Evap removal from V7III

[Godfrey]

Todd's been stressing I should can the evap system and its 'vacuum leak' since I started talking to him about the ECU reflash for Racer. Well, this morning, my second test of the ECU map with a stone-cold start on a chilly morning proved conclusively that Todd's work on that is absolutely spot on: Start, fifteen seconds to get a little heat into the cylinders, ride away ... no stumbles, no lean spot, nada. Just perfect. Thanks Todd!

But, as I returned home a couple of hours later, I noticed that the idle revs were acting a little "funny" and that the throttle seemed a hair "sticky." No idea why, but killing the motor and restarting cured both symptoms. Two miles later as I pulled into my driveway, the sticky throttle sensation was back again.

On a hunch, I opened the tank and heard a gasp of air, there was a vacuum building up in the tank. Ah hah! the evap can and it's valve were screwing up as I was told.

I spent a bit of time with the V7III ABS Service Station Manual PDF and finally found the evap system on page 234-237 as "Sistema evaporativo canister". Now I could see where they were located approximately and understand the operation completely. Vacuum line connects to the evap can to draw fumes through the tank breather after passing them through the charcoal. The valve is supposed to limit how much vacuum is applied and vent when it's too much. Obviously, it wasn't working right. A cheap and crappy valve, essentially, is the cause of the problem. But the system is ugly anyway and almost totally unnecessary for the evaporative emissions of a motorcycle.

Not having much time, I pulled the seat, side cover, and starter cover. Yup, there are the lines from the intake manifold to the canister under the gearbox, there's the tank line with the valve in it. Looking at the flow from manifold to canister, it was obvious how to do the quick'n'dirty: I cut the line going to the manifold and stuffed a blanking plug into it to stop the vacuum leak. I then cut the line coming from the tank vent and going into the canister just above the valve gizmo, and cut the bottom line and the valve off the canister. No more vacuum leak, and the tank now vents to atmosphere exactly the same way my LeMan V tank did ... just a small line leading from the top of the tank down behind the starter.

Procedure:

- remove seat
- remove left side panel (three bolts)
- remove starter cover (two bolts)
- locate vacuum tap line from manifold to canister under the gearbox
- locate breather line with valve connected to canister
- cut vacuum line and block it (I glued an aluminum slug in place)
- cut breather line above the valve and below at the canister inlet
- leave the breather line open ended behind the started ... put a filter on it if you worry about environmental dust getting into the tank
- replace starter cover
- replace side cover
- replace seat​

You're done.

note: Another one of those cheap clip nuts broke when I removed the side cover. Glad I got six better quality spares! That's three now... I'm going to pick up another dozen because I see them all over the place on this bike.

I'll clean up my work next time I get a chance by removing the vacuum line and canister completely and using a good vacuum tap plug, maybe extend the breather line down an inch or two and put a little filter trap on it. But this will suffice for the present.

I'll see what its behavior is on my run out for dinner tonight.

BTW: Is this little valve on the breather line what's referred to as the "tip valve"? Or is that something else still? ... Thanks!

G

 

[Godfrey]

Checking my work: Last evening's run for dinner ran about 50 miles or so, up the freeway through dense traffic, a bit of pootling around in town, then back home via a different route up and over the hills on surface streets and a fast blast down the other freeway.

In all of it, Racer ran flawlessly. Perfect throttle response, excellent power, no "funny" idle, no vacuum in the tank. The low fuel light flicked on about 6 miles from home so I stopped and refilled the tank at the gas station a half mile away on the way in. The second full tank-load ran the same 49.9 mpg and just shy of 200 miles from full to warning. Perfect.

Today I'll hunt up the appropriately sized vacuum connection cap so I can remove the evap charcoal canister and its vacuum line in their entirety. One less bit of useless junk to clutter up Racer...

G

 

[Godfrey]

I took some pictures while working on disabling the evap can yesterday. Hopefully this will help someone out there... :

Illustrated Procedure:

- remove seat
- remove left side panel (three bolts)
- remove starter cover (two bolts)
- locate vacuum tap line from manifold to canister under the gearbox
​

- cut vacuum line and block it (I glued an aluminum slug in place)

Follow the line and cut it in a convenient place, then block it ... particularly the upstream side that comes from the inlet manifold.​

- locate breather line with valve connected to canister
- cut breather line above the valve and below at the canister inlet​

- leave the breather line open ended behind the starter ... put a filter on it if you worry about environmental dust getting into the tank (but it ain't going to happen...

