The fuel vent tube in my tank is partially clogged up. If I have a full tank everything is good, but once I get about 60 miles on the tank and I hit above 75 it starves out. In the process of determining that it’s the vent tube in my tank I’ve replaced the fuel screen, then the fuel peacock and check my vacuum lines. I also run an external fuel tank and when the bike starts to starve out I switch to it and the bike resumes to run fine as long as I shut off the peacock to the main tank. Earlier this month I made a quick run to Nova Scotia and it would starve out like clockwork at about the 60 mile mark when running on the freeway. It never once starved out in Canada, which may have something to do sea level and all that? When I got home to help to determine that the venting of the tank is the problem I took my spare key and popped the gas cap as I approached 60 and then ran it up to 80 with no problems. So here’s the question, how do I clear the vent pipe? I’ve run wire up as far as I can and put a length of hose on tube exit point and blew in it for a while and then ran some air through it with my compressor, with no improvement. I’m just about out of ideas. Thanks in advance for your help.
Fuel Vent Tube Troubles
1 - 17 of 17 Posts
Joined
·
2,236 Posts
Joined
·
48 Posts
So the issue with the vent is that it allows the tank to do two things:
when the fuel drains out of the tank it has to be replaced by air otherwise you get a vacum situation
Allows pressure to vent out from the tank when sitting in the sun
If the line is partially clogged you will get the issue you are talking about. Try disconnecting the line completely and running it. If you are still seeing the issue, check one last thing: the carb vent tube. It runs from the top of the carb to the front and down. Make sure that is not an issue as well.
A possible solution if the tank vent is actually plugged:
Pull the tank
drain it
flip the tank upside down and spray carb cleaner into the vent port. It might help loosen anything in there. I am not sure if there is a valve of some sort in there but if anyone knows that there IS NOT I would also recommend using compressed air to force out what was plugging it after using the carb cleaner to loosen it up. I used to have to use compressed air on my carbs on my ninja 500. Carb cleaner would loosen the gunk in the little ports then flush it out with compressed air.
(Note: this is only an idea and has not been tested. Its more of a SWAG than anything coming from my several years of working on bikes as I have never really run into this issue before)
when the fuel drains out of the tank it has to be replaced by air otherwise you get a vacum situation
Allows pressure to vent out from the tank when sitting in the sun
If the line is partially clogged you will get the issue you are talking about. Try disconnecting the line completely and running it. If you are still seeing the issue, check one last thing: the carb vent tube. It runs from the top of the carb to the front and down. Make sure that is not an issue as well.
A possible solution if the tank vent is actually plugged:
Pull the tank
drain it
flip the tank upside down and spray carb cleaner into the vent port. It might help loosen anything in there. I am not sure if there is a valve of some sort in there but if anyone knows that there IS NOT I would also recommend using compressed air to force out what was plugging it after using the carb cleaner to loosen it up. I used to have to use compressed air on my carbs on my ninja 500. Carb cleaner would loosen the gunk in the little ports then flush it out with compressed air.
(Note: this is only an idea and has not been tested. Its more of a SWAG than anything coming from my several years of working on bikes as I have never really run into this issue before)
As an afterthought my bike is idling faster than it has in the past. I ran a tank of carb cleaner through it and it might have cleaned things up and caused this but I thought I would toss that out there as well just in case it’s connected to my problem. It’s like telling the doc all of the symptoms to get the proper diagnosis. Thanks
Joined
·
2,236 Posts
Joined
·
12,243 Posts
Vent tube or petcock: 60 miles = 1.5 gals, less gas may not flow as well if the petcock has problems.
Vacuum diaphragm problem?? Check for gas flow when you apply vacuum..
California version with canister???
What about your fuel switch?? Check the flow through that from the main tank.
Not too many metal vent line problems. Any kinks at the tank nib? Any history of rust problem???
Vacuum diaphragm problem?? Check for gas flow when you apply vacuum..
California version with canister???
What about your fuel switch?? Check the flow through that from the main tank.
Not too many metal vent line problems. Any kinks at the tank nib? Any history of rust problem???
Joined
·
48 Posts
That is also a possible problem! The CA emissions! If you have a CA bike check out the removal howto.
