Gas Smell

[Grumpy]

All:
My apologies if this has been covered before, I did a search and did not find any specific information.
After a ride of about 45 minutes or so yesterday at highway speeds, when we pulled into the garage, there was a strong gas fume odor. Using my old mark 1 smeller (ancient nose) the smell seemed to be coming up from around the top triple tree. I could not detect the odor from around the fuel cap, though when I raised the cap, it seemed as though it might have had a slight vacuum. That might just be my over-active imagination, though.
This seems to happen when the bike sits in the hot sun for a while as well.
I intend to do a start valve sync as soon as the snow flies and the riding is curtailed for a few days, so that would seem to be the best time to trace this down and solve the problem. Has anyone out there seen the same thing? Are there any obvious places to start tracing the problem?
Thanks in advance...I know there are some very knowledgable folks on this forum that can point me in the right direction!

 

[NobodySpecial]

Pull the seat and VISUALLY check the fuel elbow hose very carefully. It can and will rot, crack, and potentially make a disastrous leak. DO NOT lift the tank to replace it until the fuel is at one bar on the gauge.

 

[SMSW]

Your bike is 15 years old rubber parts could be failing. There is also a vent hose on the gas tank - these are accessible at the back of the tank on the bottom. You cannot thoroughly examine these hoses without removing the tank, so run the gas down to one bar and be careful removing the spring clamps. Honda's gas tank hose clamps come new compressed (in the expanded position) with a metal clip holding them open. Does your bike have a charcoal canister? Check those hoses too.

You might consider examining all of the rubber hoses on the bike this winter.

 

[SupraSabre]

Your bike is 15 years old rubber parts could be failing. There is also a vent hose on the gas tank - these are accessible at the back of the tank on the bottom. You cannot thoroughly examine these hoses without removing the tank, so run the gas down to one bar and be careful removing the spring clamps. Honda's gas tank hose clamps come new compressed (in the expanded position) with a metal clip holding them open. Does your bike have a charcoal canister? Check those hoses too.

You might consider examining all of the rubber hoses on the bike this winter.

Along that line, if you have never replaced the hose between the upper and lower gas tank, Now would be a great time to do that!

 

[Grumpy]

Thanks Guys. All great suggestions and less complicated than I had feared. Once I have a few days break when the weather is too bad to ride (snow and ice on the roads) I intend to do the start valve sync, rebuild the forks and added to that will be checking, replacing hoses and fittings as needed.
Spousal unit is not too keen on buying a Goldwing, so I need to invest in the ST for the long haul. (or maybe get the GW and keep the ST)

 

[Igofar]

Remove the lower right black cowling and inspect/un-clog the vent lines. Spiders, bugs, and mud clog these things up, as well as all the dirt you find around the over flow port near the gas cap that drops down into the tube.
Blow some compressed air down the vent and I'll bet you blow out all kinds of crap.
Also pull the very bottom line from the canister and clean it out, its often found clogged up.

 

[CYYJ]

There are four hoses under the upper fuel tank that you should investigate. The picture below, taken with the upper fuel tank removed, shows all four.

Fuel System Hoses (underside of upper fuel tank)


The really big hose (about 25% of the way up from the bottom of the picture) is the hose that transfers fuel from the upper fuel tank to the lower fuel tank. Carefully inspect the condition of that hose - it is a really safety-critical part - but I don't think that is the cause of your problem. In your post above, you wrote:

when I raised the cap, it seemed as though it might have had a slight vacuum.

If there was any leakage or breakage in that big fuel transfer hose, you would not have a vacuum or a pressure in your fuel tank, because the vacuum or pressure would relieve itself through the opening in the fuel transfer hose.

The other three hoses (smaller ones at the top of the picture) function as follows:

One is a drain line from the little overflow hole (scupper hole) that you can see at the 9 o'clock position when the fuel filler cap is raised up. If you accidentally overfill the fuel tank, the excess fuel that spills over the top of the fuel filler opening into the ring around it runs down that scupper hole, through a metal tube in the upper fuel tank, and out a drain hole on the underside of the upper fuel tank. The hose that connects to that opening (the one labelled 'drain' in the photo of my fuel tank, below) terminates at the very bottom of the motorcycle, under the engine, where overflow fuel gets dumped on the ground.