- replace starter cover
- replace side cover
- replace seat
​

Hope that's clear ... ask if you have any questions.

 

[GTM®]

Thanks for posting Godfrey.

A few notes to add...

• Above applies to all '13-15 V7s, however the '16 V7 II has the evap can in between the intake manifold, aft of the engine. All else is still valid.
• If you plan on leaving the evap can in place... Instead of cutting the (tank breather) tip over valve line and removing it, I highly recommend gutting the valve by popping it apart (using a hair dyer to soften the plastic), or installing a fitting that allows the vapors to flow into the canister if you don't want any fuel smells in your garage. If you leave vented to open air, be aware that fuel will flow from this line while the tank is topped off at any sudden stop or side-standing of the bike.

 

[Godfrey]

Hmm.

I didn't notice any fuel spilling or fuel smell after I topped off the tank last evening. The bike was on the side stand at the gas station and again in my garage before I put it into its parking spot. The driveway down into my garage is pretty steep so I have to use the brakes there pretty hard too...

I'll keep an eye on it, I imagine it could happen in certain conditions. I've had it happen on other bikes that were not designed with an evap system like this too, particularly if I over-filled the tank. I like that the Guzzi has a nice little cage in the tank filler that gives you an indication of when you're at the full point.

I'll probably get your filter anyway ... it's a good idea no matter to filter all vents and such.

 

[Godfrey]

Addendum:

Chatting with a mechanic at the dealership yesterday about how my evap canister has 'fallen off' ... ... he said to be sure that when I remove the no longer needed vacuum line:

"... Don't just slip one of those rubber vacuum caps on and leave it at that. Any backfire from the engine and it could just pop off, leaving you stranded unless you can figure another way to seal the hole. It's best if you can unthread the vacuum tap and block it with a bolt and some sealant. A vacuum cap fitted with some sealant and a tight metal retaining clip is another solution that works. Actually, what you've got in place now works pretty well too because a backfire has some flexible hose to fill before exerting pressure on the blocking slug, that makes it less likely to blow off. ..."
​

Fun fun fun.

 

[TimmyTheHog]

Maybe I am missing something...but what is the purpose of removing the starter cover?...

then again, I have a stone, so I don't know if there are any differences in terms of covers...o.O

 

[roadscum]

Maybe I am missing something...but what is the purpose of removing the starter cover?...

then again, I have a stone, so I don't know if there are any differences in terms of covers...o.O

And..... what's the advantage of disabling the evap system???

Paul

 

[Godfrey]

Removing the starter cover allows much better access to the hoses and other bits of the evap system. It's only two bolts ... much easier to remove and replace it when you're done than to work around its obstruction.

The primary advantage of disabling the evap system is to eliminate the three problems it causes: the intake leak that happens when the regulator valve malfunctions (which destabilizes the idle and throws the intake mixtures off), and the destruction of the fuel tank and pump that can happen when the regulator valve malfunctions and applies full engine vacuum to the gas tank.

If you really don't want to disable the evap system, and I can understand that desire, the thing to do is to figure out a significantly more reliable and effective regulator valve setup to eliminate these problems. The amount of vacuum being applied to the evap can has an influence on the air-fuel mixture, the idle speed, and the amount of vacuum being applied to the tank, so once you find a reliable valve that doesn't constantly fail and applies the correct amount of vacuum to allow the intake to scavenge the fumes properly, you than have to put the bike on a dynamometer and develop the best fueling map for the ECU so that the engine runs properly.

I actually would have preferred to leave the evap system in place, but when the idle started going wonky and I felt the amount of vacuum that the tank had in it, I changed my mind and decided it posed a serious danger to the health of the engine and tank.

 

[roadscum]

In my 55+ years of riding and ownership of more then 55 differeent motorcycles I've never encountered a problem caused by the evap system nor have I ever heeed of anyone else encountering a problem. Maybe I'm just a lucky guy.

