How does heat affect my fuel feed?

[petekadish]

Yesterday, I road across the Nevada Desert on HWY 50 on my Venture. As I neared the Utah boarder, temps rose to almost 110 degrees. While I showed that I still had fuel in the tank and I had not yet switched to reserve, I began to feel those momentary surges and sputters which typically occur right before running out of gas. So, I backed-off on my speed and somewhat "drafted" behind a truck for the last 25 miles before I reached a gas station.

 

After filling-up and getting back on the highway, I again began to feel similar surges and sputters occasionally as I attempted to reach speed. This time however, I knew full well that I had plenty of fuel, so that couldn't be it. Then, I began to think that perhaps the in-line fuel filter I installed some time ago might need to be changed. After a little while the temperature dropped down to the upper 90s and my fuel feed issue seemed to disappear over the last 100 miles.

 

So, was it probably a heat-related issue in the carburetors or more likely the fuel filter? If it was the heat which was affecting the performance, what's the best way to deal with it when stuck in the heat? And, if it is the heat which is causing the problem, what exactly is happening?

 

Anyway, we arrived safe and sound, albeit a little bit on the crispy side.

 

Thanks guys and Be Safe!

Pete & Sandy

[bryan52577]

?? Could the "vent" on the cap be sticking?

 

Bryan

[wes0778]

Vapor Lock???

[MikeWa]

I just made that trip in May and had a similar experience. There is quite a variance in altitude along that route. For me the symptoms you described were altitude related. It wasn't really a problem just the way the engine ran at altitude. Lugged very easily on the slightest incline. May not be your problem but I wouldn't just rule it out either.

Mike

[bryan52577]

You said it was 110*, and with the heat from the engine (while seldom occurring) can cause the fuel to "boil" in the fuel lines and cause it to feel like it is running out of fuel. (Vapor-lock) "See below"

Some of the HD riders around here put an extra hose or some insulated tape around their fuel lines so the engine temp will not cause the fuel to "boil" in the lines and shut them down.

 

Chemical and Physical Characteristics of Ethanol and Hydrocarbon Fuels

IG

2 - 5

Characteristics of Gasoline (A Hydrocarbon)

Hydrocarbon fuels (gasoline, diesel fuel, kerosene, jet fuel, etc.) generally have similar

characteristics whether they are flammable liquids or combustible liquids.

 

Gasoline is a hydrocarbon produced from crude oil by fractional distillation. It is non-water miscible (which makes it hydrophobic) and has a flash point of approximately -45°F, varying with octane rating. Gasoline has a vapor density between 3 and 4. Therefore, as with all products with a vapor density greater than 1.0, gasoline vapors will seek low levels or remain close to

ground level. Gasoline has a specific gravity of 0.72–0.76 which indicates it will float on top of water since it is non-water miscible or insoluble. Its auto-ignition temperature is between 536°F and 853°F, and it has a boiling point between 100°F and 400°F depending on fuel composition.

Gasoline is not considered a poison but does have harmful effects after long-term and high-level exposure that can lead to respiratory failure. Smoke from burning gasoline is black and has toxic components. Gasoline’s greatest hazard is its flammability even though it has a fairly narrow flammability range (LEL is 1.4 percent and UEL is 7.6 percent).

 

Characteristics of Ethanol (A Polar Solvent)

Emergency responders are generally not going to encounter pure ethanol unless they respond to an event at an ethanol production facility. Ethanol for use in motor fuel blends will generally be denatured with up to 5 percent gasoline or a similar hydrocarbon (E-95) for any style of transport. Nevertheless, the following discussion of the characteristics of ethanol will be based on pure rather than denatured product, for in actuality the denaturant will have minimal effects on product characteristics.

Chemical and Physical Characteristics of Ethanol and Hydrocarbon Fuels

 

 

Pure Ethanol is a polar solvent that is water-soluble and has a 55°F flash point. Ethanol has a vapor density of 1.59, which indicates that it is heavier than air. Consequently, ethanol vapors do not rise, similar to vapors from gasoline, which seek lower altitudes. Ethanol’s specific gravity is 0.79, which indicates it is lighter than water but since it is water-soluble (it be considered hydrophilic). it will thoroughly mix with water.

