Help me please. Do all ST1100's have an evaporative canister? My 1994 standard model runs well, idles well but stinks of gasoline about 10 minutes after I shut it off in the garage. I haven't pulled the carburetors yet as it runs so well and disappears after sitting overnite in the garage. I will pull the carbs if that's what it takes, but I just want to make sure there's no canister somewhere under the Tupperware that could be spewing these fumes. The vacuum fuel valve has already been removed with no change. There are no signs of any leakage to be seen. Thanks for your time and help. Mike in Mansfield TX
Strong gasoline odor for 12 hours after shutoff w/ no leak visible.....
- Thread starter Emjayw
- Start date
its the vacuum fuel shutoff on the right side of the engine, and it can be easily bypassed. Mine failed such that fuel was leaking into the #3 (right rear) cylinder and fouled the plug, and also had the strong gas smell after turning the engine off. When I pulled it apart there was a tear in the vacuum diaphragm.
pull off the saddlebags, seat, side covers, top shelter and you'll see it on the right hand side just rear of the airbox. The small diameter vacuum line can be plugged, and the two fuel lines can be spliced together.
edit for clarification on why the fuel leaks into cylinder 3:
The vacuum line that operates the diaphragm is from cylinder #3 (the same one that you would use to carb sync the #3 cylinder) If the diaphragm leaks, fuel can flow through the opening in the diaphragm, down the vacuum line and into cylinder #3. So after bypassing the shutoff, check your #3 plug to see if its fouled. I think I've read here that there is more than one failure mode, so your plug might be OK, but its worth checking it.
pull off the saddlebags, seat, side covers, top shelter and you'll see it on the right hand side just rear of the airbox. The small diameter vacuum line can be plugged, and the two fuel lines can be spliced together.
edit for clarification on why the fuel leaks into cylinder 3:
The vacuum line that operates the diaphragm is from cylinder #3 (the same one that you would use to carb sync the #3 cylinder) If the diaphragm leaks, fuel can flow through the opening in the diaphragm, down the vacuum line and into cylinder #3. So after bypassing the shutoff, check your #3 plug to see if its fouled. I think I've read here that there is more than one failure mode, so your plug might be OK, but its worth checking it.
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Had the same problem after I bought a low mile garage queen 1991. Tank full...no smell. partial tank with engine hot, same problem you are describing. The vent from the gas cap took a lot of pressure to vent. I replaced the cap and hose with new and the problem went away. It returned a year later. Couldn't find any leaks and there was no pressure in a hot tank so I rebuilt the vacuum shutoff...located on the right side top of the tank by the filter. The diaphragm was intact but really floppy and was not shutting off the gas. Probably leaking into the carbs and evaporating out the overflow tubes. Got a rebuild kit from Dennis Kirk (www.denniskirk.com). No more fuel smells.
Check both the gas cap and vacuum petcock (shut off valve).
Check both the gas cap and vacuum petcock (shut off valve).
I think Oldbikefixr has the right combination there; I know you've taken the vacuum petcock out (so have I) so if there is excess vapour pressure from engine heat soaking into the fuel in the tank, this should escape through the fuel cap vent or if that isn't functioning or allows the pressure to go too high, the next path is to overflow a carb that has a leaking float valve.
My suggestion in the first instance would be to disassemble/clean/replace the cap (and ensure the vent hose is clear), and if that is not successful then look to the carb float valves.
My suggestion in the first instance would be to disassemble/clean/replace the cap (and ensure the vent hose is clear), and if that is not successful then look to the carb float valves.
Tottally agree with Oldbikefixer and TerryS, bettin' the internal vent of cap is restricted
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I know you said you see no leaks whatsoever, but I thought the same thing until I 'really' looked close...my fuel tank sender gasket (on the side of the tank) is giving up the ghost. It is showing itself by getting on the frame, and all the way back on top of the swingarm. Not saying you got the same thing going on, but it's another place to look. The smell of gas got gradually stronger as time went on (obviously).
Frank
Frank
On my ST1300, ( I Know....different animal) , I got a strong gas smell after filling the tank too much, and flooding the carbon canister. I blew out all the lines, but just had to be patient as it cleared. I now fill on the sidestand, so as not to overfill.
Only California bikes have an EVAP canister and then only certain years? If your bike has an EVAP system it will be shown on a diagram under the seat that would show the routing of the vacuum hoses.