Paul

 

[Godfrey]

Well, Paul, I've also been riding a long time (since 1975) and had a lot of motorcycles over the years (about 80 in total). This 2017 V7III Racer, however, is the very first motorcycle of all of those that actually has an evaporative emissions system.

... And the evap system's vacuum regulator valve failed nearly immediately. The gentleman at Piaggio/Moto Guzzi in Italy who had to program the engine's control computer (ECU) around its foibles told me, personally, that it was a POS and should be removed if possible.

From what I read here and on other motorcycle forums, this is not an isolated instance of problems caused by this system.

There's a first time for everything.

 

[roadscum]

Well, Paul, I've also been riding a long time (since 1975) and had a lot of motorcycles over the years (about 80 in total). This 2017 V7III Racer, however, is the very first motorcycle of all of those that actually has an evaporative emissions system.

... And the evap system's vacuum regulator valve failed nearly immediately. The gentleman at Piaggio/Moto Guzzi in Italy who had to program the engine's control computer (ECU) around its foibles told me, personally, that it was a POS and should be removed if possible.

From what I read here and on other motorcycle forums, this is not an isolated instance of problems caused by this system.

There's a first time for everything.

Ya gotta do what ya gotta do. Many on my bikes past and present have had evap systems, and my cars to. Never had an issue, never read of an issues on the many forums and blogs I visit regularly. My nemisus was a failed fuel filter within one week and 1200 miles of taking delivery on a V7 III. Sorry to hear you were bitten. What was the cause of the evap failure you experienced?

Paul

 

[Godfrey]

Oh I hear ya. I’d have left it in place if I didn’t think it put my engine and fuel tank at risk. Evap systems in cars are a proven good thing, never seen any point to removing one.

But when I can feel the tension on the tank’s sides and that great suck of air when I open the cap, I know somethings not right.

I heard about the fuel filter stuff... PITA. But like with all machines: they break, we fix, we move on. Sorry you had to deal with it.

 

[JACoH]

Lived with a gal in Sacramento in the 1980's, came out to the garage one day and her Yamaha Virago gas tank was sucked in to the frame. That was when they were learning about emission controls.

 

[Godfrey]

You’re inspiring me to think of my own horror stories...

I had an Alfa Romeo Spider that came up with a clogged EVAP system on the way home from Reno, NV about a decade and a half back. The result of being at high altitude when the EVAP clogged meant maximum vacuum in the fuel tank ... when I got back to sea level and rolled into the garage, it sputtered and died. I did some checking ... no fuel flowing. I called my mechanic, he took the cover off the gas tank. It was crumpled like a used foil candy wrapper.

“Well, whatever fuel pump you once had ... I can’t figure out how I’d even get it out of that mess. ...1” We had to cut the tank off its mounting points to get it out of there. Couldn’t salvage a single piece of it.

This sort of problem is a rarity, for sure. Luckily, since that car was an amalgam of three Spiders I had taken apart to build one really nice one, I had a couple of spare fuel tanks and all the various bits of plumbing that had been destroyed. Luckily including a spare Bosch EFI fuel pump and regulator assembly... that would have been pricey to replace!

 

[roadscum]

Lived with a gal in Sacramento in the 1980's, came out to the garage one day and her Yamaha Virago gas tank was sucked in to the frame. That was when they were learning about emission controls.

"Well that sucks.......

Paul

 

[Trout]

When charcoal canisters on cars were first out many were mounted up front, passenger side fender well under/around headlight.
The "old timers" who "topped off" the tank could flood the canister with raw fuel.
Hard starting, black smoke, backfiring were all symptoms.

 

[JACoH]

OK, here is a question...whilst performing the above steps to the hoses, why not just cap the breather inlet on the intake manifold, rather than peg the hose farther down the line?

 

[Godfrey]

Two reasons:

Convenience... I didn’t have in stock a suitable vacuum cap and retaining clamp that would secure it in the event of a backfire.

Access... to get to the vacuum tap and do a clean job requires lifting or removing the tank so I can get my hands in there.

Cutting and plugging the line with a glued-in billet slug was an effective, ten minute job. The line to the slug is long enough to expand and absorb backfire energy too so until I have the moment to remove the line and screw in a solid plug, it will do.

 

[JACoH]

OK, thanks, I did the same but sliced my finger trying to get the hoses onto the slug.