1150GS - noisy fuel pump/spluttering at half tank

Discussion in 'GS Boxers' started by Flys Lo, Jan 24, 2013.

  1. MsLizVt

    MsLizVt pfft ...

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    Flys Lo et al, hi!

    Your dilemma is exactly what mine was a two years or ago. My 1100GS would run fine until mile 122. Well it might have been a few miles either way, but that was the number that stuck in my mind. From a full tank to about that mileage the bike would run great. Then all of a sudden it would stutter, hiccup is more like it, just stop running for a few seconds. When rolling back on the throttle it would go again.

    The first time it happened was on a three hour ride, a bit time critical to make it to an appointment. For the last 50 miles, it would hiccup every couple of minutes. After the appointment, the bike came apart, tank off, seat off, panniers off, just about everything, looking for wiring issues, and leaks. With all the parts and my gear strewn around the parking lot it looked like I was having a yard sale! After fiddling with everything, it all went back together, and I filled up with gas. On the ride home, at mile 122 it hiccuped! Filled the tank and all was good again.

    At home everything came apart again. This time, the fuel filter was changed. The old one looked great, but a new one went on. Rode around, the bike ran fine ... until about 80 miles on a tank and going up the steep passes of the mountains here in Vermont, and it hiccuped again.

    Oh, when the tank came off at home, many of the various things suggested above were done also, including putting compressed air in the vent line. There's a lesson to be learned from that. Inside the tank, near the filler is a container that one of the vent lines goes into. It's got a pin hole vent in it. At 160psi, that little 2 inch by 3 inch by 1 inch hollow unit make the loudest bang I'd heard all day, and split in half.

    That came out of the tank by taking the filler off. When seeing it was split along the seam, longitudinally, my first thought was superglue or epoxy. Being in gasoline all the time, that probably wasn't a perfect idea. So in addition to epoxy, using a fingernail file, I put notches on the outside edges. Then from the days of rally cars, there was some fancy wire and spinning pliers around, that we used for wiring nuts and bolts. a wrap of that wire, tightened down with the spinney pliers, made that little hollow thing I'd blown in half, pretty secure.

    Okay, back to climbing the mountain passes and the bike hiccuping. All the way up to the top, it would hic every couple of miles. On the downhill side it ran fine. After being fueled up, all was good.

    Oh and trust me, I read every thread on ADV that had anything to do with fuel pumps and gas tanks. Finally, I ordered one of the Bosch 6222 pumps (off the top of my head, that might not be the correct number) that went in a 1992 Chevy Something or Other, for $50. When it arrived, carefully the soldering was done, and everything put back together.

    That was two years ago, and something like 40,000 miles, not another hiccup since.

    Here's what I think. One thing that I did was put a fuel pressure gauge inline. When the key came on, the fuel pressure would go up to 42pounds, maybe it was 43, but something like that. And a couple of moments later it would go back to zero. In my mind, it seemed to me that once the pressure was up, it should stay up, but it didn't. And honestly, I haven't been able to find anything that says it should stay up at 42. Shouldn't there be a check valve in the pump? Any thoughts from those in the know would be appreciated.

    My belief is the pump was staying cool as long as it was in gas. When the tank got below the 122 mile level the pump was exposed to the air, and would overheat. My guess is the pump in the bike was the original one, with 80,000 something miles on it. So it served it's time.

    My plan (which hasn't been done yet) was to dissect that pump to see if any brushes inside were worn way out, or there was something wrong with the windings, or a bearing was gone, or just see what was in there. Maybe it was something to do with the impeller slipping on the shaft, who knows. But from your description, it sounds just like what happened to me.

    How's that for a rambling thread jacking (good story def?)? Am I making sense?

    Enjoy,



    Liz
    #21
  2. roger 04 rt

    roger 04 rt Long timer

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    Hey Liz, good story. We nearby flat landers love the neat mountain passes of Vermont. To some questions and good points you made:

    —The thing you blew apart is a check valve to keep fuel from running out when/if the bike tips over. Who lets that happen? ;)

    —The fuel pressure will stay at around 40 PSI after a couple seconds on, even after the key is off (photo below, motor and key off).

    The stock pressure for 1100s and 1150s at idle is 43.5 psi in the line going from the tank to the fuel distributor, and the return rate in the line going from the distributor back to the tank at idle is 1/2 gallon per minute. If you check both you have a good idea of the health of your fuel system. Measuring the return volume is more important than pressure since the regulators are pretty bulletin proof.

    RB

    [​IMG]
    #22
  3. roger 04 rt

    roger 04 rt Long timer

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    You are special, but won't be forever. Find out where your system is clogged now and you'll avoid a breakdown later.
    #23
  4. Jim Moore

    Jim Moore Long timer

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    I highly recommend you get rid of your canister and vent the tank line to the atmosphere.
    #24
  5. roger 04 rt

    roger 04 rt Long timer

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    I still have my canister and the system is working fine. Why do you recommend removal?
    #25
  6. def

    def Ginger th wonder dog

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    Oh my.....The charcoal cannister thing is almost like aftermarket exhaust systems and motor oil...Heh-heh.

