Consequences of Overfilling Fuel Tank

old · 10-31-2012, 06:42 PM

What bad things happen when this is done? I live close to gas station, fill my tank when returning from a ride. With bike on side stand, I can't seem to keep from filling the tank slightly above the bottom of the inner neck. Had one incident during the summer where fuel leaked thru the carbs.........my theory is the heat caused a pressure build (tank could not vent) up within the tank, and the petcock allowed fuel to flow to the carbs, which also could not contain the extra pressure. Opinions?

Gary W. · 10-31-2012, 07:32 PM

This is just an opinion....I would think with the cool weather now you shouldn't have any issues with expansion and leakage. If you're worried, you could always just ride around for another 20 miles or so to lower the level.

PI Robert · 11-01-2012, 12:21 AM

Huh? Why can't you "keep from filling the tank slightly above the bottom of the inner neck"? When I'm filling up, I just watch the gas level rise and when it's a couple inches or so below the rim, I release the nozzle trigger. No problems. Maybe I'm missing something here.

whoaru99 · 11-01-2012, 07:31 AM

Sounds like first step is to check/confirm the tank vent isn't partially pinched/obstructed.

Filling to the bottom or somewhat higher than the bottom of the filler neck is fairly commonplace. While my Vulcan isn't the same model, I usually fill into the neck some. On some occasions way into the neck. I went too far once trying to make for an extended refuel ride and had a little gas leak out of the overflow/vent tube. I think I got about a gallon or so more in than stopping at the bottom of the filler.

markstep · 11-01-2012, 07:41 AM

I agree with whoaru99, that there may be a problem with your vent tube. I fill into the neck all the time without a problem. I do hear my tank vent on occasion, but have never had a problem with leaking yet.

old · 11-01-2012, 09:09 AM

Quote:

Originally Posted by PI Robert

Huh? Why can't you "keep from filling the tank slightly above the bottom of the inner neck"? When I'm filling up, I just watch the gas level rise and when it's a couple inches or so below the rim, I release the nozzle trigger. No problems. Maybe I'm missing something here.

I just want it as full as possible and mis-judge the level with the bike sitting on the side stand. If I'm going to continue riding, I don't worry about it.............in a few miles the level will be drawn down to below the neck. The "leaking" thing has only occured once, and that was in the heat of hot summer.

I was just curious. Will probably continue the way I'm doing it now unless there is a problem in the future.

Thanks for the replies.

P.S. I don't ever hear any noises coming from the vent system, so assume it is working properly.

reddyford · 11-01-2012, 09:39 AM

Quote:

Originally Posted by old

P.S. I don't ever hear any noises coming from the vent system, so assume it is working properly.

But you should hear your gas cap venting, especially on a hot day. It's a whistling sound. It may be clogged, so unclog from the inside (cap open) with a small wire.

old · 11-01-2012, 11:57 AM

Quote:

Originally Posted by reddyford

But you should hear your gas cap venting, especially on a hot day. It's a whistling sound. It may be clogged, so unclog from the inside (cap open) with a small wire.

I'll check it out. Thanks.