When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
All, Im new to the site and looking for some help. I have a 2016 Fatboy S and if I fill it to the top with fuel, I lose 1/3 of a gallon thru the FUEL VENT TUBE. It flows from right in front ofthe rear tire (not at the tank valve). First, does anyone have this issue? Second, have you found a fix? Third, what I am thinking. Can I plug it at the tank and modify the fuel cap to vent both ways.
Last edited by Echo9; Apr 29, 2023 at 02:41 PM.
Reason: Moved picture
All, I’m new to the site and looking for some help. I have a 2016 Fatboy S and if I fill it to the top with fuel, I lose 1/3 of a gallon thru the FUEL VENT TUBE. It flows from right in front ofthe rear tire (not at the tank valve). First, does anyone have this issue? Second, have you found a fix? Third, what I am thinking. Can I plug it at the tank and modify the fuel cap to vent both ways.
That is not normal.... something is amiss.
I always top off my bikes. I currently own four Harleys, two of which are Twin Cam Softails, and none of them have ever done that...
You'd do better to figure out what the problem is and fix it... rather than re-engineering the vent system to avoid a repair....
Is your bike new to you or have you owned it since new...?
Was it working fine and this just started....?
Have you done any recent maintenance, repairs, or mods to the bike....?
Is this a CA model or a 49 states model...? They have different fuel tank vent systems.
Last edited by hattitude; Apr 29, 2023 at 09:31 PM.
Wow - you better not blow yourself up ! As above - something is really wrong - OR you are massively overfilling the tank. There should be a rim about 1 to 1 1/2 below the gas cap and it should have a small hole and the nozzle hole. Don't keep pumping gas above that.
Inside of the tank, should have only one vent overflow line at the front of the tank, and depending the state emission package, it either goes to the atmosphere or a catch when overfilled.
Many of the fuel tank vent lines, in non CA models, have a "vapor valve" somewhere in the vent line. On a 2003 Heritage it has a separate part #62150-85. On the OP's bike, it appears to be at the end of, and part of the vent line itself: Vent line assembly #61100001 @ $31.81
That vapor valve should allow vapors to be released, but act as a siphon break to avoid the OP's issue...
In CA models the fuel tank vent goes through a charcoal canister, and has a purge valve, to avoid the fumes from being released into the atmosphere....
I would suspect, at the least, the OP's vapor valve or purge valve (if a CA, CARB emissions model) is failing.... That is barring any current work, or mods that could have affected the fuel tank/vent function...
To add to Mr. H.
Yes, they have a one-way valve, which some refer to as a Roll-Over-Valve. I do not see how that could have the fuel pouring out at the rate he has. That valve is in the hose that is what we think of as the vent line/overfill line.
That looks like it is a 100% free-flowing stream of fuel. When one-way valves become clogged or restricted it usually results in a vacuum lock condition by not venting the fuel tank. That would be where he could fill the tank past the overflow port and to the very brim and nothing would be coming out of the line he is showing.
Unless but I doubt, he has a CA charcoal canister and it is full? But still, that flow he has is major free-flowing fuel.
Last edited by MarlinSpike; Apr 30, 2023 at 09:53 AM.
OP; How saavy are you with repairs, or wrenching on bike? If not - take it into dealer for a look/fix as you're about to become a new superhero (Ghost Rider 2).
If the OP answers my questions in post #2, we can make a more educated guess.....
But with that high flow of fuel coming out as he shows in the pic... I would suspect that someone had, or thought they had, tank vent issues, and just replaced the entire vent line with an unrestricted section of fuel hose...
Last edited by hattitude; Apr 30, 2023 at 10:58 AM.
Thanks everyone for the response. The bike is new to me and not a CA model. Bone stock when I got two months ago with only 1,500 miles on it. Since I got it I have done a three hole service, installed pipes (not slip on’s), and buffed the entire bike.
I only fill to the bottom of the filler neck, and like I said, I lose 1/3 of a gallon and it stops. My fear is it gets a Venturi effect one the road and pulls fuel at speed.
Wrenching is not an issue for me but wanted to get some opinions.
Thanks everyone for the response. The bike is new to me and not a CA model. Bone stock when I got two months ago with only 1,500 miles on it. Since I got it I have done a three hole service, installed pipes (not slip ons), and buffed the entire bike.
I only fill to the bottom of the filler neck, and like I said, I lose 1/3 of a gallon and it stops. My fear is it gets a Venturi effect one the road and pulls fuel at speed.
Wrenching is not an issue for me but wanted to get some opinions.
I'd start by doing a close inspection of that Fuel Vent line & vapor valve....
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.
Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.
Slideshow: Harley-Davidson's challenges aren't abstract; they show up in dropping shipments, shrinking dealer traffic, and strategic decisions that aren't yet translating into growth.
Fatboy fuel vent tube leaking
