View Full Version : Fuel is it safe

Aunty Jack
29-11-2009, 06:46 PM
Just wondering is it safe to store 2stroke fuel in your boat, while not in use .
The boat does have a cover but im not sure weather its safe or not.
P.S. half a tank with or without breather open or closed.

29-11-2009, 07:05 PM
I always leave mine in the boat with breather open just a fraction,been doing it for years without a problem.



29-11-2009, 07:06 PM

29-11-2009, 07:19 PM
If you have kids old enough to crawl in to your boat, but not old enough to leave it alone when you tell them to , no its not safe. Otherwise you should be fine.

29-11-2009, 10:06 PM
Fuel stored with 2 stroke oil in it goes off faster than normal fuel.

It goes off even faster if it is not stored in a cool position

It breaks down even faster if it isn't in a sealed container

Breaks down faster again if it gets moisture in the tank.

Put it in the garage if you can with breater closed a that is best for the fuel and motor ( apart from fresh) and bit of shake before putting back in boat in case any of oil has settled..

If you are worries about explosion - well a boats bilge ( air fuel mix is heavier than air and dinks) can fill up with vapour so I wouldn't be pulling off the covers with a lit ciggy and wouldn't touch the electrics till you know there is no vapour and it is aired a bit.

That and static electricity is why petrol stations want you to remove tote tanks to fill at the servo on the ground so they are earthed and have airflow around them.

Beter not to leave anything in a boat as thieve have less to vandalise but depends how boat is stored and security. Yeah that is in that imaginary world where we all have loads of space and locked tripple garages.

If you can smell fuel when you are removing the tarp you have a issue

29-11-2009, 10:26 PM
swamp, there would be 1000's of boats around oz all with fuel tanks just like yours, like cormorant said close your breather and if you don't use your boat to often add fuel stabilizer to the tank to keep the gas fresh.

30-11-2009, 11:55 AM
Have just duplicated this from a page on a mower site

Interesting summary on fuel and storage


The petrol used today is different in characteristics and components used as compared to the petrol seen even 5-7 years ago and vastly different than that seen 10-15 years ago.

Two factors are present to shorten the shelf life of fuel:

Economic: stretching the amount of petrol available from a barrel of crude oil
Environmental: addition of oxygenating ingredients in an attempt to improve overall air quality.
Both of the above factors result in fuel which has shorter shelf life, is harder on soft components (elastomers) and leaves deposits (gum, tar, varnish) at a far more rapid rate than for fuels of the past.
In the 1950s, approximately 28% of a barrel of crude oil was refined into petrol. This was known as straight-run petrol. As the most lucrative high-volume product of crude oil is petrol, petroleum companies have developed ever-more exotic refining and cracking methods to pull more petrol from a barrel of crude oil. Today, that 28% has been increased to over 45% and, depending on the source of the crude, can go to as much as 75%. The negative effect in the more exotic refining processes is that they create olefins and diolefins which shorten shelf life due to oxidation and promote the rapid development of tars, gums and varnishes. For this reason, most OPE manufacturers recommend 30 days as the recommended shelf life for petrol. If used in extreme high temperature conditions and stored in an aboveground fuel container (plastic petrol container), we would shorten that to 1 week maximum.

Note: shelf life of petrol can be extended by use of an oxidation reduction compound known as fuel stabiliser. Several manufacturers offer this compound; among the most commonly used world-wide is Sta-Bil (tm) . Use of these compounds as directed can extend the shelf life of petrol as long as 1 year.

It is our position that use of a fuel stabiliser for engines that will be stored for a period of time is superior to draining fuel and running the carburettor dry. The potential for damage to diaphragms and gaskets is far greater as those components dry out.

Oxygenated Fuel

Environmental concerns and subsequent regulations for improved air quality have lead to the use of oxygenated fuels; fuels containing and oxygen-bearing component. Though not present, 12 Property Care Industry adding an oxygenate will provide a lean mixture; improving overall emissions. These compounds also improve octane; something drastically reduced when lead was removed. At the same time, this is also a method to extend the quantity of petrol available from a barrel of crude oil. To the petroleum companies, this has become a very popular practice. The regulations, economics, concern for diminishing supplies and need to keep octane levels high have made use of oxygenates very attractive.

The three most common oxygenating ingredients are: methanol, ethanol and MTBE; a derivative of methanol.
Methanol is produced from natural gas or petroleum and is commonly known as wood alcohol.

Ethanol is produced from corn or grain and is known as grain alcohol and is commonly found in spirits, beer, wine etc. As it comes from a renewable resource, it is looked upon in high regard by environmental groups and the agriculture industry in countries with air quality problems.
All of these components are not without undesirable characteristics. Alcohols (methanol and ethanol) are chemically unstable in petrol. Specifically, they do not want to stay mixed due to the hygroscopic effect when water is present. Alcohol is naturally attracted to and readily absorbs water; to the extent that it will combine with water and, then as the heavier component, it sinks to the bottom of the tank. This process is called phase separation and is a serious concern when alcohol levels are high. As the alcohol/water combination is a the bottom of the tank, it goes inside the engine first and sometimes at a level that poses the potential for engine seizure. The alcohol also acts as a degreasing agent and washes the protective lubrication film off of components; leading to rust, corrosion and the potential accelerated wear. In addition, when used in high ratios, they can cause deterioration of gaskets, grommets, fuel lines, etc.

