Canisterectomy & Vacuum Line FAQ
can't be out of GAS.!")
compiled & edited by Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.
by Flash #412, Bob #550, Hombre sin Nombre et al
There is a bit of repetition here, for clarity, and because there are more questions than answers. So don't think you're missing something out.
Several F650 riders report an engine that dies and that the solution involves poor electrical connections. If your carburetted bike surges and stalls sometimes, particularly in the rain and it is NOT electrical, it could be your Canister or your Carburettor Vacuum lines.
First check all electrical connections in the ignition system. The connection in the line to the side stand cut-off switch is one place to check.
Another is the fuse box under the seat. There are three fused lines in a rubber mounting. One BMW mechanic has specifically cited the middle fuse line as the culprit. Wherever there is a slide male/female slide connector there is a possibility that there is a poor or intermittent contact which can mean that electrical current is not present when it needs to be.
Others have indicated that the vacuum (charcoal) canister is to blame. Check the lines for kinks and bends and that all connections are tight to the gas tank and carburettor. One owner even suggested checking the drain tubes, that something may be clogging the tube at the opening and not allowing the vacuum canister to not get sufficient air in or out. But then again others have cited that the canister has "mysteriously" fallen off while driving, which has fixed their problem. Please note, the EPA in the United States likes the canisters and if you live in California, make sure it is securely attached so it won't "mysteriously" fall off.
A BMW service bulletin has said most 1999 F650's came with the vacuum hoses on the carburettors installed backwards. The forward port on the right side of the right carb should have a vacuum hose going into the bottom front right side of the airbox (air filter housing). The rear carb port vacuum hose should be connected to the vacuum (charcoal) canister at the top rear fitting. When the hoses are incorrectly reversed there can be excessive suction into the canister. This can cause problems in wet weather when the vent hose near the RIGHT footpeg sucks up water into the canister and the carbs. Check with your dealer for more information.
So which way around SHOULD the vacuum lines go.?
The US Spec. F650 has two vacuum lines connected to the right side of the right carburettor (looking down from a seated position). You might have to remove a plastic panel to get to these, but you can see them without removing anything.
The front vacuum line should go into the airbox. It operates the vacuum actuated valve for the air injector for the Catalytic Converter inside the exhaust system. (More on that below in the last section.) The rear vacuum line should go to the charcoal canister (if you have one), or it may just be plugged with a screw or something if the canister has been removed. If you have these ports and the vacuum lines have been removed or disconnected, they must be plugged or capped to close them off for proper operation.
The European-spec. bikes do not have an EPA canister.
So why Does the Bike feel like it is out of Gas ?
There are two "vent" hoses attached to the gas tank. One is a vent and the other is an overflow drain, connecting to a small drain hole in the left side of the tank cap filler well (under the gas cap). It's the hose running on the left side of the gas tank under the tank cover which ends as one of the drain tubes by the left hand footpeg . When you overfill your tank, it drains straight out the overflow onto the ground. Note that when you close the gas cap, the space this hose reaches is SEALED OFF from the interior of the tank. The OTHER hose on the right side of the gas tank under the tank cover is the vent hose. This vent hose connects to the interior of the gas tank thru a series of check valves contained inside the filler cap. The other end of this vent hose runs to the charcoal canister at its center rear fitting. The front (lower) fitting on the canister goes to a drain hose which ends by the right footpeg.
This can cause problems in wet weather when the canister drain hose near the RIGHT footpeg sucks up water into the carbs.
The vent hose goes to a (stupid) charcoal canister. There are two other hoses connected to this canister. When the tank develops overpressure, the liquid/fumes go into the canister and are collected by the charcoal. There is a big hose that leaves the canister and goes to the air, by your right footpeg. This is for fresh air INPUT to the canister. The little tiny hose goes to the carb. The carb draws a vacuum, which sucks on the little hose, which sucks all the nasty hydrocarbons out of the canister, to be replaced by fresh air, in a limited quantity. If it got too much fresh air, the bike would run too lean. When the carb vacuum hoses are reversed there is too much vacuum from the carb into the canister. Instead of very gently sucking gas fumes that have collected in the charcoal canister, too much air is sucked thru the canister and up the drain. This can cause problems in wet weather when the canister drain hose near the right footpeg sucks up water into the carbs. Then canister can fill with water or dirt and clog, or eventually suck water into the carb, or clog one of the smaller vacuum tubes. So instead of getting too much fresh air... it sucks on the tank, creating a vacuum, which makes the bike act like it is out of gas.
What to do if your Canister "mysteriously" falls off:
You take the little hose from the carb and plug it up. The best place is to cap or plug the (rear) port on the carb. One handy place is the junction on top of the airbox, just behind the tank, under the seat. You take the long hose from the tank to the canister and reroute it to the place where the hose that used to go from the canister to the footpeg went.
In this configuration, the carb doesn't suck on the inside of your tank. And the tank can "breathe" fresh air if it wants to.
I have a canister, in a box in my garage.
NOTE: In the event that the canister has "fallen off", the rear carb port must be capped or it will affect proper idle and starting, not to mention sucking dirt and water directly into the carb. The vent hose to the gas tank, which was previously attached to the Canister, is now used as a drain vent, and is routed to the hose bundle by either footpeg. (I used the same side as the carb, the right footpeg hose bundle.)
