Vapor Lock

[christianguitarest]

Last week I rode to Kansas City to go to a conference. Its a 544 mile ride to Lea-wood (that where the conference was in Kansas City) from where I live. I broke down 2 times going there and once coming back tue to vapor lock. It was 105F on Monday when we rode down there and 98F on the way back. Kansas and Missouri Apparently have Ethanol in all of there gas. What can I do to prevent vapor lock on trips like this and is there a product that you have used and has worked when added to ethanol to keep it from messing your bike up. It was maddening to be in rush hour traffic in Kansas City with the bike constantly trying to die and the only remedy was to run it in prime.

[msgoodwrench86]

We have starting using "Startron" for when we cant get non-ethanol fuel. Not all gas stations carry ethanol fuels tho. I work at Martin Oil (exit 225 on I-70 in kansas) our fuel is non-ethanol. My boss brings in his own fuel and he doesn't like the ethanol.

[hardlydangerous]

FYI most small non brand name fuel stations PREMIUM fuels and almost all Marinas are non ethanol. (regardless what the pump says)
Non Ethanl fuels are actually cheaper so the mom and pop fuel stations actually have better fuels and pay less for them. The down side is they often charge the same or more due to the lack of sales/volume etc.

Ive been preaching for years about the use of 87 octane and the how there is no need to run anything higher. Well I have proven myself wrong kinda.... true the engine runs fine with 87 and no knocking or ping and there is no need to run anything higher. However the 87 /89 octane fuels are loaded with ethanol. I started testing every single tank last year... NOW I wont run anything but SHELL Vpower . Using my Fuel friend app on my android, I get 5-6 mpg better mileage average with mixed riding and even better on hwy. Thats HUGE. For my test I rode a single brand for 60 days Esso, Sunoco/ultramar, Petrocan and Shell. 30 days running reg 30 running premuim.
Hands down the best performance and mileage is with the Shell Vpower non ehtanol fuel.
FWIW in Muskoka and many marinas non ethanol 87 is available as well
Petrocan and sunoco were by far the worst, but none were close to the shell

besides the fuel app testing just the amount of carbs ive had to clean and rebuild this past couple years is mindblowing and reason enough for me to stop using ethanol fuels. Grey line falling apart and causing bikes to clog up overnight. Several bikes just in the past few weeks Ive had to swap out fuel lines from the old style gray line to new quality blackline. I had one set of carbs from a 2009 GS500F that looked like baked on yogurt inside the bowls and smells like azz.

I say screw it Shell Vpower for me from now on.

[Mikefox01]

Ethanol is bad news for non pressurized fuel systems, gravity fed being one of them.

[Kreylyn]

with the bike constantly trying to die and the only remedy was to run it in prime.

FYI... this isn't anything to do with the fuel type you used. While I personally have had issues with ethanol additives and am not fond of them for my bike application and purpose, the "resolution" you stated isn't related.

Either you have a petcock issue, you have a ventilation issue with your gas tank, or you have a fuel flow issue with a fuel filter slowing flow/kinked fuel line slowing fuel flow.

Krey

[christianguitarest]

I checked the petcock and it is fine as well as my vents are working just as they should. I also pulled my fuel filter and it was clean. I spoke with a tech. and his thought was I only had issues when I got to half a tank both times, it was 105F, and the fuel was boiling. He said it was simply to hot for the vapor to escape quick enough. I have been riding this week at home and have had no problems nor did I have any problems riding in Kansas City the whole week we were there, just the long rides there and back in +100F weather.

Something else I noticed that was funny was the fuel was blue in Missouri. Is that a common practice in other States? For us here in South Dakota ethanol fuel is the cheapest but the refineries are right here as well, in fact i live within 30 miles of 2 of them. Still, I never run it.

Thanks for the additive advice and the app, Ill have to check it out.

[Kreylyn]

as well as my vents are working just as they should.

Vents... Plural?

Don't think we are talking about the same thing.