Hose Connection Points under Upper Fuel Tank


That hose is not the cause of your problem. But, you should check to ensure that it is not blocked by pouring a small amount of water into the ring around the fuel filler opening and observing that the water runs out onto the ground underneath the motorcycle. If that hose (or the metal tube between the scupper hole and the fitting on the bottom of the tank) is blocked, you will have problems with water getting into your fuel tank when you open the fuel filler cap after washing the motorcycle, or after the motorcycle has been sitting outside in the rain. I discovered a "blockage" in my drain hose - the hose kinked when the upper fuel tank was lowered down - and I had to do some creative re-routing of the drain hose to stop it from kinking.

The next hose is the 'breather' hose that connects to the charcoal canister that is directly in front of your right foot when you are riding the motorcycle. Larry (@Igofar ) posted a picture of that canister in post #6 above. Most probably, either that hose is blocked, or there is a blockage further down the line in that breather / charcoal canister assembly. See Larry's remarks above.

The third hose is a vent hose that connects the upper and lower tanks. It's unlikely that hose is your problem.

The most common location that hoses get blocked is down at the bottom of the motorcycle, where hoses vent to atmosphere. They get plugged with mud, or by insects, or they get kinked down at the bottom.

Michael

 

[CYYJ]

Just a postscript - if you elect to replace the big fuel transfer hose, you will need to use a special hose clamp tool to remove (and later replace) the spring-steel clamps at each end of that L-shaped hose. It's suicide to try and remove or replace those clamps using a pair of pliers or Vice-Grips. You can purchase the special tool from any automotive shop, it costs about $15.

Also, as @NobodySpecial advised above, run your fuel down to only one bar on the gauge (the flashing bar) before you attempt to replace that hose. That will ensure that there is no fuel present in the upper fuel tank.

Michael

Hose Clamp Tool

 

[Tom P]

Just a obvious suggestion...check the fuel cap when you smell gas. Pull over and see if there is any wet gas around the fill hole. Mine was leaking out past the cap gasket
Not a lot or all the time, but enough to cause the smell. 178,000 on my bike. Honda does not sell gasket separately. Cap cost around 160.00. Bought aftermarket one off Ebay...17.00 free ship. Looks good and will install soon.

 

[dduelin]

Just a postscript - if you elect to replace the big fuel transfer hose, you will need to use a special hose clamp tool to remove (and later replace) the spring-steel clamps at each end of that L-shaped hose. It's suicide to try and remove or replace those clamps using a pair of pliers or Vice-Grips. You can purchase the special tool from any automotive shop, it costs about $15.

Also, as @NobodySpecial advised above, run your fuel down to only one bar on the gauge (the flashing bar) before you attempt to replace that hose. That will ensure that there is no fuel present in the upper fuel tank.

Michael

Hose Clamp Tool

I don't know about suicide. I replaced mine a couple times and helped a couple others remove and replace the joint hose with just a pair of slip jaw Channellock pliers. This tool's jaws has flat surfaces wide enough to catch on all three tabs.

 

[dduelin]

There are four hoses under the upper fuel tank that you should investigate. The picture below, taken with the upper fuel tank removed, shows all four.

Fuel System Hoses (underside of upper fuel tank)


The really big hose (about 25% of the way up from the bottom of the picture) is the hose that transfers fuel from the upper fuel tank to the lower fuel tank. Carefully inspect the condition of that hose - it is a really safety-critical part - but I don't think that is the cause of your problem. In your post above, you wrote:

If there was any leakage or breakage in that big fuel transfer hose, you would not have a vacuum or a pressure in your fuel tank, because the vacuum or pressure would relieve itself through the opening in the fuel transfer hose.

The other three hoses (smaller ones at the top of the picture) function as follows:

One is a drain line from the little overflow hole (scupper hole) that you can see at the 9 o'clock position when the fuel filler cap is raised up. If you accidentally overfill the fuel tank, the excess fuel that spills over the top of the fuel filler opening into the ring around it runs down that scupper hole, through a metal tube in the upper fuel tank, and out a drain hole on the underside of the upper fuel tank. The hose that connects to that opening (the one labelled 'drain' in the photo of my fuel tank, below) terminates at the very bottom of the motorcycle, under the engine, where overflow fuel gets dumped on the ground.

