left over fuel

**icecutter** · 25-02-2006, 22:56

Ive herd old fuel should not be used. is there Any thing that can be done to reuse old fuel.ive got three 6g tanks full with oil in.........

**Dave.S** · 25-02-2006, 23:53

Hi Ice

There is a lot of talk about how long unleaded lasts or not, depending on your point of view.

What I have found is that as long as you keep the tanks air tight as you can is seems to work ok on my Mariner 4-stroke. If you look on the RON rating for outboards they can be very low and if you have every been to the USA the petrol they sell there is a low rating.
Whether RON rating has anthing to do with this I don't know but from a practical point of view i rotate my tanks so I always use the oldest first and don't refil/top up a tank until the day I use the boat.
I always carry a spare gallon in a separate can "just in case" and top a tank up with this every 3 months.

So far I have never had a problem but then again I use neat petrol and not 2-stroke.

Hope this helps

Dave

poppajoe · 26-02-2006, 00:33

Hi,
I have used old petrol succesfuly but a few things to consider for certain are.

how old are we talking about?
There must be no water (condensation) present at all.
What are you going to use it in? I use my oldest petrol to run my seagull auxillary, they run on anything, but I would not put it in your new fict or efi??
However when ever I use it I tend to mix it with good at 60/40 (40 old).
It's down to personall preference I suppose, but if in doubt - throw it out, as problems can be very costly even more than 18 gallons of fuels worth.

If all else fails - sell it a lawnmowerman or such like?

**blueskip** · 26-02-2006, 17:59

My philosophy:
If it splutters & farts, & then it starts,
& it runs out the tank, who gives a ****!
Where do we draw a line under the "sell by date", at almost one pound per litre who in their right mind can afford to give their fuel to the local gardener?
Not me thats for sure, if the engine starts & runs, then the fuel is fine! At a pound per litre, plus 4 pound per litre for Quicksilver 2 stroke oil, its far too bloody expensive to cut the lawn with!
blueskip

poppajoe · 27-02-2006, 21:09

Originally Posted by blueskip

My philosophy:
If it splutters & farts, & then it starts,
& it runs out the tank, who gives a ****!
Where do we draw a line under the "sell by date", at almost one pound per litre who in their right mind can afford to give their fuel to the local gardener?
Not me thats for sure, if the engine starts & runs, then the fuel is fine! At a pound per litre, plus 4 pound per litre for Quicksilver 2 stroke oil, its far too bloody expensive to cut the lawn with!
blueskip

Hey Blueskip - I mean't sell it to the lawnmowerman, man I would not give it away, I would keep it to light bonfires first!!!!!!

**ChrisP** · 27-02-2006, 21:22

In a tightly sealed can it will be OK. The problem with unleaded is it contains a lot of volatile fractions to boost the octain level. These evaporate in the open, ie a carb and leave behind the heavier fractions. That is why the carb gets gummed up. As long as it has been stored in an airtight container it will be fine.

The problem with having oil premixed in it is that it will settle somewhat depending on how long it has stood. Give it a really good shake up to mix it.

If you are worried connect the tanks to the engine and start it on the muffs or in a tank of water. It should prrov the fuel for you and set your mind at rest.

Audrey S · 27-02-2006, 21:29

I was told by an engineer recently;

"When you wash the engines thru using the muffs, to disconnect the fuel lines from the motor and run them until they stop as this emptys the carburettors and eliminates a lot of the gumming up problems"

Maybe of use to someone

Regards

Ubd

**ChrisP** · 27-02-2006, 23:16

I have heard 2 schools of thought on that Urly, the first is to leave the carb full which I tend to do. There is more fuel to evaporate and therefore it takes longer to go gummy. The second as you say run it out lbut you will always leave a drop of fuel, and a lot of air space for it to go into.

No definitive answer but as I say I tend to leave the carbs full on mine during the season and have not had a gummy one yet, touch wood.

poppajoe · 28-02-2006, 00:11

Originally Posted by urlybird

I was told by an engineer recently;

"When you wash the engines thru using the muffs, to disconnect the fuel lines from the motor and run them until they stop as this emptys the carburettors and eliminates a lot of the gumming up problems"

Maybe of use to someone

Regards

Ubd

It's a difficult one this - I was told by a good marine engineer that you should not run them out on multi cylinder engines as you could get the same problem as when damage occurs from running one cylinder too lean and causing piston burn etc.
I had a mercury blueband once that burnt the top piston out due to running with a weak fuel pump and it was not supplying fuel to the top carb (there were 3 of them), although this was caused while running normally - could the same happen on tickover?
I too have never suffred from leaving the carbs full? what I do like to do last thing is rev up and turn the ignition of while it dies down thereby leaving unspent fuel in the system?
I wonder if an outboard engineer on the forum has any advice / theories?

**icecutter** · 28-02-2006, 01:54

thanks for all your help folks...with all the info ive received , i think im not going to take the chance running my main engine (mariner 60) ..i have a spare seagull ill use as my backup so i can use the fuel in that