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Help. Fuel flow problem!!!!

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    Help. Fuel flow problem!!!!

    OK, we have the bike running great but all of a sudden we are getting a fuel flow problem. Turn on the petcock and it fills the filter and allows fuel through. Hit the road and either you ride for an hour with no issues or 10 min in you stall out with a dry filter and no fuel. open the tank, nothing changes, pull a fuel line and fuel starts flowing all over and your ok to ride again, sometimes for an hour sometimes for 10 min again. I cannot figure out what the hell is going on. I bypassed the fuel pump and it still does it. The petcock is clean. Shining a flashlight into the F2 tank and you can see it nice and clear. if it was plugging it wouldn't just start flowing as soon as you add air to the fuel lines. I'm at a complete loss and cannot figure out what is causing this. It has been in the 95-105F temps? not sure that is an issue or not. Help please we are about to do our first trip and stopping every 30 miles to restart fuel flow will suck on a 360 mile ride.

    #2
    maybe the fuel line is collapsing when it heats up?
    Brian - Richland, WA
    1991 Hawk GT
    1997 VFR

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      #3
      Originally Posted by bk94si View Post
      maybe the fuel line is collapsing when it heats up?
      I don't think so but I can change the last piece from filter to carb. Thing is I road it for 65 miles in 105F and had 0 issue, then next day it went 15 mikes and stalled out in 75F temps. It's super weird. It's air locked but in no way consistant. We're leaving for the trip and will deal with it but I'd love to sort it first.

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        #4
        Is the bowl vent clogged? Sounds like a possibility.

        Tank vent not working?

        One of those is likely i would guess.

        Stock fuel pump or vacuum? I had a bad vacuum line connection point at the rally this weekend. Could not figure out why there was no fuel in the front bowl.. Took is 4 carb cleaning / rebuilds to diagnose. Had a fuel line that was kinking once on the way home from a rally... Couldnt tell when the tank was on, and tank off uncrimped it..


        Don't spend money and buy, spend time and learn.

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          #5
          It's original pump. I'll look at carb vents. That makes sense. Tank vent isn't it as even open the fuel doesn't flow until you take a line off and put back on.

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            #6
            bowl vents are where on these carbs? I was starting into the manual but we spilled gas all over it and the pages are now hard to read. I need to download and reprint it but is someone can point me to where they are I can check for blockage. Carbs were clean as a whistle when I re-jetted them last though and always run with a filter.

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              #7
              ok so I found the digital version of the book. I removed the hoses on the vents but I should put them back on and see if that fixes the issue.

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                #8
                Originally Posted by Maritime View Post
                ok so I found the digital version of the book. I removed the hoses on the vents but I should put them back on and see if that fixes the issue.
                I don't run hoses on them at all. But as long as nothing is clogged or looped and they vent to open air, you should be good.
                Don't spend money and buy, spend time and learn.

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                  #9
                  Home now. Checking everything and packing. Leaving earlier to beet some rain coming in.

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                    #10
                    Alright did 130ish miles and it needed help 2x to start flow then it ran 60-70 miles without a hiccuup. 2 fuel stops, one lunch. Check stuff all looks correct. It's so intermittent not sure it will be easy to find. 240 miles tommorow. 10 hours to get there. Should be ok.

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                      #11
                      this is an f2 tank?
                      Don't spend money and buy, spend time and learn.

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                        #12
                        F2, harley pcock. Day 2 had some issues but we covere the 468km. 280 miles mostly back roads. Had to burp air about 6 times. Random distance and speeds. We have a garage to work in here at my sisters. Will sort more tomorrow before riding home Friday. I however need a front tire and killed my battery on a fuel stop. Bumping the 79 GL1000 is so fun. On a charger now in hopes it can be saved.

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                          #13
                          Are you using a fuel pump or is this gravity feed?
                          Don't spend money and buy, spend time and learn.

                          Comment


                            #14
                            Fuel pump is fubar. Been gravity feeding and have done over 600 miles. Bike runs great until it doesn't then we burp the line and boom back to hauling ass. We got a replacement pump from PO who swung by with a spare part bin. We are at my inlaws and will swap out the oem pump with the china bay one and see if it works. Also I found the actual float bowl vent hose and it was clear but will blow the actual nipples out too. Have time tomorrow to sort a bunch before the last 120 miles home. Trip has been a lot of fun, Magoo asked, "Can we take this to a track?" Next father son thing to do! Once fueling is fixed.

                            Comment


                              #15
                              Originally Posted by Maritime View Post
                              Fuel pump is fubar. Been gravity feeding and have done over 600 miles. Bike runs great until it doesn't then we burp the line and boom back to hauling ass. We got a replacement pump from PO who swung by with a spare part bin. We are at my inlaws and will swap out the oem pump with the china bay one and see if it works. Also I found the actual float bowl vent hose and it was clear but will blow the actual nipples out too. Have time tomorrow to sort a bunch before the last 120 miles home. Trip has been a lot of fun, Magoo asked, "Can we take this to a track?" Next father son thing to do! Once fueling is fixed.
                              Hehe.

                              That's how it starts.

                              $30,000 and 5 years later and you have a pretty capable racer on your hands.


                              No one goes to college any more any ways.

                              Edit: that $30,000 may be a conservative estimate... But I like to look at what I spend racing through the rose tinted glasses of denial..
                              Last edited by 6; 08-06-2022, 12:34 PM.
                              Don't spend money and buy, spend time and learn.

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