Fuel "boiling" in your tank won't cause the issue you described. This would increase the pressure and force fuel out faster.

Fuel "boiling" in your carbs would cause the issue if the flow into the carbs was restricted to prevent refilling them and lowering the fuel level. If your petcock and filter are "fine"... then it's back to the tank vent.

Krey

[Kreylyn]

Another possibility for this issue...

http://katriders.com/vb/showthread.php?p=2220605

Is your bike a CA model?

Krey

[christianguitarest]

Thanks for the thread, but no I do not have the cali model, and fuel (vapors) is able to ven out of the vent hose that runs next to my oil overflow line and vents just fine. The second vent I was talking about is the hole that is under you gas cap. If you lift your cap on the right side closest to the handle bars there is a vent hole into the tank.

A petcock does not work off of pressure but vacum. More pressure in you tank does not make the fule come out faster, thats just crazy talk! If pressure builds to high in the tank fuel cannot get though your petcock. This is also why you can take your tank off you bike full of fule if its in run, there is no vacum to pull the fule out, but if you were to create a vacum on the petcock fule would come out. If it was about pressure in the tank, then fule would run out of the petcock when you take your tank off. Petcocks are vacum operated, not pressure operated.

Thanks again for the reply, I did check just in case and no I do not have an cali evac system, although that would have been a nice fix. Sounds like that guy had a lot of trouble, I only had it after hours of riding in the sun at interstate speed and only when my tank got to half full or less. Ill just stay away from ethanol and gas stations that have no markings.

[Kreylyn]

Thanks for the thread, but no I do not have the cali model, and fuel (vapors) is able to ven out of the vent hose that runs next to my oil overflow line and vents just fine. The second vent I was talking about is the hole that is under you gas cap. If you lift your cap on the right side closest to the handle bars there is a vent hole into the tank.

A petcock does not work off of pressure but vacum. More pressure in you tank does not make the fule come out faster, thats just crazy talk! If pressure builds to high in the tank fuel cannot get though your petcock. This is also why you can take your tank off you bike full of fule if its in run, there is no vacum to pull the fule out, but if you were to create a vacum on the petcock fule would come out. If it was about pressure in the tank, then fule would run out of the petcock when you take your tank off. Petcocks are vacum operated, not pressure operated.

Thanks again for the reply, I did check just in case and no I do not have an cali evac system, although that would have been a nice fix. Sounds like that guy had a lot of trouble, I only had it after hours of riding in the sun at interstate speed and only when my tank got to half full or less. Ill just stay away from ethanol and gas stations that have no markings.

You don't think I understand how the petcock works... that's cute.

Okay, you seem to be not understanding a few things I've mentioned, and confused by the pressure comment, so I'll elaborate.

1st... there is only 1 "tank vent". That is the pressure equalization vent in the gas cap. This makes sure pressure does not build up or worse, create a pressure void situation that prevent fuel from flowing out as the level decreases. The CA model uses a "fume capture" component inside the tank as mentioned in the prior link. This is NOT a vent. It's not supposed to be open unless the engine is running to pull fumes. The build of pressure from fumes due to direct sun exposure is what was causing the issue in that link. The pressure was over riding the function that stops fuel from flowing into the capture system. Thus the "unexpected problem" he had and described.

2nd... Of course the petcock IS vacuum operated. I never said otherwise. How the petcock normally works has NOTHING to do with pressures in the tank. Yes, I fully understand how the petcock works. I wasn't combining 2 things into one as you suggested. What you didn't understand is that when the engine is running, the vacuum applied to the petcock will open the plunger that stops fuel flow, allowing it to flow. The speed of this flow is partially dependent upon the pressure of the fuel above it in the tank. Normally this should be just "gravity fed" from the weight of the fuel above it. If the tank vent is stopped up and additional pressure has built up due to fumes, this pressure is much higher than normal operation. This can force fuel past the float needles. This can even force fuel past the petcock if the pressure is significant enough. If the pressure is lower than normal due to a pressure void, the flow will slow down or even stop. This is why people mentioned to "open the gas cap and listen for a hiss" sound when people have fuel flow issues. So yes, the ambient pressure inside the tank DOES affect the fuel flow.

