2001 Sportster Carb Overflow Leaking

[SharkenBeard]

Morning guys, I built a hardtail Sportster last year. My OEM petcock with the vacuum line was causing issues so I replaced it with a gravity feed petcock. Rode it all last year and a few months this year with no problems, when all of a sudden I noticed fuel leaking out of my overflow line while I was fueling up. I hadn't turned the petcock off since I was just getting fuel, I never have before. So I finished, fired the bike up and as I was riding I see it's still leaking quite a bit of fuel, enough to see it while I was riding? I figured it was the needle on the float in the carb not seating or worn out. So when I got home I removed the lower part of the carb, and replaced the plunger part on the float. That fixed the issue. No more fuel leaking while running, everything was good.

So flash forward to yesterday, fueled up on my way home, parked the bike and promptly forgot to close the petcock (I'd had a few drinks and that wasn't on my mind apparently?) When I got up this morning, there was a puddle of fuel under the bike and the overflow line was leaking. Part of me says well no kidding there is, you had a full tank and left the gravity feed petcock open?? But another part of me says that might be a sign that something else is worn out? What is everyone thoughts?

[Hoghead]

I one got a siphon effect on an '88 1200 sportster when the cap vent inadvertently got blocked. Gas pissed out of the carb-there was nothing intermittent about it though and I certainly didn't try running it! You sure the carbs clean inside?

[SharkenBeard]

The lower half was cleaned out last week. But honestly I need to pull the entire thing apart this winter and fully clean and rebuild it.

[Tattooo]

It sounds like you have trash in your tank and lines......

I hate inline filters but do you have one??

[SharkenBeard]

No I don't, that's a good point. I hate the look but obviously they are important. So I need to do a full clean/rebuild and add an inline filter.

[Tattooo]

No I don't, that's a good point. I hate the look but obviously they are important. So I need to do a full clean/rebuild and add an inline filter.

Like I said I hate filters all they do is slow down the gas flow.........

If it were me I would take the tank/petcock off and clean the hell out of them..... Replace all the lines and clean the carb really good...... And forget about the filter......

[SharkenBeard]

That's good to hear, because after looking at the space I have, I'd have to get creative fitting one in there...I agree, I'll take the tank and petcock off and clean the piss outta them. Same to the carb, and see what happens. Thanks

[brooklynbomber]

Have you changed anything else like the fuel cap when you did the Percocet change? Is your tank vent properly connected? Is your cap properly venting?

[Tattooo]

Have you changed anything else like the fuel cap when you did the Percocet change? Is your tank vent properly connected? Is your cap properly venting?

I would think it's vented just fine since it's over flowing, But I could be wrong......

[SharkenBeard]

No change to the fuel cap, and yeah I replaced the vent line when I built the bike last year.

[Skjoll]

... causing issues so I replaced it with a gravity feed petcock. Rode it all last year and a few months this year with no problems, when all of a sudden I noticed fuel leaking out of my overflow line while I was fueling up... I figured it was the needle on the float in the carb not seating or worn out. So when I got home I removed the lower part of the carb, and replaced the plunger part on the float. That fixed the issue... So flash forward to yesterday...there was a puddle of fuel under the bike and the overflow line was leaking...

What 'overflow line' are you talking about, the float bowl overflow or the fuel tank vent hose? It sounds to me that it's the carb's float bowl since you mentioned the float valve (needle) and that fixed the issue the first time around. If it's indeed the float bowl overflow then clean the carb, if there's evidence of contaminants then that could prevent the valve from closing. Get a good mesh inline fuel filter, they flow more fuel than the motor can ever burn (1 gallon in less than 3 minutes). If all is clean then replace the float valve again. I've seen new ones go bad pretty quickly when the owner used an ethanol blend fuel. My red Sporty got her nickname (PeePee) because of a bad float valve.

[brooklynbomber]

I would think it's vented just fine since it's over flowing, But I could be wrong......

If it’s not venting, it can build pressure In the tank and force fuel out the carb.

[Tattooo]

If it’s not venting, it can build pressure In the tank and force fuel out the carb.

I guess it could happen, I've never seen or heard of it before...... But if it did you would still have a needle and seat problem not a vent problem.... But like the OP said that's not his problem......

[industrialmarshmallow]

Is your drain screw 100% tight? I kind of doubt that's the issue since it's intermittent,but it's worth a check.

[devthtrip]

i just had something similar where my carb was pissing gas. doubt it’s the same but the screw directly behind the mixture screw split it’s o-ring. threw a new one on and no problems since