95 R100RT - shed fuel supply

[73043]

I have a problem that comes and goes, bike will run for a while, then run on 1 cylinder is seems like, and than stop.
During the winter a got the bike dual-plugged, and also fitted a SilentHektik ignition system.
I adjusted the ignition and testdrove a week ago, bike seemed to run better than ever. Next morning drove off for work, bike stopped after 5 min drive. I suspected the rotor bolt, where the ignition signal is picked up, to have gotton loose. It sure didn??t take much force to unscrew it. So new adjustment, and bolt fastened with correct force, 25nm.
Today I was gonna test again, it ran 200 meters. Hmm. I hr later I??m gonna chech the ignition with a lamp. It??s right on the mark. So I dress up, planning to go for 2-3 hrs. After 7-8 min., the problems are back. Loosing power, seems like I run one 1 cyl. Turns around trying to make it home. Stops on the side of the road. Right float chamber is dry, seems to be lower than usual in the left one too. With ignition on, not a drop of fuel flowing into the chamber.
I friend picks me up. I??m starting to suspect the fuel shed system;
http://www.realoem.com/bmw/showparts.do?model=0469&mospid=51666&btnr=16_0241&hg=16&fg=13
Back home, ignition on, fuel flows again.
On a bike without this system, european, and older american, does the fuel line run directly from the petcock to the carburator? Or are the sides connected?
I understand it??s not uncommon to remove the system. Anybody else experienced problems with the ?¿shed?¿ system?
There are 2 valves in the ?¿shed?¿. Are the output lines connected? If so, if 1 valve failed, I should have gotton half of normal fuel flow?
Hans
Norway

 

[88bmwjeff]

Snowbum has a good description of the system and how to remove it. But, basically, one valve deals with fuel and the other vapors, so if the fuel one is failing, then it could be a problem. Follow the link to Snowbum's site.

http://bmwmotorcycletech.info/pulseair.htm

 

[73043]

Thanks. I looked it over before I posted. I seems that fuel flow between tank and carburator is suspect. Haynes describes some troubleshooting I??ll follow up on. I might be interested in getting red of the shed system too, need some more inputs.
Hans

 

[88bmwjeff]

A PO removed the shed system from my bike. The fuel line is routed downward from the petcocks with a T and crossover tube that runs underneath the airbox, then finally down to the carbs.

My only complaint with the shed system removed, is that the vent, underneath the tank, is just vented to the atmosphere and on really hot days, I can smell gas. I haven't found a good solution to this. Some people have indicated on hot days, the Shed system dumps too much fuel vapor into the intake system making it hard to start. So, I'm a little skeptical on reinstalling the Shed system or routing a vent tube into the airbox. But, beyond doing either of those, I'm not sure there's much that one can do.

 

[dbrick]

Those symptoms could occur if the fuel tank isn't venting. Do you hear "whoosh" when you open the fuel cap?

 

[73043]

Probably is a vent problem. 1st ride I had 2-3 liters in the tank, and drove appr. 15 km (9 miles). Nothing wrong, bike passed. So filled it up. Next 2 stops occurerd after appr. 5 km (3 miles). I??ve been target fixated on my new ignition, but that have probably worked fine the whole time.

 

[73043]

The vent hose was a bit tricky mounting this time, ended up in a 90 degree bend. If it doesn??t allow air flow, will it starve the bike? If not, and both air vent solenoid and fuel shut off solenoid works, no lines are blocked, I??m left with the fuel cap. Is that likely?
Hans

 

[razz2234]

Mine was having the same problem...fixed it by drilling a 1/8th in hole in the fuel cap...therefore venting the tank from a loc up....

 

[73043]

I was draining the tank, soon gas flow slowed down. Got rid of the bend in the vent hose, flow restored. I think problem is solved. That drain hose need to work properly, lesson learned for me. Thanks for all replies.
Hans

 

[toooldtocare]

Glad your problem is solved. But, if it does come back look at the carbs themselves. I bought a very low mileage 95RT in 98 from a person that could never make the problem you describe go away. He had done a bunch of things trying to fix it.

One day I tackled the job differently. When it stopped running on one cylinder I stopped the bike and dropped the carb float bowls. The left side was empty. I removed the gas line and had plenty of gas flow.

I then sucked on the fuel line to the carb and something came out and almost chocked me. It was a bit of factory sealant used to hold the fuel tube in the carb. At times it would float around and act like a check valve, shutting off the gas to the carb.

The first owner of the bike never found it and spent a bunch of time and money trying to fix it. I found it, but nearly choked to death doing it.

Wayne