate, it would start to run normally again. Other times it would continue to run like shit with no obvious answer why. EVERY TIME, simply shutting it off and waiting a minute or two would result in it firing right back up and running like nothing ever happened.

Behold, carb icing. I'd suspected it as a possibility before but there were other little things wrong with it then that could have contributed so I wrongly dismissed it.

Cold damp intake air is freezing inside the primary venturi as it accelerates through it. It clogs the fuel jets, undoubtedly turning what should be a mist into a dribble.

Flooring it would open the secondary barrel which was till then unaffected, of course you can't do that forever.

Stopping the car would let the heat within the engine soak into the carb a bit more melting the ice and restoring proper running.

This all leads me back to yet another leaking diaphragm which opens a door ducting heated air from the top of the exhaust manifold into the intake. It works, but like the choke puller, probably not enough to prevent this condition. Its not possible to disassemble this one either so gotta order another.

[3.0L V6]

Maybe a completely rebuilt carb might be in order here?

[S204STi]

Maybe a completely rebuilt carb might be in order here?

No, he already identified the problem; the heat riser vent off of his exhaust isn't opening all the way, causing intake temps to fall to a level cold enough to permit icing.  Once he replaces that vacuum servo he should be fine.

[sportyaccordy]

I still think 4 barell Mikunis or Webers would be a better fix.

I am surprised you still have that car. Go Honda!

[Tave]

Accords weren't FI in '89?

[VTEC_Inside]

Maybe a completely rebuilt carb might be in order here?

The carb itself still seems to be in pretty good condition. I had it apart a couple years back to repair a fuel leak at the float adjustment screw.

[VTEC_Inside]

I still think 4 barell Mikunis or Webers would be a better fix.

I am surprised you still have that car. Go Honda!

There is a Weber (32/36 its referred to as, dunno if thats the model or just the venturi sizes, or what) that is a popular swap on the car. Apparently it does wonderful things for power output, but not much is mentioned about the emissions results.

I'd convert it to fuel injection before I'd hassle with mounting a different carb.

[VTEC_Inside]

Accords weren't FI in '89?

Its the last year they were available carb'd. The injected car models all ended in "-i".

There was a pretty significant change to the carburetors "systems" from '87 to '89, and I'm very surprised that it was cheaper at that point to sell the carb'd car versus just ditching it for the fuel injected version altogether.

[VTEC_Inside]

Isn't it great that I can still go into Honda and order new replacement parts for a 20yr old car?

Got the new hot air door actuator today and changed it when I got home. Its a tool-less job, just remove the line and twist. The old one no longer holds vacuum at all, not even slightly.

[Raza]

Canada's basically the wild west, right?  (That's a rhetorical question, of course it is)  Buy some dynamite, stuff your exhaust with it, run a fuse, light it, and watch the fireworks.