Hose Connection Points under Upper Fuel Tank


That hose is not the cause of your problem. But, you should check to ensure that it is not blocked by pouring a small amount of water into the ring around the fuel filler opening and observing that the water runs out onto the ground underneath the motorcycle. If that hose (or the metal tube between the scupper hole and the fitting on the bottom of the tank) is blocked, you will have problems with water getting into your fuel tank when you open the fuel filler cap after washing the motorcycle, or after the motorcycle has been sitting outside in the rain. I discovered a "blockage" in my drain hose - the hose kinked when the upper fuel tank was lowered down - and I had to do some creative re-routing of the drain hose to stop it from kinking.

The next hose is the 'breather' hose that connects to the charcoal canister that is directly in front of your right foot when you are riding the motorcycle. Larry (@Igofar ) posted a picture of that canister in post #6 above. Most probably, either that hose is blocked, or there is a blockage further down the line in that breather / charcoal canister assembly. See Larry's remarks above.

The third hose is a vent hose that connects the upper and lower tanks. It's unlikely that hose is your problem.

The most common location that hoses get blocked is down at the bottom of the motorcycle, where hoses vent to atmosphere. They get plugged with mud, or by insects, or they get kinked down at the bottom.

Michael

Great pictures.

 

[CYYJ]

...I found that my tank cap drain hole was blocked.

Hi John:

Mine was not draining either, which is what caused me to do all the disassembly you see in the photos I posted above. I eventually discovered that my problem was not caused by a physical object in the drain hose, it was caused by the drain hose kinking when the upper fuel tank was lowered to the normal closed position.

It was a frustrating problem to troubleshoot, because with the upper fuel tank lifted and propped up in the service position, there was no blockage in the pipe from the fuel cap scupper hole to the drain teat on the bottom of the upper fuel tank, and no blockage in the rubber hose that fits on the drain teat and leads down to the underside of the motorcycle. So I put everything back together... and once again found out that the drain was blocked.

After a whole lot of poking around, I eventually found where the rubber hose was kinking when the upper fuel tank was lowered. Further investigation revealed that the three small rubber hoses (shown in post #7 above) on my motorcycle are not routed correctly, which is what was probably causing the hose to kink. There are two different routing paths for these three hoses, depending on whether the motorcycle is pre- or post- 2007.

I found that I need to order a small part - sort of a retaining clamp - that fits onto the underside of the upper fuel tank measurement fitting before I can correct the hose routing. That clamp has since arrived, and the next time I have to raise the upper fuel tank, I will correct the hose routing and make a detailed post about it.

In the meantime, below is an image from the Honda Service Manual that shows the correct routing for the three small hoses both pre- and post-2007. The red arrow calls out the part that is missing on my motorcycle (you can see in the photos above that this part is missing).

Michael

Fuel Drain Hose Routing

 

[Catmandu2]

This recent return to winter allows me time to to install the tank joint hose,,, that has been in my parts bin for a couple of years. I don't know if the PO's of my bike had ever changed it,, and the only way to get some peace of mind,, is often to get it done yourself. Due to having the heli-bar gen3 handlebar risers,, I elected to remove the tank, instead of propping it up. That made it easier to r&r the air cleaner as well. The old joint hose and oem clamps came off easily. The old hose was harder than the more supple new hose, but showed no cracking. The new oem clamps were no big deal, and were easy enough to adjust with a pair of pliers to get that perfect position. I think regular hose clamps would do a better job,, and suspect that Honda just wants to control the installation parameters,, owing to the critical function. Arguably, the oem clamps might keep better tension over many heat cycles, compared to standard hose clamps. I had run the tank down to 2 bars, plus an additional 20 minutes of riding,,, before starting this process. And that was adequate to drain the upper tank. Not really finished yet,,, as will add gas tomorrow and do a leak inspection. Cheers,, CAt'

 

[rob1313]

Just want to give huge thanks to everyone who posted in this thread. I’ve got a fuel leak on my 06 ST that only happens when the tank is full or close to full. This thread gave me a lot of spots to investigate. Off to the garage I go!