old fuel

[Hobes]

Just wondering how long we can keep boat fuel before it's "no good" ??

Someone told me the other day, 8 weeks... anyone any commments?? :P

[Mick]

I was told 4 weeks in North QLD, and even less in the hotter months.

[whiteman]

4 weeks!!! And how do you drain a 100+ litre tank of "old fuel"? There are plenty of times when you can't get out in NQ for weeks on end because of the wind. And these periods haven't affected the performance of my motor.

If you think the fuel is old, top it up with some new stuff and take it for a long run. I suppose if I'd had it in the tank for more than a year I'd think about it, but then I wouldn't deserve to own the boat in the first place.

[Mick]

Whitey, was told by my service provider. I was referring to a 20 Litre tank in my tinny. A mates Jenny failed yesterday because of dodgy fuel (too much condensation). The fuel was not that old either.
Maybe it depends on how the fuel is stored as well.
Kind regards,
Mick

[cooky]

I'm not sure how long it is, but I know that when I bought my boat a couple of months ago I had it serviced and the Outboard Mechanic smelt old fuel straight away - I must admit it did have a different smell. He was concerned because of fuel that it might run bad (carbs clogged) - he told me to drain the fuel and put fresh fuel in (even recommended Premium). I did this and took it out the next day - ran like crap under load. He cleaned the carbs that night and has run like a dream ever since.

[devocean]

For those who are unsure on what to do with old fuel you canuse it as weed killer which is what I do works great. You can always sell it to the townsville army barracks I hear they use it to train cats or something

[cooky]

Cats and Cane toads :-X

[Kerry]

4 weeks!!! And how do you drain a 100+ litre tank of "old fuel"? The best thing to do is not put it in there in the first place, something they call good fuel management practices.

The days of filling fuel tanks after a trip are long gone.

Cheers, Kerry.

[Big_Kev]

You can always sell it to the townsville army barracks I hear they use it to train cats or something

LOL, Thats a good one.

[skippa]

Yep,

Gotta agree Kerry, only fill her up when I'm going out. I have a 90LT tank and so far (5 years) I've never had a problem or felt the need to run premium fuel either.

The 'ol Yammie 115 2 banger hasn't missed a beat, and is no slouch for that matter either.


Cheers,
Tony 8)
PS sometimes I would have 40 to 50 LT's left and not go out again for anything up to 4 weeks.

[aido]

more fuel in a tank = less air space = less condensation buildup.
all the same i always fill up before going out, like kerry says.
can't trust the memory cell anymore. lol.

[whiteman]

In the perfect world, fuel management would be easy. In my world, the trip gets planned, the fuel goes in and either the weather changes or the seas are higher than anticipated or we catch fish on the inner shoals, or whatever. And up here, you need a large margin for error as you can go out all day and not see another boat.

Having said that, I don't think the motor has been idle more than 6 weeks!

[Oldyella]

Mick is "On the money" with the 4 weeks in the hotter climate. A full tank is better.. and you should always add some fuel conditioner such as Petrolpower (From Whitworths) or similar marine additive to minimise gum and reduce water intrusion. Another product is Fuelset and is recommended by the BIA. You only use about 250ml per 1000L. I have used it with my 2 stroke Merc to keep it from developing a "Lean condition"
http://www.liquideng.com.au/fuelset.html

[435_Mark]

I've got a Yamy 50HP fourstroke and right at the start I decided to run it on premium. Big mistake! I thought the higher octane premium would be a cleaner burning fuel with a more controlled burn that would be better for the motor. However, I had problems on a trip up in NT with the oil low pressure horn going off, rough idle when trolling and hard to start. The yamys run a 10W -30 oil and I initially thought I would get around the problem with a thicker oil. Changed to normal unleaded first to double check and no more problems.
Anyone know of a site that give some info on the actual chemical differences between the fuels?

Mark

[DavidT]

Ok here is one for you all,

For an old 72 Model Evenrude, can you put Premium in it to give it a little clean out? will it cause any damage to the engine for having such an octaine charged petrol?

It has just had a major service, and still has all its compression 150psi I think he said, and it runs quite well, except it doesnt like to travel at anything under 8kn it gets really jumpy.

And when is fuel classified as old, is it Colour? Smell? or do you just purely go by age?

Cheers,

David.

[435_Mark]

David,
Old fuel reeks. If the fuel is off it smells very musty, oily and like old varnish. Believe me if the fuel is past it's use by date you will know with one sniff. If your boat is stored in a cool place (under cover) it will last heaps longer.

Cheers,

Mark

[billfisher]

Fuel only has a short life if it is the premix variety (ie has 2 stroke oil mixed in). What happens is the the oil goes off when mixed with petrol. This happens after about 8 weeks, I have heard. Straight unleaded lasts much longer, about 4 months or more. All that with happen to it is that the octane rating will drop a bit as the more volatile components are the first to evaporate (although moisture in the fuel can cause problems).
If you are going to store premix fuel for longer than 8 weeks all you have to do is mix in a fuel stabiliser and it will last for 12 months.
Don't use premium fuel with premix 2 strokes as the oil is not fully soluble due to its different chemical composition.