There is a brass orifice in the rear carb vacuum line going to the canister. It is actually a pinhole restrictive orifice which can clog. It should be replaced or the tank may experience vacuum problems. Some people replace it with the smallest size plastic fuel filters, some people use a similar plastic nylon connector (which is not restricted) that is leftover from the removal of the other canister hoses.
Removing the CANISTER will not affect the catalytic converter. Removing or plugging the AIR INJECTOR will kill the cat. The canister is NOT the same thing as the air injection system. The canister is an over-glorified, poorly engineered gas tank vent. The air injector is used to inject fresh air into the exhaust stream, with good success for over twenty years.
Some Euro bikes ('95-'96) may have the catalytic converter, but not the vacuum actuated valve and the air injector system for the cat. These bikes MAY not have ANY vacuum ports on the right carb, nor any connecting hoses there.
Canister Removal Notes:
Note:.! Even with the vacuum lines correctly installed, a missing orifice would probably cause excess vacuum in the fuel tank - the orifice is meant to limit the vacuum in the system. Installation without it would likely cause excess vacuum in the fuel tank, and subsequent fuel flow problems/vapor lock.
regards to the Brass Orifice, there is no contradiction in the above
description, as we are looking at 2 different cases. The FAQ deals with two
items, (A) Canister Removal & (B) Vacuum Line Re-Routing, as the Title
Suggests. The "Outta Gas Symptoms" could be (A) or (B) as per the first line
in the symptoms section.
Case 1: If you DO REMOVE your Canister, you should take out the Brass Restriction and "Some people replace it with the smallest size plastic fuel filters, some people use a similar plastic nylon connector (which is not restricted) that is leftover from the removal of the other canister hoses. "
Case 2: If you DIDN'T REMOVE the Canister but are Routing the Vacuum Lines, you should NOT remove the orifice as .... "Note:.! Even with the vacuum lines correctly installed, a missing orifice would probably cause excess vacuum in the fuel tank - the orifice is meant to limit the vacuum in the system. Installation without it would likely cause excess vacuum in the fuel tank, and subsequent fuel flow problems/vapor lock."
If you're considering venting under the seat, the only problem with venting high under the seat instead of the footpeg, if you ever lay the bike down or slightly upside down, or if you overfill the tank, there's a possibility that raw gas will discharge from the end of that hose. There's a good reason why the emissions canister drain was originally located at the footpeg.
My canister created a vacuum in my tank from the first day that I owned my bike. My dealer then retrofitted my tank vacuum line with a new and improved restrictor, which did nothing to improve the venting of my tank. When I removed my canister, I plugged the line to the carb and removed the restrictor that I found on the vent line near the rear of the tank. Now the only restrictor that I have on my tank vent line is a small gas filter that I installed where the restrictor was located, which is attached to a hose that I routed to the rear of the bike and stuck through a hole in the black plastic cover, near the former location of the canister. My tank has been venting just fine for almost 5 years, now. Richard #230.
worked perfectly for me (and should be all you need to do):
1- Remove canister from the bracket.
2- Unhook all three hoses from the canister. One drains by the right foot peg, one goes to the carb, and one goes to the gas tank.
3- Discard the canister and hose that drains by the footpeg. Bye bye.
4- Plug the hose going to the carb. I plugged mine with one of the bracket bolts from the canister.
5- Reroute the hose from the gas tank to where the old drain hose was (by right foot peg). Cut it to an acceptable length.
6- Done. Grady (Aus TX) - 13-Aug-02
found a metal restrictor in the vacuum line running from the rear connection
on the carb to the cannister. I simply removed it (and the rest of the line
running back to the cannister) and screwed a suitable sized bolt into the
remaining vacuum line to plug it.
The other (vent) tube running from the tank to the cannister I just tucked up under the seat behind the latch mechanism. Instead of a filter, I covered the end of this tube with a small swatch of cotton cut from an old t-shirt and held in place by the stock spring clamp. Works just fine, and keeps out the bugs.
When I was performing the Canisterectomy, I noticed that the vent line from the tank had an accumulation of oily gunk in it. There was enough so that when I blew through it, it gurgled and dribbled out the other end. I wonder if this caused some of the problems we've heard about? I plan to periodically check this tube to make sure it's clear and free-breathing. Bob#550 (Olympia WA).
We have no cannisters in Canada and the two tubes come together at a "T" junction on the left hand side of the tank bracket just under the seat (or at least they do on my bike). So all you have to do is make one disconnection at the T. Just to be sure you don't have a cannister look for a big ugly black thing at the back of the bike near your coolant reservoir. It looks about the size and shape of a small can of baked beans. Sean #1015 Ottawa Canada.
Wet weather problems. Since they're '99 models, checking the vacuum lines from the carbs would be my first recommendation. Mine (also a '99) were reversed from the factory. Simply connecting the high vacuum one (nearer the engine) to the airbox and the low vacuum one (furthest from the engine) to the cannister made it run much better. I left my cannister on for the first 16000 miles with no problems, even in the rain. At the 18000 service (in my own garage) it finally "fell" off! Bob#550 (Olympia WA)
Has anyone fitted a Container where the Canister WAS?
Ron #304 from Texas has this set up on his bike. The PVC pipe mounts where the canister was. He used a cap on one end of the PVC pipe and a screw on cap on the other. It was big enough to fit his tool kit. Seth #972 Springfield, MO.