2007 ST1300 gas fumes from hose underneath... concerned.

barrycomo · Jun 25, 2016

Ok... I have searched but not found a close situation.

Started last year in Colorado in very high Temps. Gas started running out of vent hose underneath until I opened the gas cap. Rest of trip was uneventful but still lots of gas smell.

Now this trip again in CO and really rich gas fumes from vent hose but smell is more varnish like. I could easily see the fumes pouring out until I popped the gas cap and they dissipated mostly.

So no wet gas coming out but the smell is unnerving. It is easily smelled from 15 feet.

Any ideas or others experience the same?

Thanks in advance!

James

SMSW · Jun 26, 2016

I have dropped my bike immediately after filling up at a gas station (oil, water and slippery concrete) and saw NO leakage of gas from the full tank from the cap. It probably took a couple of minutes to get the bike up (seemed like forever). So the locking cap has to be sealed and virtually air - or liquid tight. My new Oberon cap has a tiny hole in the cap to let air into the tank - and I've smelled gas on a couple of occasions since I swapped the OEM cap for the Oberon.

I'd guess that the high temps and lower air pressure at 5000 feet elevation effectively gives your gasoline a higher vapor pressure (compared to say 70 deg weather at sea level) and it is more prone to evaporation. You might check the connections where the overflow/vent hose joins the tank.

Oldbikefixr · Jun 26, 2016

Not quite the same bike. My 1991 started smelling like raw gas back in the early Spring. There were no drips on the garage floor so I started tracing from the vent hoses back. Found the vent from the gas cap mostly plugged. When the bike was hot, mostly is here, pressure from the warm gas vapor would build up and blow excess gas into the carbs until the pressure was relieved. I replaced the gas cap with a new one and that part of the problem went away.
Look for a blockage somewhere in the vent system. Move on to more expensive or time consuming areas from there.

barrycomo · Jun 26, 2016

SMSW said:
I have dropped my bike immediately after filling up at a gas station (oil, water and slippery concrete) and saw NO leakage of gas from the full tank from the cap. It probably took a couple of minutes to get the bike up (seemed like forever). So the locking cap has to be sealed and virtually air - or liquid tight. My new Oberon cap has a tiny hole in the cap to let air into the tank - and I've smelled gas on a couple of occasions since I swapped the OEM cap for the Oberon.

I'd guess that the high temps and lower air pressure at 5000 feet elevation effectively gives your gasoline a higher vapor pressure (compared to say 70 deg weather at sea level) and it is more prone to evaporation. You might check the connections where the overflow/vent hose joins the tank.

Thx.

I am wondering now if the evap canister got full of gas and now i am smelling that as the fumes escape. No dripping fuel this trip, but dang, the amount of fumes seem excessive... and the smell is pungent like varnish.

Thx again!

BakerBoy · Jun 26, 2016

Barry, if you tip it over or overfill or otherwise get gas somehow drawn into the charcoal canister (however unlikely), what you describe would be the result. At high altitudes, more vapor generation is possible, adding to your awareness of the issue. If the canister is mostly plugged (as in wet with fuel or varnished fuel), opening the gas cap may give you a puff of vapor as the tank pressure is released (pressure existing solely because the canister is partially obstructed).

It sounds like your gas cap is working correctly (it should allow air to enter the tank, but vapors aren't allowed to exit).

What to do? Don't stop riding and you'll never smell it.

barrycomo · Jun 26, 2016

BakerBoy said:
Barry, if you tip it over or overfill or otherwise get gas somehow drawn into the charcoal canister (however unlikely), what you describe would be the result. At high altitudes, more vapor generation is possible, adding to your awareness of the issue. If the canister is mostly plugged (as in wet with fuel or varnished fuel), opening the gas cap may give you a puff of vapor as the tank pressure is released (pressure existing solely because the canister is partially obstructed).

It sounds like your gas cap is working correctly (it should allow air to enter the tank, but vapors aren't allowed to exit).

What to do? Don't stop riding and you'll never smell it.

Ha!

I dont seem to have any excess pressure when i open the cap... but when i did open the cap, there was a noticable reduction in fumes escaping the tube from below (no wet gas anytime). I had theorized the pressure was exiting via the tube as expected until i opend the cap and the pressure dissipated.

Ok... i am headed into the furnace and to the north rim of the grand canyon. Bryce, Zion, Moab, Ouray, then a hot run back to Mo.

barrycomo · Jul 3, 2016

Absolutely no problems this trip with the ST... and the smell must be the canister. I plan on changing it out and feel that will fix the varnish smell.

Thanks for all the support.

James.

2007 ST1300 gas fumes from hose underneath... concerned.

barrycomo

SMSW

Oldbikefixr

barrycomo

BakerBoy

It's all small stuff.

barrycomo

barrycomo