2004 Fatboy, carbureted. Hasn't run in a while but got it started and running a few weeks ago. It ran poorly so I ordered a carb kit and figured I would just do the bottom of the carb because I want to sell the bike. Changed the float, accel pump, etc and went to start it. It ran a bit and then stalled and then fuel/oil mix came gushing out of those little black tubes from the head vents. Probably 2 cups easily. So I pulled the whole carb and did a rebuild, put it on and the same thing. Checked the oil tank and it clearly is fuel/oil. Not really sure where to start trying to figure out how I am getting so much fuel into the oil.

Kind of thinking I need to drain the oil and refresh and see if maybe the full carb rebuild has fixed whatever cause so much fuel to get into the oil. But I don't really want to spend $25 on good oil if I'm going to be throwing it out again because something else needs fixing. So any ideas on how the fuel filled up the oil tank?

Thanks

 

Do you still have the original fuel petcock valve? That should not allow your engine to fill with gas. It it has been changed, then your float needle is not settling and allowing gas to flow directly into your engine.
Good luck

 

Thanks - another friend suggested the petcock. I guess there is a valve in there that might have gone bad and will allow fuel into the engine. I'll check it out and see what is going on.

 

Well, even if it flows gas, it still shouldn't fill the engine. I had that happen once on mine and I had a piece of dirt blocking the float needle valve and the valve stayed open until the gas was gone.
I would start there for sure. Carb off and some carb cleaner and you might be good to go.
Good luck

 

In 2004, the fuel petcocks (#61338-02) were vacuum operated. They are not supposed to flow fuel without vacuum from the carb on an engine that is cranking over, or running. They have a diaphragm with a hose to the carb for vacuum. The diaphragm or hose can deteriorate and allow the petcock to lose vacuum. They are known to fail or have issues..

But whether the fuel petcock is working or not, it is a backup, or failsafe, in case the float valve doesn't stop the flow of gas into the carb. The float valve if operating properly, will stop the flow of fuel when the float bowl gets full, even if the petcock is open... On my old shovel, at first, I would often forget to close the manual fuel petcock (no vacuum system) and never had gas flow into the engine. Luckily I learned to use the petcock and it became second nature..

While fixing the fuel petcock is good and necessary, making sure the float valve in the fuel bowl is working properly, is even more important...

You say you rebuilt just the bottom half first, with the carb on the bike.... . It would be really hard (I know I couldn't) to properly set the float valve and clean the float valve seat, with the carb on the bike.. Did you disassemble the whole thing when you removed it and reinspect and reset the float valve/seat? If not, I would say that shoiuld be high on your list. If you did, I would remove the carb again and check your work, as gas won't flow through a carb with the float valve working properly...

You definitely need to change your oil... Fuel in the oil greatly reduces its lubricating properties. And oil flowing through the carb, into the cylinders, and then down into the sump, will wash the cylinder walls of all oil, causing increased and premature wear to the cylinders and rings...

Good luck with the repair...