On the way to work today I experienced my 2005 Shadow Spirit sputtering and eventually cutting off completely. Upon trying to start the bike up again I noticed fuel pouring out of the carb vent tube and exhaust pipe. Had it towed home and left for work. I came back at the end of the day and fired up the bike, no more fuel was spewing out. I went ahead and pulled the carb out to inspect the float and didn't find anything unusual. Any ideas on what may have caused this issue? Some things to note, I have rebuilt the carb earlier this year and the float needles were replaced, also float height was set to 7mm as per the service manual. Any help is appreciated, thanks.
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VT750DC Fuel Pouring From Exhaust
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TJ Admin Staff memberModeratorMember who has the rights to delete posts, and ban members form forum if they violate the rules.@Alexander Alonso if fuel was pouring out of your exhaust you washed your cylinders. This means the fuel stripped the oil coating from the cylinder walls and there is likely fuel in your oil. before you ride more, you should pull the fuel dipstick, and smell the oil if you get a hint of fuel, you need to flush the oil and replace the filter.
So heres what the issues could be with fuel coming out of the exhaust and vent tube:1. The Float. Its either stuck, or jammed, or theres crap in the seat. preventing the rubber tip from closing off the path of fuel. or youve got the incorrect float height.
2. Petcock for Fuel pump failure. the petcock may just be dumping fuel into the carbs even if its closed. or the pump is overpressurizing the carbs.3. The Needle Jet or emulsion tube are missing. If the needle jet is installed upside down or not installed at all, you got a problem, if the needle isnt held in by the retainer inside the slide, the fuel will just blow out of the emulsion passage. the emulsion tube may not be seated and just hanging or sitting in the bottom of the bowl.
Now some less common issues, The intake valve isn't closing that means fuel mixture will basically blow back out the carb it can push fuel out of the carb vent and the air box it allow raw fuel to pass through the exhaust it's usually a company by backfiring through the carb and you'll have low to no compression on that cylinder where the intake valve isn't closing
another less common thing might be that the there's timing or spark failure so fuel keep going into the cylinder unburned the unburned fuel then push in the exhaust pipe the excess fuel is going to go back through the carb on the overlap cycle of the valves opening yeah you'll get zero ignition on that cylinder if you're not getting any fire
now here's a severe possibility this is pretty rare you'll have a stuck or a worn piston ring so up completely dead cylinder can allow fuel to just pass right through it without resisting it that's usually accompanied by low compression hard starting and your oil is going to smell like gasoline now the most likely cause that based on your symptoms and what little you told me about the history of the carburetor and bike is that it's a stuck float or a leaking float needle causing massive carb flooding this is the only failure that really easily explains fuel coming out of the car then and fuel exiting exhaust Port both due to the cylinder filling with raw gas so it's basically like a toilet with a stuck float the ball just never stops feeling and everything just keeps going Downstream
what's super important is that you do not run the engine till this is fixed cylinder flooding can cause three symptoms hydrolock which results in a bent rod and destroyed engine engines done this will also result in oil dilution which means there's fuel in your oil and it can cause a fire in your exhaust so hopefully this helps you sort things out but please don't run the bike till you solve this issue
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@TJ this is a butt load of info but appreciate you taking the time to help. I'll for sure change oil and filter to start and go from there. Initial inspection of the carb didn't provide any clues. As of recently the bike has been running great, carb was rebuilt in March with the performance kit, I set float height to spec "7mm" The float showed no signs of being jammed or hanging up but I will double check for anything preventing the float needles from properly seating. As much as I love riding this bike it is requiring more time and attention than my wife.
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