Oil Drip (from bottom black tube)

[Lord Popgun]

That may cause--from the manual--Engine stalls, hard to start, rough idling, or engine cranks but won't start.

Plus I don't know what would happen when it is purged by the purge control solenoid.

[Townie_imp]

That may cause--from the manual--Engine stalls, hard to start, rough idling, or engine cranks but won't start.

Plus I don't know what would happen when it is purged by the purge control solenoid.

Popgun, what is this purging you're mentioning? Is it mentioned in the service manual?

Cause that's what it seems to be: some sort of purge that needs to happen occasionally. Just don't know what triggers it or what is actually purged.

[Lord Popgun]

Of course its in the manual. But the theory is not. You can google evaporative emission systems for more info as they all work kind of the same AFAIK

But, from the Honda Common Systems Manual, edited a bit:

Fuel vapor from the fuel tank is routed to the evaporative emission canister (EVAP canister) where it is absorbed and stored while the engine is stopped. When the engine is running and the evaporative emission purge control valve (EVAP purge control valve) is open, fuel vapor in the EVAP canister is drawn into the engine through the carburetor (ok, we don't have a carb so it most likely goes into the air plenum).

This is not new tech and has been around a long time. Cars have the same basic system.

Also, overfilling the tank can lead to saturation of the canister (charcoal) and that can cause problems, and drainage. Cars too...
Looking at the wiring diagram, the evap purge control valve is controlled by the ECM

[Townie_imp]

Thanks Popgun....I did a bit of reading, and learned something new today. Thanks!

It seems this dripping phenomena happens, but isn't overly common. On a CBR500 forum a rider described his drips as a "gooey amber muck"

I think you're right, that the evap canister might have become saturated. The big question is how. I don't let my bike sit for long (ride it every couple days), it's stored in the garage when not being used, and the day I saw this happen wasn't very hot. So I don't think there was a lot of vapor that could have accumulated in the evap canister.

I'll watch for it, if it happens again I'll bring it to the dealer.

Question: if the evap canister indeed became saturated (for whatever reason), does this mean it should be replaced, or could it eventually "dry out" on its own?

[Lord Popgun]

Townie,

That I do not know. I've seen on other bike boards where they dump out the can. Then I guess normal purging takes care of it. The way ours is positioned and plumbed, not much actual liquid could be in the can.

I guess you need to ask your service manager or tech at the dealer and see what they say. I'll ask mine sometime if I can remember.

There is a member on this board who is a bike mechanic. Maybe he could reply and might know exactly when the ECU does the purge.

I haven't seen anything drip out of my CB or the ST. Knock on wood!

[Riko_imp]

lol what seem to be a very easy explanation, the black tube is a "Fuel Tank Breather hose", has turned into more complex and unsure theories concerning the black tube

I did fuel my bike, it had about 3,1 litres left, and the range should be around 59km, the milage was on that moment 302km or so.
But the bike started to judder....so I decided to tank.

I managed to tank around 20L, on a tank capacity of 17.5 litres
Could be the exces fuel was dripping from that hose? dunno, didnt notice it, I stood on the other side of the bike.

Anyway, after the ride home, spirited riding, I noticed 2 drops on the ground coming from that tube, and even a little bit of smoke coming out of it....
It did smell like gasoline.

This is due to overfilling the gastank, I assume?

[flynrider]

Yes, you are correct. There is a tank vent hose that runs to the evap canister. Normally, this will carry fuel vapors to the canister. If you overfill your tank, actual liquid fuel will migrate down the hose to the canister and will eventually come out of the canister drain hose.

[Riko_imp]

Aaight. I rest assure!


Thx man!