3rd The "vent" you mentioned that runs out next to your "oil overflow line".... : WTF dude. You don't have either of those as you have labeled them. There isn't a "line" on the fuel tank that vents pressures inside it. A katana has a tank "overflow" or "drain" line. This isn't even exposed to the inside of the tank and internal pressures or lack of would have no effect... unless you have a hole in the drain line that runs through the gas tank. It starts at the top outside next to the fill cap. If you get water there from rain or over fill the tank, then the fluids will drain through that hole, all the way through the tank, and out the bottom. Generally there is a drain line connected on the bottom of the tank that routes that away from the engine and under the bike. If that was opened to your fuel inside, you would constantly have water issues and fuel pouring out it when you fill up. NOT a vent.

I really want to know what this "oil overfill line" is... are you talking about the crank case vent? The drain line for the airbox?

I'll mention there are 2 vent lines on the carbs, or should be. This allows for the air to escape as the bowls fill with fuel. Just thought I would mention them since we are discussion the "lines" as routed on the bike. There may also be a drain line attatched to the fuel level sensor so that if that springs a leak, fuel will be routed away from the engine.

Finally... per your description...

I only had it after hours of riding in the sun at interstate speed and only when my tank got to half full or less.

This is a classic symptom as described above... the pressure inside the tank is slow to equalize or actually lower than the ambient air pressure, and thus fuel is not flowing out or flowing slower than normal. This is generally caused by a partially stopped up tank vent (the gas cap one), a fuel line has kinked partially to slow fuel flow, an inline fuel filter has partially stopped up or is trapping air in it reducing fuel flow, or the carb vent line(s) have a partial stoppage that isn't allowing for the fuel to flow into the carbs fast enough due to pressure equalization.

If you think it's only heat related, then the 2 primary points I would look at is the fuel lines and carb vent lines, but I'm not ruling out the vent in the gas cap.

With the fuel lines, if overly hot, they become much more pliable and will bend much easier. If they are routed in a way that has them turning a tight turn they may keep a gradual radius when cool. When it gets hot though, they may soften up wich can cause them to temporarily "kink" and slow down fuel flow.

If the carbs get overly hot, then I could see where that could cause a situation where either the vent lines on the carbs are not allowing fuel to flow in fast enough as due to not equalizing the pressure quickly enough. That build up could even keep the float needles closed due to pressure building up and preventing them from dropping down, also stopping fuel from filling the bowls.

The fact the problem only happens when the tank is "half fuel or less" tells me the "fuel pressure" being forced out of the tank isn't enough due to the lower volume. If you fill it and it sovles the problem, then the added weight of the extra fuel is providing enough weight to increase the fuel pressure of the gravity fed system to over ride the issue.

Krey

[thetable]

Fuel "boiling" in your carbs would cause the issue if the flow into the carbs was restricted to prevent refilling them and lowering the fuel level.

When the fuel in the bowls on my Kat would start to boil, it was easy to tell, because the idle would start to climb.

I think Kreylen is on the right track.

[christianguitarest]

Ok, sorry i miss understood what you ment. The oil line I was referring to is the line coming from the air box. When the fuel was boiling in the take the drain line had tons of fumes coming out of it. I did just buy the bike in March so I think there may need to be some TLC this winter. Ill check the carb lines, that seems to be the most reasionable as when the bike shut down there was no sputtering or anything, I would just go from full power to the bike being dead, just like if you ran out of fuel. The bike would just lose power and be done, no restarting for a few minutes.

Thanks for the great info, havent had any issues sense while riding in the hot 120 miles round trip, but I also dont want to have these issus again because it really sucks to be 4 hours from home and on the side of the road!