MTBE (methyl tertiary butyl ether) has eliminated the undesirable effects of straight-run alcohols but has brought in several of its own negative characteristics. The sensitivity to detect MTBE is far greater than gasoline; perhaps by a factor of 10. Simple refuelling in the US has lead to thousands of complaints of headaches, dizziness, nausea, burning eyes and sore throats. Even more of a concern is ground water contamination. In minute amounts too low to present any health risk, drinking water will be tainted to the point it is undrinkable. Once present in ground water, it is extremely difficult to remove.

MTBE is being phased out as an oxygenating ingredient in the US. At the same time, the resultant surplus is being sold as an oxygenating ingredient for petrol production elsewhere in the world.

As per Power Equipment Australia s October/November 2001 Manganese leaves a red-red brown coating on all internal engine edition. MTBE has found its way to Australia and is already components and the use of MMT can readily be identified when being used in petrol Western Australia has already banned its use this condition is present. When used in petrol, if a clear/opaque due to potential contamination of precious drinking water. A January, 2001 AAA report supports prohibiting the use of MTB as well as Methanol and all other derivatives of alcohol (DIPE, ETBE, TAME, ETAE, etc.)
Another aspect of today 's fuel is octane ratings. With the elimination of lead in automotive petrol in 1986, other compounds have been to regain octane ratings. Alcohols do an effective job of raising octane. 10% methanol can raise the octane rating by 2-3 points. MTBE is also an effective octane booster. As petrol has gone away from tetra-ethyl lead as the most common octane booster, these other compounds are prevalent. Simple to remember-if lead is out, what is replacing it?
An additional characteristic of lead for a 4-stroke is that of providing a cushioning effect for valves to prevent valve scat recession. Other than as an octane booster, lead is unnecessary in a 2-stroke. As a result, several compounds have been substituted as a means of providing this protective layer:
M Mobil: manganese (MMT)

M BP: potassium

M Shell: Phosphorous

fuel container is used, the resultant reaction can lead to plugged fuel filters.

Potassium has the effect the gumming or sticking valves.

Phosphorous can have a similar effect, as well as leaving a sooty appearance on all internal engine components.

Sodium is also used in some over the counter octane boosters, but has been known to corrode internal engine components in certain high-temperature engine conditions.

Alcohol Shaker Test

To test for the presence of alcohol and the approximate percentage, a simple shaker test can be done to trigger phase separation. This can be done with a straight- sided glass cylinder or beaker with graduations on the side. Briggs and Stratton s P/NM 100023 Gasohol Test Kit is a commonly available and inexpensive tester. In summary, by adding a measured amount of water to trigger phase separation, the percentage of alcohol present can be derived by a separation line and the amount shown above the amount of water that was placed in the tube. Overall, a 10% ratio is considered acceptable, but serious problems will be seen if the amount is 20-30%.
Note: This test separates approximately 90% of the alcohol present. If the test result shows 10%, the actual is approximately 11 %. Caution: this tester is not effective if MTBE is present. Only laboratory test apparatus can be used to arrive at the percentage of


Australian Octane ratings:

LP (leaded petrol) 89 RON

Super (leaded) 95-96

PLP 98

ULP 91-92

LRP 96


RON research octane number taken at light load and under

MON motor octane number taken at high load and RPM

RON rating is used in Australia and NZ

RON+MON formula used in N. America 2

Australia / NZ octane numbers are higher than typical US numbers, but when the RON + MON method is used, octane ratings are very similar.

A higher MON number is considered to be a better performing fuel. RVP ( Reid Vapour Pressure)

A test and rating system used to measure fuel volatility. Propane and butane gas are commonly added at various levels to match a historical monthly temperature chart for each region of a country. Worldwide, this figure is normally in a range of 48-103 kPa (7-15) psi for regions with clear seasonal changes for winter and summer. The less the climatic variation between seasons, the lower the spread between summer and winter numbers. The only cause for concern is when an unseasonably warm day occurs or when fuel blended for a colder area is transported into a warmer climate.

Note: The standard RVP of Australian petrol is higher vs. RVP limits in the US, Canada and Japan. These are also primary markets for 2-stroke equipment, Many times simply adhering to good maintenance practices (clean cooling fins, intake passages, etc) will avoid the potential for vapour lock.

For the future, several air quality proposals are in process to reduce summer RVP in populated, industrialised areas such as Brisbane. One would reduce summer RVP limits to 65 kPa (9.4psi).

Fuel Recommendations

Use fresh fuel with at least a 91 octane rating
Recommend your customers use name-brand fuel that has given good performance in your area.
Avoid cut rate/economy brands
Do not store longer than 30 days (1 week in high temperature conditions).
Use fuel stabilizer if equipment must be stored for long periods.
Keep cylinder fins and cooling air intake areas clean.

30-11-2009, 06:10 PM
Been using fuel stabilizers for years for straight fuel as well as premix, there is no mystery with the chemistry this stuff works, have used stabilized premix 18 months old with no problems. I use it in every outboard I have in every tank.