EEC issues, fuel drip from Active Carbon Can

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eggsalad
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EEC issues, fuel drip from Active Carbon Can

Post by eggsalad »

After a long ride today, I discovered gasoline dripping on to my exhaust.

That's NEVER a good thing!

Took off some panels and did some poking around. The only possible place the drip could have been coming from is the "Active Carbon Can", which is part of the Evaporative Emissions Control system.

I'm not at all an expert, but from what (little) I do know, the function of the EEC system is to vent the fuel tank vapors (from evaporation, hence the name) back into the intake manifold, rather than to the atmosphere.

Vapors. Not liquid gasoline.

Upon doing more research, it appears that the main cause of liquid gasoline getting into the carbon canister is overfilling the tank. (note: that's not Buddy or even scooter-specific information, just what Google spat out when I asked it why there was fuel in my carbon canister.)

NOW... it's entirely possible I had overfilled my tank, because:
(a) that's easy to do on a scooter - it doesn't click off the pump like a car does
(b) I had gotten gas about 2 miles before the end of my last ride
(c) It was about 20F warmer today than when I bought gas (80F vs. 100F)
(d) It was only the 2nd time I'd bought gas since I purchased my Buddy

SO... my first question is... Is my diagnosis of "overfilled gas tank" correct?

And if so... what is the proper stopping point when filling my Buddy's gas tank to prevent this from happening again in the future?

As always, thanks in advance!
scootERIK
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Re: EEC issues, fuel drip from Active Carbon Can

Post by scootERIK »

eggsalad wrote:And if so... what is the proper stopping point when filling my Buddy's gas tank to prevent this from happening again in the future?
Depends with gas tank you have. There are at least two different tank, really I think there are at least three.

In my opinion the easiest tank to fill is in the one they started using in ~2009. It has an extra ring of metal with some small holes in it which is your fill to line. If you look at the picture below the red arrow is pointing at the ring. With your scooter on the centerstand you fill the tank until the gas gets to the level of the ring with the small holes in.
Image

If you have the metal gas tank that doesn't have the ring in it then you have to stop filling as soon as the gas get to the "neck" of the tank, which is 2-3 inches down, if you want I can try to post a picture tomorrow. This tank is very easy to overfill. Overfilling it can even cause your scooter to not run right for 10-20 miles while the overflow drains.

If you have a plastic gas tank I don't know exactly how much gas you can put in it.
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eggsalad
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Post by eggsalad »

Thanks! As I have an '08, I don't have the "neck ring" but I can certainly shoot for below the neck.
HowHH
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Post by HowHH »

Pop the cover off of the air filter and see if you have any gas in there. I've never had a problem with the carbon canister, but I've had more than one failed petcock with the same symptom. May also be a problem with the carburetor float valve.

When my first petcock failed I went though 2 or 3 replacement petcocks that were bad from new. Float valve was fine.

Here's a few threads to get you going:
http://www.modernbuddy.com/forum/viewtopic.php?t=30452
http://www.modernbuddy.com/forum/viewtopic.php?t=30111
http://www.modernbuddy.com/forum/viewtopic.php?t=30191
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buzzvert
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Post by buzzvert »

There's some anecdotal evidence that the carbon canister, which works suitably to reduce emissions when new, doesn't do a whole lot after it's saturated- over time, or after a few overfills. I'm very environmentally conscious but readily make an exception when removing the canister and emissions system as long as a catalytic remains in place. Doing so voids warranty and not a decision to make lightly.

Also during an overfill, gas can pool around the top of the tank or the fuel level sender, and can drip later. if it's dripping onto the exhaust, definitely inspect your fuel lines, clamps, petcock and run-up to the carburetor. the nipple on the petcock is pretty brittle and can break. Also, I just wanted to say "nipple" and "petcock" in the same sentence.

Thank you, I will be here all week, try the veal.
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buzzvert
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Post by buzzvert »

Also, a full tank can splash around a bit, and get raw fuel into the venting system. I suspect since you had just filled up and had a hot bike, that could well be the case.

If it's not making your garage reek of gas while it's sitting, it's likely fine.
scootERIK
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Post by scootERIK »

eggsalad wrote:Thanks! As I have an '08, I don't have the "neck ring" but I can certainly shoot for below the neck.
I just double checked my '08 gas tank and I was wrong when I said to fill to the neck, you want to be ~1/2 to 1 inch below the neck. Which is about 1.5 inches from the top of the tank.

Another method you can use to fill the tank is to turn the engine off but leave the key in the ON position so you still have electricity running to the fuel gauge. Now as you are filling you can watch the gauge to see when the tank is full. You will have to fill the tank a little slower since some of these gauges don't move that fast.

If you run your tank down to empty you should be able to put ~1 gallon in.
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