Deterioation of stored fuel

[BlueSkyNick]

Had a few problems with the tender's outboard (Mariner 3.3) last summer - I don't think it had been used for well over a year. I have now stripped and cleaned the carb, changed the plug and dumped the old petrol that was in the tank.

I mentioned this to a friend, who had been told by somebody else that petrol "goes stale" in only a month, so anything in an outboard for well over a year is bound to cause problems. This is why so many lawnmowers are difficult to start in the spring. So I haven't put any new petrol in it just yet, because I don't want similar problems when I come to use it later in the year.

Does anybody know if this is true? If so, does the same apply to diesel in the main tank? The recommendation is to keep the tank full during the winter to prevent condensation, but if it goes stale like petrol then will this create a different problem?

<hr width=100% size=1>OK - Get Fell In you 'orrible lot! There's wine to be drunk!

 

[Chris_Robb]

Nick - there have been lots of posts on this over the last year. Generally petrol looses some of the more volatile bits so keeping it a long time is not good. Having said that, I have kept fuel for over a year and never found any problems. If you have an old seagull, it would probably be more susceptible.

Even so its good practice to run the Carb out when you leave it for a week.

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[Talbot]

Leaving an engine for a long time creates several problems;
Fuel goes stale
Fuel in the carb evaporates leaving a sticky residue. this will go if carb cleaner fluid is used, otherwise it will affect mixture and generally screw up the running
cylinders can eventually go rusty
oil in the rings gets sticky affecting compression
etc.

So now you have another excuse to take your toy out and play with it!! /forums/images/icons/smile.gif



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[ex-Gladys]

Actually the Seagull would mind least. Unleaded deteriorates fast, and can be "off" in 6 weeks. Seagull wouldn't mind because it's low compression, and the carb jets are not measured in microns! Modern carbs will not emulsify the fuel as well, and the goo will gum up the tiny jets and passages. It's called progress...

<hr width=100% size=1>Larry Botheras

Anderson 26 "Amber"

 

[Omatako]

This interests me. I recently left a car in storage for 7 months and it started first touch and ran out the remainder of the fuel (leaded) without a hiccup.
My experience with outboards (or any other two stroke engine) is that the "residue" that remains is the oil which is left in the carb and pipes after the fuel has evaporated off. This will eventually be dissolved into fresh fuel and cause no problem but that could be some wait.
I have always (and still do) let the engine "run out of fuel" after shutting off the supply and my outboard (5hp Evinrude) always starts easily the next time.
I have never thrown away any fuel.

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[Guest]

Storage of fuel

Gasoline should always be stored in a dark and sealed container in cool conditions. If the gasoline has vented tank - it will lose its aromatics and light fractions .... BUT the main point has already been made by another - 2T fuel is susceptible to gumming up from the 2T oil more than the gasoline.
The more modern gasolines are blends of all sorts of components and not the single refined one of yester-year ....

I use old fuel, new fuel and all-sorts - and don't really have a problem That is with Mariner 3, Johnson 4.5 and my old trusty Perkins Diesel.

As regards Diesel .... this is a lower grade and heavier type of fuel than vapourous gasoline and literally shouldn't worry too much about storage. Yes it is marginally better to keep in similar conditions to gasoline .... but really don't worry.

So the main thing again .... sealed dark containers in a cool store.

If you think I'm wrong .... the average storage / transport time on any petroleum is weeks - even months in some cases .... so where is the case for the argument + the transport / storage is NOT sealed .......


<hr width=100% size=1>Nigel ...
So WHAT does the EU really stand for ????/forums/images/icons/cool.gif

 

[VicS]

Re: Storage of fuel

I also prefer to use metal containers as polyethene is permeable to oxygen and I have a theory that oxidation of the some constituents of petrol may also be a factor. Some of the lighter components may be also be lost through the polyethene. I expect you use glass or metal containers for samples, I always did.
I would, for the same reason, try to store only full containers ie exclude air

I always store outboard fuel from one year to the next but I always filter it at the start of the new season. I have an in-line filter in my siphon tube for that very purpose. The one time I did not do so I had to strip down the carb. in the dark in the entrance to the Medina river! It was probably the 2T oil that was to blame.

<hr width=100% size=1><font color=purple>Ne te confundant illegitimi.</font color=purple>

 

[ex-Gladys]

Re: Storage of fuel

Having had to take apart several Jap bike (4 stroke) carbs that have been "left" too long, it is most definitely not 2t oil... Petrol will turn to a jelly and eventually to a varnish, both of which cause the problem....

<hr width=100% size=1>Larry Botheras

Anderson 26 "Amber"

 

[oldharry]

Re: Storage of fuel

Petrol is stored in air tight containers, therefore will not evaporate off as the air space above rapidly becomes saturated with vapour which does not allow for further evaporation. Carburettors are vented which allows the petrol to evaporate off altogether, and leave residues known as varnish which are sufficient to cause partial or total blockage of the jets. Varnish does not dissolve back into the fuel and is very difficult to remove. 2 stroke oil dries out more slowly, but with much the same effect in the longer term.

The answer seems to be to run the carb dry before leaving it - BUT: - in a stroke the fuel carries the only lubricant the engine bearings get. Modern 2strokes are already on the edge of underlubrication at 50 or 100:1 mixes, so that running the carb dry leaves the engine without lubrication for the last few moments - having already starved it of oil as the mixture weakens..... not a recipe for long life!

4 Strokes of course have separate oil supplies and can be run dry with impunity.

Yet another excuse for taking the boat out more often.....?

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[Guest]

Re: Storage of fuel

2 Stroke engines many have oil injection now and NOT mixed .....


<hr width=100% size=1>Nigel ...
So WHAT does the EU really stand for ????/forums/images/icons/cool.gif

 

[Guest]

Re: Storage of fuel

Nowadays samples are stored in various media included HDPE plastic.
But many containers are subject to non-sealing caps .... so still it is Inspection Co. prcatice to use metal or glass containers ... preferably green or brown coloured glass bottles for Gasolines etc.


<hr width=100% size=1>Nigel ...
So WHAT does the EU really stand for ????/forums/images/icons/cool.gif

 

[Guest]

Re: Storage of fuel

Can't comment on jelly or varnish - as haven't seen that happen and I don't know of a lab method that could reproduce that ? We do a test for Existent Gum which gives content and possibility during storage - I can say that this is normally a very small amount in a standard gasoline ....

The only time gum and other would be increased is in blended fuels where some components may not be best available - there are some companies that bulk out fuels with all sorts of rubbish ..... has anyone noticed the disgusting smell to some gasoline nowadays ????


<hr width=100% size=1>Nigel ...
So WHAT does the EU really stand for ????/forums/images/icons/cool.gif