Raw Fuel Smell/ Gas Boiling in Tank

bigjoez

I have a couple motor officers complaining and I verified on one that their motor will run like :pie1::pie1::pie1::pie1: when they are running it during the hot parts of the day and the motor is very hot as well. The bike cooling temperature is in operating range with no signs of overheating but they opened their gas cap to look and the gas was gurgling(boiling) inside the tank. Three have also had complaints that when they get home from shift and let their motor sit for a while in their garage they can smell a very strong fuel odor coming from the bike. Anybody have anything happen to them like this?
 
My 1st thought would be to check the vent tubes to make sure they aren't crimped somewhere.
 
I seconed the vent tube check. Also these tanks gurgle. Mine does it to some extent in all types of weather. Just part of the loop system.

Describe the symptoms of how they are running poorly. Perhaps with more info we can isolate the problem.
 
Opening the cap, removing pressure from the tank, when the fuel is warm may cause any dissolved gasses to begin percolating out. It's kinda like opening a beer. Can you hear the boiling before the cap is opened? Is the sealing surface clean and smooth and is the cap gasket in good shape?
 
I removed the gas tanks and inspected all the vent tubes and upon re-installation I made sure I routed the vent tubes so they wouldn't get pinched. I removed the throttle body and replaced the (I call them Manifold) gaskets that hold the throttle body onto the heads and I cleaned out the throttle body with carbclean really well. I removed the vacuum lines and cleaned them out very well too. The officer said he would ride it and let me know if it fixed the problem. His explanation to me is when the bike was really hot from working school zones and the temp outside is well above 110 that the bike seems like it is starving for fuel....like vapor lock he said. I hope this helps and I hope I can report back that the repairs I did might solve the solution.
Smallville said:
I seconed the vent tube check. Also these tanks gurgle. Mine does it to some extent in all types of weather. Just part of the loop system.

Describe the symptoms of how they are running poorly. Perhaps with more info we can isolate the problem.
Click to expand...
 
It's possible the charcoal canister is full of fuel from being overfilled. I've heard the VStrom will run terrible if that cannister has too much fuel and it hasn't evaporated yet.

I can't say I've seen too many say that here but it's a shot in the dark.
 
My fuel was boiling when I was in Moab a couple of years ago. I heard the noise and opened the cap to see it bubbling. I never had any performance problems though?
 
IF it were a carb'ed bike I would have said it was pre-atomisation of the fuel in the carb causing problems...... however I don't know if this can happen with injection bikes with high pressure injection systems...... anyone?
 
It is possible, I won't rule anything out yet. I have a wrecked bike here in the yard so if the officer comes back with the same issue I'm going to swap out charcoal canisters and see if that fixes it. I'm pretty much doing a process of elimination. The officer riding it is kinda of a know-it-all and he talked to the FD and they were telling him fuel has a flash point and if it is boiling then there is a series issue which now becomes my issue.
Mellow said:
It's possible the charcoal canister is full of fuel from being overfilled. I've heard the VStrom will run terrible if that cannister has too much fuel and it hasn't evaporated yet.

I can't say I've seen too many say that here but it's a shot in the dark.
Click to expand...
 
Question, you said the bikes are all 'in the operating range'... But, they should show 3 bars no matter how hot as the radiator / fan / tstat will keep them in that 3-bar area.
 
bigjoez said:
I removed the gas tanks and inspected all the vent tubes and upon re-installation I made sure I routed the vent tubes so they wouldn't get pinched. I removed the throttle body and replaced the (I call them Manifold) gaskets that hold the throttle body onto the heads and I cleaned out the throttle body with carbclean really well. I removed the vacuum lines and cleaned them out very well too. The officer said he would ride it and let me know if it fixed the problem. His explanation to me is when the bike was really hot from working school zones and the temp outside is well above 110 that the bike seems like it is starving for fuel....like vapor lock he said. I hope this helps and I hope I can report back that the repairs I did might solve the solution.
Click to expand...

