Tank not ventilating properly?

Hello All,

My 2016 has become testy in the FL heat. It starts right and up and runs fine when cold. The problem begins following a ride and after a stop (especially in the FL sun/heat). When I go to start the bike following a hot ride, it struggles. I typically have to 1.) open/close the gas cap immediately before starting or 2.) goose the throttle when starting. I've also noticed a "buzzing" sounds when I park in the garage after a ride. The buzz stops when I open the gas cap, then starts back up until the bike cools off. I estimate that something with the tank isn't ventilating correctly.

Today I attempted to remove the gas tank so I could inspect the ventilation hoses. This was not as easy as I thought it would be (at least for me). The rear bolts near the battery were particularly difficult. I noticed another post that mentioned the rubber "well" bushings had some sort of integrated screw and that the top bolts should have come out leaving the rubber bushing in place. Instead, the entire bushing started backing out on both sides. Maybe I should have used needle nose pliers to hold the rubber bushings in place while back out the top bolts?

Can you guys tell me what I'm screwing up in terms of removing the gas tank? Any recommendations on how to diagnose the hot starting/buzzing issue? I also noticed that the fitting on the back of the tank (clutch side) didn't have a hose connected to it at all. I did try compressed air to clear out the drain in the gas cap area. No luck, and it didn't seem to flow through the line at all. My bike has no modifications other than slip on exhaust. The charcoal canister has not been modified. Thanks!

Chris

Yes, you have to hold the rubber for the rear screws. On the cap, you can take it off. Cap drain is on one side, vent on the other. If your charcoal canister is still hooked up, disconnect it. The noise you hear is the inline valve that goes to the canister. You should be able to spray carb cleaner in the vent tube in cap area if you take cap off. Put cleaner down tube then compressed air to clean out tube worked for me.

Thanks for the tip GuzziSteve. I didn't realize that I needed to remove the cap to get to the vent. Makes sense now. I'll remove the gas cap assembly then try the carb cleaner & compressed air clean out method.

While we don't have the charcoal canister and vapour recovery system on bikes in Oz I am familiar with the problem you're experiencing.

The issue is that the tank vents through a pressure release valve, (It's that that is making the farting noise when the bike is parked when hot or in the heat.) this in and of itself is harmless and is in fact how the system is supposed to work BUT........Once the pressure has overcome the valve the vented *gasses* from the tank, which are a mixture of expanded air and vented hydrocarbons from the petrol in the tank, pass into the charcoal canister which absorbs the hydrocarbons while allowing the now *Scrubbed* air component to vent to atmosphere through the exit pipe of the canister.

The problem with the hard starting is caused by the same problem but in reverse. When the engine starts cranking the two hoses connected to the inlet manifolds start 'Sucking' air back through the charcoal canister and this extra air gets loaded up with hydrocarbons from the charcoal stored in the canister. The canister in effect becomes a 'Battery' for hydrocarbons which then discharge when the fresh air passes through the canister,

Unfortunately the ECU has no way of compensating for this, what is effectively, extra fuel. So the mixture becomes far too rich. So rich it doesn't want to combust! Until the engine has cranked enough and drawn enough air through the canister to purge it this rich condition will persist and the engine will be reluctant to start.

My own feeling about the canister is that it is a perfectly fine anti pollution device as long as it doesn't affect the vehicle's running. With larger motors and/or cooler climates they rarely cause a noticeable issue. On smaller engines though they can, especially in places that get hot and particularly in summer! While I've never been to Orlando I have been to Florida in the summer and if I'm right it is hot and humid? That being the case I'd think that this would be one of those times and places where removing, or disconnecting, the evaporative emissions control system would be wise as it is interfering with your enjoyment of the bike and it's running.

The process is very simple. You can either remove the hoses and their fittings from the inlet manifolds and replace them with a pair of 6mm x 10 bolts, (In other markets small, domed, Allen head bolts are used.) with alloy sealing washers on them. Then the canister and all it's hosing can be removed and the vent nipple on the tank can have a hose attached and run down to the clip that holds all the other vent and drain hoses just inboard of the right hand riders footpeg and just be allowed to vent to atmosphere. The bits you valve taken off can be boxed and stored so if you want to you can pass them on to the next owner. If you don't want to remove the manifold fittings just join them with a hose or cap them.