Luckily it’s not the California version so that eliminates all those problems. I replaced the fuel peacock so I don’t think it’s that. 5.elements’s idea got me thinking that I might have a drop in vacuum under heavy load. What I could do is take the old peacock and override the vacuum shut off and put it back on to totally rule out vacuum related problems. There are no apparent rust problems. The inside of the tank looks new. When the problem started I took the tubing off of the vent pipe so that can be ruled out. Thanks for all of the suggestions. I will work my way through your ideas and see what happens. Thanks Again!
Done
OK, Tuesday night I drained the tank, turned it upside down and sprayed carb cleaner in the vent tube and let it soak. I also disabled the vacuum shut off on the fuel peacock. Last night I took it for a run and 80mph uphill no problems. On the second hill it did shut down, but then I realized that I only put two gallons of gas in and this time I was actually running out of gas so switched to reserve and no problems. Was it the cleaning of the vent line or vacuum disabling I don’t know and honestly I don’t care for now. I think this winter I’ll replace the vacuum lines and clean the vent line once more just for good measure. I can’t decide if I’ll reinstall a working vacuum shutoff or not, it’s just one more thing that could go wrong and leave me stranded. Thanks for all the suggestions and thanks again 5.element for the carb cleaner idea.
OK, Tuesday night I drained the tank, turned it upside down and sprayed carb cleaner in the vent tube and let it soak. I also disabled the vacuum shut off on the fuel peacock. Last night I took it for a run and 80mph uphill no problems. On the second hill it did shut down, but then I realized that I only put two gallons of gas in and this time I was actually running out of gas so switched to reserve and no problems. Was it the cleaning of the vent line or vacuum disabling I don’t know and honestly I don’t care for now. I think this winter I’ll replace the vacuum lines and clean the vent line once more just for good measure. I can’t decide if I’ll reinstall a working vacuum shutoff or not, it’s just one more thing that could go wrong and leave me stranded. Thanks for all the suggestions and thanks again 5.element for the carb cleaner idea.
Just an after the show thought.
When you had the tank off before, you could easily have trapped the overflow hose between the tank and the frame, causing this same problem. Then when you took it off to do the other work, it didn't get kinked.
Seen that happen more than once.
When you had the tank off before, you could easily have trapped the overflow hose between the tank and the frame, causing this same problem. Then when you took it off to do the other work, it didn't get kinked.
Seen that happen more than once.
Joined
·
6,252 Posts
On 2005 the Vacume hoses are old. !
Try blowing threw the tube going down the frame. Also place a small hose on the tank vent tube and blow into it. Also the T in the hose going down should not be plugged. If you can blow threw those lines then they are not your problem.
if you are using a auxilary tank and that is working fine then I would be looking at the Replacing the inside of the Petcock. you have the auxilary tank connected into the gas line going to the carb after the Petcock.
also if you hsve a bad or cracked vacume hose to the Petcock itt could partially close and restrict the gas flow. for $2 you can replace the Vacume hoses for a better quality hose. Vacume hoses on teas bikes have been known to go bad.
http://www.ronayers.com/ProductDetails/N/687/SKU/262400
Just things you might look at.
Donut
Try blowing threw the tube going down the frame. Also place a small hose on the tank vent tube and blow into it. Also the T in the hose going down should not be plugged. If you can blow threw those lines then they are not your problem.
if you are using a auxilary tank and that is working fine then I would be looking at the Replacing the inside of the Petcock. you have the auxilary tank connected into the gas line going to the carb after the Petcock.
also if you hsve a bad or cracked vacume hose to the Petcock itt could partially close and restrict the gas flow. for $2 you can replace the Vacume hoses for a better quality hose. Vacume hoses on teas bikes have been known to go bad.
http://www.ronayers.com/ProductDetails/N/687/SKU/262400
Just things you might look at.
Donut
That’s a great idea; I’ll add an elbow when I replace the vent tube. I also agree with going with better quality vacuum lines. My auxiliary tank is plumed into the gas line after the peacock with its own shutoff, so it totally works independently from my main fuel tank. The auxiliary tank is mainly for out west where gas stations aren’t as plentiful on the secondary roads and for highway running. It gives me about an extra 100 miles. For this problem it was priceless.
1 - 17 of 17 Posts
Join the discussion
Join now to ask and comment!