I don't know for sure that this is the issue but I remember someone saying it is really bad to clean the TBs with carb cleaner. There is a wax type material on the butterflies that looks like it might be carbon deposits but is there by design. Something to make a better seal or prevent them from sticking. I don't recall which.

We don't have those kinds of heat so it doesn't shock me that I haven't seen fuel boil like that. If it is boiling I would imagine that this alone may cause some strong fuel odors from the vent tube.
 
Mine gurgles sometimes... Hard to imagine that it's boiling though... what exactly is the boiling temperature of gas? And if it is boiling, isn't dangerous to open the lid in that condition? Spontaneous combustion? :eek:
:cool:
 
ChipSTer said:
Mine gurgles sometimes... Hard to imagine that it's boiling though... what exactly is the boiling temperature of gas? And if it is boiling, isn't dangerous to open the lid in that condition? Spontaneous combustion? :eek:
:cool:
Click to expand...

Not enough heat for that. Besides the fact that it is boiling doesn't mean it is gas boiling. If they are using Ethanol it could be the alcohol boiling out of the gas.
 
When I opened my tank and looked to see what the noise was, it sure looked like it was boiling.
 
Taken from Chevron MSDS sheet for unleaded petrol.
Attention: the data below are typical values and do not constitute a specification.

Color: Colorless to yellow
Physical State: Liquid
Odor: Petroleum odor
pH: NA
Vapor Pressure: 5 psi - 15 psi (Typical) @ 37.8?C (100?F)
Vapor Density (Air = 1): 3 - 4 (Typical)
Boiling Point: 37.8?C (100?F) - 204.4?C (400?F) (Typical)
Solubility: Insoluble in water; miscible with most organic solvents.
Freezing Point: NA
Melting Point: NA
Specific Gravity: 0.7 g/ml - 0.8 g/ml @ 15.6?C (60.1?F)
Viscosity: <1 SUS @ 37.8?C (100?F)

Given the additives in fuel, I would think the boiling point would be toward the upper limit, after all who would want to sell something that boiled away on a hot day..
 
I thought this was interesting so I Googled gas boiling temp and many places say that gas boils anywhere from
90 to 400 F .

Some places went on to say that the wide boiling range was due to different compounds boiling at different temps.

It appears Sennister hit the nail as the alcohol would have a much lower boiling point .

I did not see any explanation as to why an engine would run poorly but can imagine that since boiling is the process of
a liquid turning into a gas, that may play havoc with the A/F mixture and/or cause fuel pump problems .

While "boiling fuel " doesn't sound safe , if it boils at that low of a temp, it must be a common occurrence .

( There are some Google hits on boiling fuel in vehicles . )

The bikes we are talking about are in Arizona .

The upper gas tank on our bikes gets very hot when the ambient temps are 90F ,
I can only imagine how hot the tank would get if the outside temps are 110 or so .

Maybe keeping a full tank would alleviate the problem ?
 
Something else to try, run a tank of fuel injector cleaner through it (or remove them and clean). Then take the bike out and run the :pie1::pie1::pie1::pie1: out of it. Keep the rpms up and apply a load (like going up hill). Lots of sitting while running and low speed driving can cause build up of carbon on valves and injectors. Take it out and run the rpms up for awhile and see if it helps.
Also I would try and replicate the conditon that he is complaing about just to make sure its not subjective.
 
The more I think about it, the more this sounds like the classic fuel pump issue. Seems like they get weak when they get hot.
Ask him if the problem goes away after he fills the tank.
 
My '04 ST1300 has the gas boiling issue as well. I've posted in another thread my only real performance issue is sluggishness around 28-3000 rpms at steady throttle (decreased acceleration is not noticable, but at steady RPM there is a burble in that range). Of course, we've had a blazing hot summer this year. Whenever I stop after a ride, I will notice a definite strong gas oder and within 10 minutes, I can hear the gas boiling in the tank. Opening the cap reveals the 'rolling' boil. Bike starts as normal in this condition, but it is rather disconcerting to hear your bike gurgling in the garage and having to open the garage door to air the place out!
 
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