Doing this is not without its downsides. Firstly when you park your bike after a hot ride, if you keep it in a garage it may make the garage smell of fuel as the hydrocarbons that were previously stored in the canister will simply vent to atmosphere. Also if you park the bike up with a really full tank heat soak-back may cause it to expand the fuel to the extent it will be pushed out of the tank through the hose and puddle on the floor! My second GRiSO is particularly bad for this, in fact if I over fill it at petrol stations on even a warm day by the time I've gone in and paid it will be having a little wee which is most vexing. I'm hoping when I swap the tank it may fix it because I can't see any logical reason why the green tank does it but the yellow tank on my other bike doesn't!

Anyway, once you remove the system I'm betting your problem will vanish.

More info.
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Pete,

Thank you for the generous response. All of that makes more sense having read your explanation. I imagine that after about 6 years of ownership, the charcoal canister may be pretty well saturated. This hard starting in the heat is a rather new phenomenon for my particular bike. It started last year and has become more consistent.

One more question regarding the tank's actual ventilation that confuses me: Charcoal canister aside, why would my bike start without protest if I release the pressure from the tank by opening the gas cap? This seems to temporarily relieve the hard starting problem (rinse and repeat each time I make a pit stop in the summer heat). Perhaps it's time to remove the canister while simultaneously addressing the ventilation?

Oh and yes, Orlando is HOT & HUMID in the summer. Not enough to keep me off my Guzzis early in the morning though!

Thanks,
Chris

Chris,
You’ll be happy like me once all that crap is taken off.

Pete, wonderful explanation.

daviscr5 wrote:

One more question regarding the tank's actual ventilation that confuses me: Charcoal canister aside, why would my bike start without protest if I release the pressure from the tank by opening the gas cap? This seems to temporarily relieve the hard starting problem (rinse and repeat each time I make a pit stop in the summer heat). Perhaps it's time to remove the canister while simultaneously addressing the ventilation?

Just a guess but even the slight increase in pressure in the tank due to the impedance of the two way valve in the venting system will increase the fuel pressure in the rail. The higher the pressure, (The pressure relief valve is internal to the tank so it will have no effect on over pressure in this circumstance.) the greater the amount of fuel delivered with every injection pulse so once again an overly rich condition is engendered. By depressurising the tank by opening the lid you remove this pressure anomaly and the pressure and therefore delivery volume returns to what it should be. Taking out the two way valve should, if my theory is correct, rectify this issue. Albeit at the price of a bit more petrol pong in the garage.

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The gas withing the canister is sucked back out as you ride the bike, so in theory, after a ride it's empty again, ready to retain any fumes generated.

That explanation makes sense.  I have my work cut out for the weekend and will report back once I've had an opportunity to address.  Thank you all for the assistance!

[/quote]

Just a guess but even the slight increase in pressure in the tank due to the impedance of the two way valve in the venting system will increase the fuel pressure in the rail. The higher the pressure, (The pressure relief valve is internal to the tank so it will have no effect on over pressure in this circumstance.) the greater the amount of fuel delivered with every injection pulse so once again an overly rich condition is engendered. By depressurising the tank by opening the lid you remove this pressure anomaly and the pressure and therefore delivery volume returns to what it should be. Taking out the two way valve should, if my theory is correct, rectify this issue. Albeit at the price of a bit more petrol pong in the garage.[/quote]

Good morning If you want to see what i did to my GRiSO we can meet up as Im over in Melbourne and Orlando isnt far ,Ive removed my canister system on my 07 and on my previous 15 both had the same issues . But the quickest fix without removing can is just removing the blue and orange valve and putting a hose barb in that will let it free vent and no more fart and pressure when cap opened

Tim Henry wrote:

Good morning If you want to see what i did to my GRiSO we can meet up as Im over in Melbourne and Orlando isnt far ,Ive removed my canister system on my 07 and on my previous 15 both had the same issues . But the quickest fix without removing can is just removing the blue and orange valve and putting a hose barb in that will let it free vent and no more fart and pressure when cap opened

Sounds great.  I feel like I have a plan for this but may very well take you up on the offer.  I'll PM you. Thanks-