Modern Vespa

I'm having a problem that I'm nearly positive is being caused by the goofy evap system malfunctioning. I've already removed the evap hose at the carb but I think I now need to remove the gas tank vent hose. Yeah, it's been overfilled more than once . The scoot in question is a BV200. The charcol canister and the two-way roll-over valve is under the seat like on the BV500. My question is which one of these two items does the gas tank vent hose go to? I think it goes to the roll-over valve on the left side (non-throttle side). Is that correct? If I just cut the larger hose that runs to the roll-over valve and position it to point to the ground I'm thinking that should take care of it. My symptoms are stalling and not restarting for 1/2 hour. This seems to be aggravated by parking it on the sidestand or parking it on a hill with the front end pointing upwards. That's why I think the tank vent runs along the left side. Am I on the right track here? I really don't think it's the fuel filter because it runs perfectly once it starts. The air filter is clean, there is sea-foam in the gas, and the spark plug is relatively new and in good shape. The valves are nearly due for adjustment but it runs well otherwise and starts when cold perfectly.

Bob

Bob, I just got thru working thru to disconnect of the overflow hose to the evap canister on my GT200...see this recent post. Please keep in mind this is a GT200 carburator scoot...the nuances pertaining to your BV200...I do not know...

https://modernvespa.com/forum/topic50298

This method involved removing the rear rack and then re-routing the disconnected overflow hose. Another alternative would be to disconnect from the filler neck and attach a ~ 3 foot, 1/4" fuel hose and route it down to ground to drain / vent. This way if need to reattach...you remove the 3 foot hose and resecure the original overflow hose.

Then there is the..."Hey I don't have the time to fuss with this!"...pics below on another GT200 (one in our local group) who simply had the overflow hose cut at midpoint and left to hang there...works for him...


Hope this helps!

Hi TB- Thanks for the reply. What I'm trying to determine is if the gas tank over-flow hose goes to the rollover valve (round white thing) or the black box charcol canister. It looks like on the BV it goes to the white rollover valve. It's very hard to determine what goes where under the scoot. To me it looks like the hose from the black box goes to the manifold. Clarification is what I need. Help!
I've been stranded after it stalled or wouldn't restart twice in the last three days....

Bob

Vic

I'll send your question to my mechanic to see if I can get some clarification on this. He's a certified Vespa/Piaggio guy.

What is happening is that pressure is building up in the gas tank because the charcoal filter is saturated with fumes and/or gas.
If you take off the plastic section that covers the gas tank filler and loosen the right hand panel above your right foot, you can see where the overflow line connects to the top-right-side of the gas tank. If you follow that line, you can cut it and run it down between the frame and the gas tank towards the ground. I just wedged it between the tank and the frame behind the right-side, drivers foot rest.
If I understand correctly, you've already disconnected your line from the canister/rollover valve that leads to the throttle body and plugged it. Once the overflow line is run towards the ground, the tank can breathe again and by plugging the line into the throttle body, nothing else is connected to anything that can affect your engine or gas tank. It's just sitting there. You can leave the remaining equipment where it is or remove it. I removed mine and the cover over the equipment that is under the seat. I sealed the holes that were left with plugs and rtv silicone from my local auto parts store. This gave me more storage under the seat. Did this over 2000 miles ago and have never had a problem.

I'm trying not to remove that center panel right now. I can't figure out how to remove it without scratching the paint on the panel above it. I'd like to cut it further back where the line enters up into the space under the seat. What I'm trying to determine is does the gas tank vent line go to the charcol canister (black box) on the throttle side or does it go to the 2-way valve (white round thing)- non-throttle side?

Thanks- Bob

By the way the scoot has a carb.

Bob,
Unfortunately, I can't remember what was where because it's been around five months since I removed all the evap equipment from mine. I remember having to remove the side panels to get at everything for removal but the exact sequence, I can't remember.
To remove the center panel that surrounds the gas filler.....take off the gas cap and the rubber flap that sits over the filler neck........then, take off the screws on each side and pull it up from the front enough to reach in and disconnect the cable that springs the gas door open. Then, you can maneuver it from the back and lift it off.

Since you have a carburetor, rather than fuel injection, you're going to need to leave the hose that goes from the whole canister assembly to the carb, open. Some have put small air filters on them and some leave them open.

From looking at the diagram in the shop manual it does look like the tank vent hose goes to the roll-over valve as opposed to the charcol canister. Hopefully Dutch's tech will know for sure. I may try riding tonight with the gas cap off to see if this makes a difference.

As an aside, yesterday it stalled in a not-to-good part of town at dusk. A local dude watched me coast to the side of the road. He came up and asked the usual questions about the scoot and I explained that I was having a little trouble lately with it. He said "I'm gonna hang out with you until it starts- this isn't a place where you want to be broken down". Really cool guy. He and I talked about everything under the sun and 1/2 hour later- it started right up! I'll be heading to more familiar territory tonight!

Bob

Just wanted to bump this to get more eyeballs on it..

I just removed all of the evap parts on my BV200 this weekend. The hoses are:

Tank vent to rollover valve - Larger hose running up the left side and entering "trunk", then going into bottom of rollover valve. I cut this one just outside of the trunk for now.

Carb vent - smaller hose running up left side. Goes to T in trunk. T also connects to rollover valve and charcoal can. I cut this one near the carb. Need a small filter to help keep small critters out of carb.

Charcoal can to intake manifold - large hose running up right side entering trunk and into bottom of charcoal can. I removed this from the manifold and used a 1/4" vacuum plug to cap the nipple at the manifold.

I also took off the side panels and removed the brackets that held the charcoal can and the rollover valve. My helmet now fits in the trunk!

Thanks LotusMike! You've confirmed my suspicions. I got to get out there and disconnect the tank vent hose tonight. I'll figure out a more permanent solution to routing it somewhere once I confirm that this is the problem.

Thanks a million.

Bob

I removed the whole system from my 2006 BV500 the easy way. You might look at my input titled CHARCOAL CANISTER REMOVAL - ONE MORE TIME which I posted on May 13, 2009. I have had absolutely no problems since I did this fix.

The easiest way to think about this system is think - overflow gas hose to rollover valve - rollover valve hose to charcoal canister - charcoal canister hose to manifold. The overflow hose comes UP through the hole in storage area under the seat on the left side facing forward. The charcoal canister hose goes DOWN through the hole in the storage area under the seat on the right side facing forward.

Hope this helps. I think they all function the same be it a fuel injected system or a carb system. These systems work well on automobiles but not so hot on scooters of any size.

They do? Quite. Bloody useless by all accounts. Stupid, stupid, lawmakers who have no engineering suss whatsoever.