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Thread: 1999 R1100RT runs bad, need advice.

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  1. #1
    Registered User bcusack's Avatar
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    1999 R1100RT runs bad, need advice.

    1999 R1100RT 62K miles. Running beautifully until a fill up and after about a mile or two had some problems, would not idle and had no power to pull hills unless I kept the revs up. Under no load on flat roads seemed to run ok. Got to my destination and it would not start once cooled. Got the bike home and removed all the old gas and put fresh gas in, no difference, I?m now pretty sure the fill up was a coincidence. The fuel pump fires up and pressurizes when the systems is closed and freely pumps fuel through the system and out into a container the few seconds it runs when the key is turned. The plugs are new but the spark looks weak , I replaced the plug wires, the coil measures fine yet I had it stressed tested locally and it works well, pulled the BBS and had a little carbon buildup but not bad. The bike will start by holding the throttle open a bit but runs like crap. I have not adjusted the valves yet but I doubt they would have changed adjustment so suddenly. I have not done a TBS as it is not running well enough to do so but at higher revs the twin max pulls evenly.

    I've been through everything and the only thing that eludes me and I don't think is normal is the weak spark. I get a weak yellow or orange spark from the plugs not a nice white or blue snappy spark like I would expect. The weak spark does seem to change in intensity from cold to warm, somewhat weaker when warm. The spark sometimes is more like static and dances all along the electrode instead of jumping at the gapped end. I'm leaning toward an intermittent HES. The HES was replaced 4 years and 30 k miles ago. I did pull the HES and peeled back the insulation to look for the deteriorated wires I had seen when I replaced it the first time. The wires seem soft and pliable with only the faintest hint of the green corrosion you see around electrical connections. The HES also seems ok by the fact that it causes the injectors to spurt and the plugs to fire. When the HES failed the first time the bike just died. This time the bike starts hard and runs badly. Would the intermittent HES cause the weak spark? I know the HES on these machines are troublesome can they fail after 4 years? Should I be looking for other problems?

    Other info; Two weeks and two tanks of gas before I had trouble I did replace the fuel lines, filter, etc. I opened it again yesterday just to see if I may have messed something up and it all looks ok.

    I do use these forums a lot for help and I do appreciate any help or insight you can give me.
    Last edited by bcusack; 05-27-2013 at 02:52 PM.

  2. #2
    Registered User m_stock10506's Avatar
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    WOW! Did you read my post on another BMW forum? I am in the middle of the exact same issue. First thing I did was check your location to see if you might have used the same gas station as me. Mine is a 2001 R1100RT with 105,000 miles. Same sequence of events. Running great; fill up at the end of my ride, then it won't idle and runs like garbage. I have replaced fuel lines and filter, fresh gas, good plugs. No improvement. My HES has never been replaced and never given a hint of problems - until possibly now.

    I will watch this thread carefully - let's share the fix if either of us gets there first.
    Michael Stock, Trinity, NC
    R1100RT, R100, R60/6

  3. #3
    Registered User roger 04 rt's Avatar
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    If either of you has, or can borrow a GS-911, there are a lot of things that can be ruled in or out. The process would be to attach the 911, select all realtime values, the LOG to CSV file. Start the bike, run for 5-10 minutes, examine the data and see what the input sensors are doing. If you get that far and would like it, I'd be happy to have a look at the files.
    RB

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    Registered User roger 04 rt's Avatar
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    And a follow up question, are you watching fuel flow in the return line going back to the tank or in the high pressure line coming from the tank?

  5. #5
    Registered User m_stock10506's Avatar
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    Both of our bikes are R1100RTs; I'm not sure how much data the GS-911 can get off of the R11 bike system. I don't have access to a GS-911.

    I am looking at fuel flow at the fuel injector. I have looked at it with the injector pulled out of the throttle body, and also with the fuel line unclipped from the injector. So I have seen fuel flow straight out of the fuel line, and fuel spray from the injector tip when the starter gets cranked.
    Michael Stock, Trinity, NC
    R1100RT, R100, R60/6

  6. #6
    Registered User bcusack's Avatar
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    Thanks Roger,

    In my case it is the return line to the tank, after the fuel distributor. I also get a nice even spray from both injectors.

  7. #7
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by m_stock10506 View Post
    Both of our bikes are R1100RTs; I'm not sure how much data the GS-911 can get off of the R11 bike system. I don't have access to a GS-911.

    I am looking at fuel flow at the fuel injector. I have looked at it with the injector pulled out of the throttle body, and also with the fuel line unclipped from the injector. So I have seen fuel flow straight out of the fuel line, and fuel spray from the injector tip when the starter gets cranked.
    I always forget that the GS-911 doesn't retrieve and log realtime values for the R1100. Thanks for reminding me. Having one wouldn't help that much now. If you do a search you can find out how to get the Motronic to read out its errors and there's also a TPS cal signal at the diag connector.

    Once you remove the injector from the fuel distribution the pressure is released and even with split hoses I got a pretty good stream of fuel. Injector spray was there but anemic. When you check the fuel flowing in the return line the pump and hoses have to be in good enough condition to force fuel past the 43 psi regulator. I'm not saying for sure that you have a fuel problem, just that you need to look at return flow to judge the system's integrity,

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