[billfisher]

[

[DavidT]

David,
Old fuel reeks. If the fuel is off it smells very musty, oily and like old varnish. Believe me if the fuel is past it's use by date you will know with one sniff. If your boat is stored in a cool place (under cover) it will last heaps longer.

Cheers,

Mark

Thank you Mark,

I will keep an eye on that, i am compiling a list of things to look at now and then, and also to assist me in doing my regular checks prior to hitting the water, this way i can avoid mid water break downs.


Fuel only has a short life if it is the premix variety (ie has 2 stroke oil mixed in). What happens is the the oil goes off when mixed with petrol. This happens after about 8 weeks, I have heard. Straight unleaded lasts much longer, about 4 months or more. All that with happen to it is that the octane rating will drop a bit as the more volatile components are the first to evaporate (although moisture in the fuel can cause problems).
If you are going to store premix fuel for longer than 8 weeks all you have to do is mix in a fuel stabiliser and it will last for 12 months.
Don't use premium fuel with premix 2 strokes as the oil is not fully soluble due to its different chemical composition.

Thank you BillFisher,

Going to head my way down to the local mariner when they open up again, and check out the variety of fuel stabolizers and then compare them on the Internet and get users feed back, this way i can be sure i am using stuff that is proven to work right.

Appreciate everyones feed back.

Cheers,

David.

[Kerry]

The problem with storing fuel? Simple! don't store it at all, basically problem solved.

The water arguement is a non event as that can be managed far better than bad fuel.

Cheers, Kerry.

[Dignity]

Kerry, I have a 200 litre tank, what do I do with what's left after a trip which can vary from 30 - 100 litres. Maybe I need to come up with a system that pumps nitrogen into the tank voids and seal off the air breathers to stop the fuel going off.

[Kerry]

Kerry, I have a 200 litre tank, what do I do with what's left after a trip which can vary from 30 - 100 litres. #Maybe I need to come up with a system that pumps nitrogen into the tank voids and seal off the air breathers to stop the fuel going off.

Mate, something that is called fuel management. Some (bad) days even with oil injection I'll oil my tanks (both of them and you think 200 litres is a problem :o), and depending on the day it could be 100:1, 150:1 or whatever but this is done "as required", based on the conditions as being experienced, not as expected.

Some trips one might mix PULP, other times simply ULP depending the intervals between trips. With underfloor tanks one should really have spare fuel, which is simply that, "always" spare and can be easily used for something else. Trying to retrieve fuel from an underfloor tank when murphy's law is in force is not the thing one ever wants to do.

Cheers, Kerry.

[Dignity]

Kerry, willing to learn. What do you mean by "I'll oil my tanks"? I thought adding oil was a sure fire way to reduce the life of petrol or have I read it wrong. I agree with the Spare fuel comment, mine usually ends up in the mower or the car after a trip.

[Burley_Boy]

There are two real issues that easily get confused here. The first is old fuel and the other is water in the fuel. If you get water in the fuel from condensation, rain or evil children :o then you don't need much water to give you grief. The water settles to the bottom of the tank around your fuel pickup (at least in the 20lt plastic tanks we initially talked about). This water is the reason for the crappy running in many cases as it tends to congregate in the wrong parts of the carbie rather than just running through.
I'd say get a water separator if condensation is an issue, the old fuel has never made mine run differently but I don't use premix just unleaded and seldom has it stood more than 4 months but it would be close at times. This is just my experience with my outboard and I have never successfully added additives to get rid of water in the fuel. Its a simple task to clean out a 20lt tank and check the fuel if you're having dramas but start by checking the fuel filter this will show the water first in most cases.

[Kerry]

....What do you mean by "I'll oil my tanks"? #I thought adding oil was a sure fire way to reduce the life of petrol or have I read it wrong....

Premixed fuel certainly has less of a life than straight fuel but this has all to do with looking after the outboard not worrying about a bit of fuel going bad.

Different outboards have different strategies as some systems mix the oil/fuel different to others, some mix before the carbie, some mix after, some really don't mix at all but inject direct. In crapy sea conditions with systems that run "pure" fuel through the carbies a "bit of oil" can help lube things as a "bit of oil" can help counter the sometimes lots of water that outboards do injest. A little more oil is certainly better than not enough, especially where water is concerned.

On the subject of water, water (condenstation as such) can be controlled much better than bad fuel apart from the times where water becomes overpowering and it's times like this that somebody has simply stuffed up or the fuel station has simply piss... in your fuel tank (this has been known to happen).

But as far as condenstation is concerned it's really a non event with properly fitted filters/separators and really the correct (recommended) method to fit fuel filters is 2 per line/per motor in series and drained after EACH and EVERY trip. #

Cheers, Kerry.
# # #

[QldKev]

I also use some metho in my fuel tanks every 3 months, being alcohol based it absorbs the water and passes through the system. A lot of the water absorbers on the market are alcho based.

435_Mark when you ran PULP in your engine and had lower oil pressure could have been not from the dilation of the fuel into your oil. It may have been the higher the octane giving a longer burn time, resulting in a flame front in your exhaust manifold, creating extra heat; thus thinning out your oil.