Water in the fuel tank

[Robfaith]

Hoping not to sound like a complete idiot but having returned from 8 week hols our outboard would not start. Ginger has a built in tank and appears to be watertight but when the engineer tested the fuel from the tank it had water and dirt in it. The tank was supposedly washed out when the outboard had its first service. It ran well after this and had been fine. Engineered said that inboard tanks sweat and are always a problem...... Is this correct. Would love some feedback on this and if we should go with his suggestion of just putting the plastic fuel tank that came with outboard in the locker with lead running through hole inside of inboard fuel tank to link up with external fuel nipple already there . Not really happy with this idea. HELP!!

[Tales]

Hi Robin and Faith,

The term 'sweat' is a bit of a misnomer.
The air which enters your fuel tank as the fuel is used has water vapor held in suspension.
The watervapor condenses on the sides of the tank when the temperature falls below dew point.
The water then runs to the bottom.
The volume of water increases over time as more fuel is used until it reaches the fuel outlet and you motor cops it.
Good practice to drain/pump the bottom of the tank every now and then.

Loose tanks in lockers don't have the facility to drain/vent in the event of a spill/accident.
They are banned from all racing boats.

Good luck!

Tom

[Dolphin]

Tom is right, again.
If you're using e10 in marine environments the ethanol has a high affininty for water and drops out of solution producing a visible layer of water. Use straight petrol 95 octane or so.
You can add fuel additives to the fuel to get rid of the water, I think they're metho based, it dissolves it back into the fuel and burns it.
Your cars fuel tank has the exact same problems and probably goes through a greater temperature and dew range than the boat.
Portable fuel outboard tanks have a vent that can be closed. Is that a solution? Keeping your tank full if you are going away for extended times will reduce the air/fume exchange.
Diesel tanks have the same problem and the result is that the moisture supports the algae growth that blocks fuel filters. Its an awful black fluffy mould.
It also depends a lot on where you get your fuel. You may have picked the water and gunk up with the last load of fuel

[Troppo]

Hoping not to sound like a complete idiot but . . .

Haha, it is amazing how boats do that to ya. Good topic though.

My mad fishing mate who has been going a long way out to sea in small tinnies for decades puts a glass bowl filter (CAV I think) on his fuel line. Then he can see if there are any problems with muck collecting and it means he does not rely on his outboard filter to do everything. I was thinking of doing something similar sooner or later.

He does not use any additives in his fuel as he goes through it quickly, always fresh. Me, however, I like to put additives in to keep the fuel fresh for longer and stop the water from pooling under the fuel. Just bought a little bottle the other day and was shocked at the price. Worked out about $7 for 25 litres of fuel but then it is proctecting close to $40 of fuel and oil. Since I won't be able to use the fuel for a maybe 3 months I thought the money reasonable insurance. Might buy a big bottle next time as works out cheaper. I don't know how long it takes fuel to go off but I am cautious, if the motor fails, bit hard to row the old Top Hat.

[Dolphin]

G'Day Louis,
Petrol goes off in 6 weeks.
Diesel doesn't go off because it doesn't have any volatiles. It's just oil.
Those glass bowl filters are good, also known as aglomerators. They do pick up some of the water to be burnt but not in sufficient quantities to cause any problems. In diesels it also shows the mould.
They're good.

[Troppo]

Hi Greg, 6 weeks is not long. I have only just started using the petrol additive as previously I had a diesel motor. Used to put additive in that to keep the mold or whatever at bay.

[storm petrel]

I always use an additive when I add diesel to my tank (50 litre) and use a primary CAV before my the secondary filter on the diesel and have never had a problem.

In the bad old days of crappy old cars and long surf safaries I got caught out with water in my petrol a few times. I just cleaned out the fuel bulb, put a couple of cups of metho in the tank and cranked it back to life - problem fixed. Not sure if this would still work in these days of fuel injectors and computer controls but it was a sure fire fix back then. Wasn't it great when you could actually fix the car yourself. I must be getting old!

Happy Fathers Day,

Mark(grandpa)
Storm Petrel

[Dolphin]

I was told it was 6 weeks but here in a Briggs and Stratton Manual for the 4 stroke motor mower it says 30 days. If you use a fuel stabiliser it can be used up to 24months.

Briggs n Stratton storage.jpg (52.13 KiB) Viewed 3218 times

Diesel doesn't deteriorate, although a small BMW I was working on the fuel turned to gum and blocked the fuel lines.

[SeaLady]

I learned about E10 fuel the hard way.

Part of the refit of Sea Lady includes a fuel filter to remove water.
Also I only ever use premium fuel - Now!!!


Funny how everyone knows about this AFTERWARDS!!!!

I am interested in the fuel additives (fuel stabiliser) to make it last longer.
What is it and where do you get it?
Is it suitable for marine environments?

[Dolphin]

I imagine REPCO or some of the other stores would know about it. Or ring your local boat mechanic or dealer.

REPCO stands for
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