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Discussion Starter · #1 ·
the charcol canister thing is in the way now as i have mounted my water injection pump where it used to sit

i know its part of the emmision control system but not currently needed in this part of the world so can i just bypass it by connecting the two hoses that lead to it together?

thanks
andrew
 
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Discussion Starter · #2 ·
Don't see why not as it only stores the fuel fumes from the tank when the engine is not running, and when you start the engine the fumes are sucked into the engine. Just make sure it is an airtight connection where you bypass it.
 
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Discussion Starter · #3 ·
I have had a look into how the system works and I don't think it's that simple!
The charcoal canister is there for evaporative emissions control from the fuel tank (EVAP). Basically rather than having the fuel tank vent hydrocarbon vapour directly to air like in the good old days (sigh!) the vapour goes through the charcoal canister with an air vent drawing it through on the other side. The activated charcoal stores any HC vapour on the surface of the charcoal granules. When the engine is running a pipe connected to the intake manifold draws air from the air vent back through the charcoal canister and 'blows off' the stored HC vapour to be sucked into intake to be burnt in the engine. A purge valve meters the flow.

I am not sure of the exact effect of ditching the canister and connecting the 2 hoses together although I suspect you may have trouble opening the filler cap and possibly fuel supply/mixture problems especially on start up/idle on a hot day.
If you really must ditch the whole system then I would reroute the vent from the tank to atmosphere somewhere safely (e.g. like on older cars the vent went to the body work next to the filler cap, you could also possibly block it off and fit a vented fuel cap). You will also need to blank off the pipe going back into the intake manifold.

To my mind you may as well find somewhere to stick the canister and keep the system, it will be less hassle.
 
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Discussion Starter · #4 ·
ok, thanks for the replies clive and amp; hh

hmm, at the moment, its just resting on the various wires and plumbing, could just tape it there i guess in the meantime

incidently if you do mount an aquamist then you can unbolt the bracket that this fits in to, turn it over and then there are two convenient slots to mount the pump and then you just bolt it up again, nice

andrew
 
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Discussion Starter · #5 ·
Colin, Andrew,

The Charcoal canister just 'holds' the fuel vapours which are sucked into the intake through an NRV on start up. Its as simple as that. There will be no difference in the pressure in the fuel tank if the canister is removed. The fuel vapour will just sit in the pipe instead. Colin I see what you are saying about fuel vapours entering the inlet on a hot day, caused by higher pressure in the tank. The canister is easy to remove so I would try it removed and if you have problems with idle or start-up, reconnect it or re-route the vent to atmos.
 
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Discussion Starter · #6 ·
ok its gone

see what happens, see if i can advance the ignition with the water injection now, back to 0 degrees (above static) at 5000 with 1.7 bars boost currently...
andrew
 
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Discussion Starter · #7 ·
Clive,
I must admit on first glance I thought it was that simple but I am not sure. I think you may not have realised the signifigance of the actual vent to atmosphere on the bottom of the canister. Forgive the following if you made your previous comments knowing this already.
The Bosche Automotive Handbook has a good diagram of it which I have shown below but ignore the Canister Purge Valve (4), that is replaced with a NRV on the Evo as you say.



What I was trying to get across was the following (with a diagram it is so much easier!):
With the engine off the vapours vent to the atmosphere via the canister, i.e. they come in at (1) HC gets stopped by (2) and the rest gets out to atmosphere (3). In other words the fuel tank vapour pressure will be at atmospheric pressure.
On starting the engine air gets sucked in at (3) picks up the vapour from the canister (2) and goes into the intake via the NRV (4) and pipe (5).

As we know Andrew is proposing to ditch the canister (2) and connect the vapour intake pipe (1) direct to the NRV (4).
The possible problems as I see are this:
a) On a hot day the pipe will indeed fill up with vapour from the tank and it maybe possible that if the pressure is great enough that it will go through the NRV and vapour will sit in the intake manifold. Starting the car with vapour sitting in the intake manifold and possibly further back up the intake system is probably not a good idea. The original unmodified system keeps the vapour in the canister on start up and not in the intake pipework.
b) With the car running at idle the intake manifold will obviously be at a vacuum, this will suck undiluted vapour directly from the fuel tank which may cause further problems. The original unmodified system does not suck directly on the fuel tank pipe but is designed to suck air from the atmosphere along with the vapour from the canister.

I do not know how signifigant the above is but obviously I would have thought if the manufacturers could get away with venting directly into the intake via a canister with no vent to atmosphere then they probably would have done it that way.

I do agree that you can probably try it and see that happens but I would still be wary on hot days.

Andrew,
I have just thought of a quick fix solution. Ditch the canister, blank both pipes securely and fit a good vented fuel cap!

Cheers,

Colin
 
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Discussion Starter · #8 ·
colin

you have raised 2 issues:

1 fuel (or vapour) pushing all the way to the inlet manifold, causing an explosion when the engine is started
2 fuel getting sucked in, in a vacum condition (especially when tank is full), causing at best idle problems

i am truely sick of that silly canister

vented fuel cap (or drill a hole) sounds like the way forward
once this is done i will blank off both lines and remove it

thank you
andrew
 
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Discussion Starter · #10 ·
yeah sure, will be next weekend as i just have the water jet left to install, i have fully mappable ignition so will report on if i can advance the timing and if so where and by how much or...whether it is an expensive flop (nervous now!)

andrew
 
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