Bonneville America Forums Forums Technical Forums General Tech Fuel where it oughtn't be

Folks,

After scratching out what's left of my hair, I'm going to ask for help. What would cause fuel to pool up in the airbox of my '06 America?

A little background: at the end of April I started it up for the first time this season to take it to the shop for inspection. It ran great even after sitting since October, no problems. Being the fool I am, I negelcted to turn off the fuel valve when I got home.

A month later (May 22) I go to ride it to work and it starts hard, won't idle unless I hold the throttle, and has no power. I thought it might improve as it warmed up, so I took off with it. I get about 4 miles from home and it quits completely; I need to call a tow truck to get it home. (It was my birthday and I darned well wasn't going to push it home.)

That weekend I thought I'd check the air filter since we'd had a lot of windblown fluff in the air from some trees in the neighborhood. I thought it might have clogged the filter. When I removed the air screen, the airbox was full of fuel. I siphoned out about a pint and a half.

Any ideas?

Dave

Sounds like you have a stuck float.
Before you start the bike again INSPECT THE OIL!
If that much fuel got in the airbox, it could have
gotten in the oil as well.

Changes in temperature will make the fuel expand and contract. As the fuel in the lines expands it'll push past the needle valves and into the air box. Get into the habit of turning off the petcock when leaving the bike for more than a a day or two. It also wouldn't hurt to check the needle valves for wear or dirt.

FYI you don't need to siphon out the air box, just take the rubber plugs off the drain tubes below the bike.

Folks,

Thank you for the suggestions. I'll be sure to check the oil for fuel contamination.

Dave

Folks,

Now I'm stumped again. I've had the carbs off twice: checked & cleaned the needle valves, seats, and floats; measured the float height per the service manual's instructions (both carbs spot on); and tested the carbs on the bench to make sure fuel stops flowing when the bowls are full. But when I put the carbs back on the bike fuel still overflows.

Rather than wait for fuel to appear in the airbox I've been testing with a clear tube attached to a carb bowl drain. When I turn on the petcock the fuel in the tube rises clear up to the side of the fuel tank.

I'm open to suggestions no matter how crazy. I can't afford to send the thing to the shop. Any ideas?

Dave

Could it be the angle at which they sit on the bike is just at the wrong spot causing the floats to not close the float needles? Those float needles are tricky sometimes. They might even need to be replaced. I know you said you cleaned it, but even the tiniest piece of fiber can cause problems at the float needle seat.

But the needle valves closed just fine while I had the carbs off the bike. That's what has me confused.

One thing I wondered about while I had it apart. Are the tips of the needles supposed to be black? On both needles the tips are a flat black color from the point up almost to the rim of the cone. It's a very even coloring, so I assumed it was intentional. The rest of the needles are silvery metal.

One other thing - how do I get the valve seats out?

Dave

I found the cause for my fuel flooded airbox. It was the carburetor bowl vent tube. It looks like mud daubers tried to build a nest in the end of the rubber tube where it hangs near the ground, clogging it. I popped the tube off of the vent nipple between the carbs and tried the fuel level check again, and it's just a whisker above the edge of the bowls on both sides.

So now all I have to do is check the cylinders for gas buildup, change the oil, replace the air filter, unplug and reconnect the vent tube, and I should be back on the road.

Thanks for your help, folks - I don't know what I'd have done without the forums here.

Dave

Thanks for the update Dave. Glad you got things sorted out.

Okay, Book 2 of the saga. (I hope this isn't a trilogy.)

Cleared the bowl vent, changed the oil (very thin and a lot of it - thanks for suggesting it, unclecharlie), checked the cylinders for standing fuel (they were dry), replaced the air filter, charged up the battery and started it up. It caught and idled just fine, no surging or popping.

Saddled up and took a lap around the park to see if it'd keep running. I could feel more vibration from the engine than I remembered, and it didn't have any power. It tried to stall taking off from a stop a couple of times. I took it up the street to get fresh gas and could barely make 40 mph. On the trip back it would surge and backfire frequently, on the left side, with or without choke.

In the course of looking for the original fuel leak I had replaced both float needles. I had never checked the bowl fuel level before this started, but with the new needles and a clear vent both carbs level out about 1/8 inch above the line where the bowl mates to the carb body.

When I checked the cylinders I noticed both spark plugs had a dry sooty appearance, but not heavy.

After removing the carbs about three times over the summer, I noticed the cement where the rubber boots attach to the airbox has pulled free. Without pulling on the boot you can't see it, but if you twist or pull on the carbs you can see the shoulder of the boot pull away from the airbox slightly.

So far I'm planning to put some carb cleaner (Sea foam if I can get it) in the fuel tank and replace the spark plugs. Is there anything else I should look at or try? Would the lack of a glued seal on the airbox boots allow enough air entry to behave like a vacuum leak? How about if an airbox drain plug is missing? (They were really slippery when I took them out to drain the box a while back.)

Dave

I found it. Fouled plugs and a misadjusted throttle cable that wouldn't let the throttle return to rest against the idle stop. Two new plugs and a couple of twists with a wrench (and half a can of Sea foam for luck) and I'm back on the road.

Dave