    :lurk
    #26
  7. def

    def Ginger th wonder dog

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    Excellent idea. I would be tempted to do this also once I go into the tank.
    #27
  8. mouthfulloflake

    mouthfulloflake Not afraid

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    I cant claim the idea, someone else on here did it, and I copied the idea!

    nice brake bender tool, and a 36" section of hard line was about $15, so cheaper than the bmw part, should last at least as long ( likely longer) and I got a brake tool to boot!

    there was enough hard line left over to bend a few more if I can find it in my mess of a garage Ill bend you up a U and send it to you.



    #28
  9. Jim Moore

    Jim Moore Long timer

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    I was talking to the guy who is having tank venting problems. But hell, take yours off too. They get clogged up and cause problems eventually. And they're ugly.
    #29
  10. MsLizVt

    MsLizVt pfft ...

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    Roger, hi!

    Thanks for the compliment about the story. It was Brandon Gap, going from Rochester to Brandon when the bike was hiccuping. All the way up I just kept making promises to the bike to never do anything bad to it, and wash it when we got home, as long as it got me over the top of the gap. Of course the bike did get over the top, and I didn't wash it. But with the new pump, it keeps on going. We have some pretty cool gaps/passes up here, especially Lincoln Gap on a foggy night. There's another story to go with that evenings experience too.

    So you answered one of my big questions about the fuel pumps and fuel system. With the old pump, and a gauge set up, just about like you have there, when the key went on, the pressure jumped right up. But even with the key on, after a few seconds the pressure would go back to zero. So where's the check valve in the system that keeps the pressure up, in the pump?

    The other question is, what could get so hot in the pump to make it malfunction when hot, brushes? bearings?

    Thanks, and come on up and ride sometime. I'm in Rut-Vegas (Rutland) next to the Vermont State Fairgrounds. Send me a PM and I'll give you the GPS data.

    Enjoy,


    Liz
    #30
  11. everycredit

    everycredit Been here awhile

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    I have no canister and my fuel system is working flawlessly (sans canister).
    #31
  12. roger 04 rt

    roger 04 rt Long timer

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    You're going to have to open up your tank and look.
    #32
  13. Jim Moore

    Jim Moore Long timer

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    Well, it's not working flawlessly. Something is creating a vaccuum in your tank. Since you have no canister I'll bet your vent line that used to go to the canister is pinched or clogged. Those lines are pretty easy to check, and easy to replace if there is a problem.
    #33
  14. Steve W.

    Steve W. Boxer Pilot

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    #34
  15. roger 04 rt

    roger 04 rt Long timer

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    Yup, but at this point there are 34 replies and ideas for Flys Lo. Seems like he's got plenty to work with when he eventually gets around to opening his toolbox.
    #35
  16. vintagerider

    vintagerider Long timer

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    Roger, great pics. References to the fuel spider are numerous. Rarely depicted are the invasive tendrils of its web concealed within the system. If evap lines seem clear, then one can open the seams on the evap kanister to check for egg sacks. Three grams of shaved naptha inside old tea bag taped to the throttle plate during storage may discourage nesting in the first place.
    #36
  17. def

    def Ginger th wonder dog

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    I would be forever in your debt. But, maybe we can save some postage...I do get to Branson from time to time and that's not too far from NW Arkansas ....say Rogers, Bentonville? About 80 miles....and the ride would be very picturesque. All I would have to do is avoid all the Wal-Mart trucks.

    Wow...Bentonville is nothing but Wal-Mart trucks every where and that was from my last travels there, about 25 years ago...its even bigger now, I'm sure.
    #37
  18. everycredit

    everycredit Been here awhile

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    No, it's fine.
    #38
  19. vintagerider

    vintagerider Long timer

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    Liz and Roger have good advice. The fuel system isn't that complicated. Those who take the time to disassemble, clean and inspect are rewarded. The OPD (overflow protection device) is combined with the tank vent which in turn may incorporate EVAP (kanister). Washing the tank isn't hard. I use warm soapy water followed by alcohol rinse. Several plumbing mods are possible. Newbies: review list of precautions before you begin i.e do not strip the tank studs. It never pays to do a partial tank service. All the ports need to be cleaned, pump impeller fins checked ect.

    Out here our fuel spiders are venomous; maybe not for your region. Discuss any external fuel filter mods with Def. Apparently some fella in N Carolina burned down the drive-in then the conflagulation spread to the mayor's house. I put my filters in the steer head hollow, great for me but too many are gonna run the hose close to the exhaust. It's kinda hard to see where your going at 70 mph with a fireball up front and your groin on fire.
    #39
  20. Flys Lo

    Flys Lo cool hand fluke

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    Thanks for all the further responses. Hopefully the parts will be here from Beemer Boneyard early next week, so the following weekend I should be able to take the tank off and go to town. Based on what I have read here, it sounds like it is one of the lines in the tank probably has a hairline crack, and when the fuel gets down to a certain level (i.e. the fuel line is no longer submerged), it gets air in the line, and after that, the fuel pump has to work a lot harder to maintain pressure, hence the increased noise.

    That's all an educated guess anyway.

    Still, a good opportunity to replace the fuel pump/everything else anyway.
    #40