Ethanol has an auto-ignition temperature of 793°F and a boiling point of 173°F. Ethanol is less toxic than gasoline or methanol. Carcinogenic compounds are not present in pure ethanol. Like gasoline, ethanol’s greatest hazard as a motor fuel component is its flammability. It has a wider flammable range than gasoline (LEL is 3.3 percent and UEL is 19 percent).

In a pure form, ethanol does not produce visible smoke and has a hard-to-see blue flame. In a denatured form there is little to no smoke, but a slight orange flame may be visible.

Interestingly, ethanol and some ethanol blends can conduct electricity while gasoline does not and is considered an electrical insulator.

 

The most striking difference between these two fuels is that unlike gasoline, ethanol mixes easily with water. While it is possible to dilute ethanol to a condition where it no longer supports combustion, this is not practical in the field as it requires copious amounts of water. Even at 5 parts water to 1 part ethanol, it will still burn.

 

 

Bryan

[sKiZo]

Already been covered, but worth repeating.

 

The low pressure fuel line is probably what's causing the problem. Depending on the line routing, if it's laying right on the motor, the fuel can boil and cause vapor lock. Only real cure is to let it cool. If it's just an occasional thing, no biggie, but next time you're in there, check the fuel line from the petcock and figure out a way to prop it away from the hot stuff. O-rings around the line or just some spacers cut out of rubber hose should do the trick. You don't want to run a solid chunk of line over the fuel line - that will eventually hold even more heat. Routing isn't especially critical for fuel delivery on a pumped system, so I might even change out to a longer hose and try running it outside the frame rail if it were a regular issue. I've also heard that an extra inline fuel filter can help by allowing any vapor to filter out of the line there instead of blocking the line. I know on some bikes you can remove the vent plug completely, but then you risk a fuel spill on a tipover. Never tried it with a yamafour ...

 

Also, do try removing the tank cap next time it acts up. If you hear a whoosh or burp, the tank isn't venting right. Especially common on the CAL tanks. Some of the caps are rebuildable, some aren't depending on the model, but you can usually blow out any obstructions and free up the vent with high pressure air. Couldn't hurt.

[petekadish]

Okay guys, thanks! I'm pretty convinced that it was a vapor-lock related issue. At least it seemed temporary during the peak heat of that riding day and disappeared as it cooled down a bit. Plus, the bike never experiences any issues when it comes to altitude so I know that wasn't it.

 

As usual ..., very helpful replies!

 

Be Safe!

Pete.

[bryan52577]

Okay guys, thanks! I'm pretty convinced that it was a vapor-lock related issue. At least it seemed temporary during the peak heat of that riding day and disappeared as it cooled down a bit. Plus, the bike never experiences any issues when it comes to altitude so I know that wasn't it.

 

As usual ..., very helpful replies!

 

Be Safe!

Pete.

 

?? Don't rule out altitude to fast, I bet it may have played a part too.

Approximate boiling point of water (a decrease of about 1 degree for every 540 feet of altitude):

 

Altitude

Temperature

 

 

Sea Level 212° F.

2,000 Feet 208° F.

5,000 Feet 203° F.

7,500 Feet 198° F.

10,000 Feet194° F.

Bryan:confused24:

[petekadish]

I live in Orem, Utah at 4,770 feet above sea level, and the bike runs perfectly normal. I ride it up to Park City at 8,000 feet, and it runs fine. When riding down in the Bay Area in California earlier this week, I didn't notice any issues on the way there (same as my return route), or while there. So, that's why I don't think that it's an elevation issue. I could be wrong though, it happens pretty often - ask my wife.

 

Thanks!

Pete.

[MikeWa]

Air is less dense as altitude increases. It has to do with the atmosphere on our planet not Yamaha. Naturaly asperated engines (no turbo, no supercharger, no built in oxygen supply) loose about 3% of their power per 1000 feet. Depending on how you ride your bike you may or may not notice it but it does occur. If you normaly ride at 5000 feet that will seem normal to you. And a power increase at lower altitudes will just require a little less throttle. Probably not noticeable. Since I live and ride near sea level I notice a 15 plus percent loss in power very quickly. All engines experience this, Venture or otherwise. It doesn't matter how much you love or don't love your bike it happens any way.

Mike