r1100gs fueling / running issues

Looking for a bit of advice here. I just picked up a 1998 r1100gs with 69k miles. The bike had been sitting for a while and while it ran, it ran a bit rough. The folks a bought it from werent bmw specialists and thought it just had a bad tank of gas from sitting as long as it had. After putting about 500 miles on it there is a running issue I can tell needs to be addressed.

It runs ok at low speed (a little surging here and there) and all RPMs but at about 60-70 MPH and 4k RPM the bike goes completely flat and won accelerate any further, opening the throttle wide open you can hear the additional air into the intakes, but there is almost no acceleration. If you increase the throttle slightly and gently you can slowly manage to get the bike up to 80 or so.

I tried reseting the motronic, and pulling the CCP just to see if either of those would help, but neither made significant difference. Any thoughts on what it might be?

Sounds like it's not getting enough fuel under load. Could be gummed up injectors or (less likely) a duff fuel pressure regulator. I'd do the simple stuff first - try running a good quality fuel injector cleaner through it.

MattW said:

Sounds like it's not getting enough fuel under load. Could be gummed up injectors or (less likely) a duff fuel pressure regulator. I'd do the simple stuff first - try running a good quality fuel injector cleaner through it.

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Fuel pressure regulator runs at a set pressure. It doesn't increase pressure at higher speeds/revs. So if there's pressure and it runs off idle it's working ok.

Steptoe said:

Fuel pressure regulator runs at a set pressure. It doesn't increase pressure at higher speeds/revs. So if there's pressure and it runs off idle it's working ok.

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I was thinking possibly bunged up internally so couldn't flow enough for high revs / load?

Guess it could also be a blocked filter or dodgy fuel pump...

I Would

make a start by changing the fuel filter ,checking all the lines in the tank, the pick up gauze on the pump as well as the tank drain.
If you have the tank off might as well clean any debris out.

Good luck if no joy Steptoe is your man

Thanks for the feedback. I'll try pulling and cleaning the injectors. I dont have a garage to work in so I may not be able to pull the tank to check the filter. If it comes to that I'll have to find a mechanic =)

fxrjon said:

Thanks for the feedback. I'll try pulling and cleaning the injectors. I dont have a garage to work in so I may not be able to pull the tank to check the filter. If it comes to that I'll have to find a mechanic =)

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You're in London, see 'Old Codger's' post above yours...

Just a quick update for posterity.

I pulled the plugs and used a 9v battery to open them. Blew them out through the front of the injector with carb cleaner. One of them actually had a sizable chunky bit of particle matter in there that fell out. 30 minutes of work and I have a whole new bike.

Bike runs like a champ now! Took it out on a 250 mile ride, runs great, accelerates well. Pretty excited it was easy to correct. I wonder how many people passed on that bike due to that issue.

fxrjon said:

Just a quick update for posterity.

I pulled the plugs and used a 9v battery to open them. Blew them out through the front of the injector with carb cleaner. One of them actually had a sizable chunky bit of particle matter in there that fell out. 30 minutes of work and I have a whole new bike.

Bike runs like a champ now! Took it out on a 250 mile ride, runs great, accelerates well. Pretty excited it was easy to correct. I wonder how many people passed on that bike due to that issue.

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Excellent!