Small external tank for outboard

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FL390

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I've just learnt the hard way about petrol going off both in the tank and the carb.

I have a 12 litre tank, but even this is too big for the amount of use it gets. (6hp on the back of my sail boat to get out of the marina and that's it. 30mins - 1 hour use max every 2 weeks).

I can't find any on the internet, but has anyone seen a 5 ish litre tank? Or more appropriately for this forum has anyone converted a petrol station Jerry can?

What might I need to think about?
A valve to equalise the pressure. A tube to suck the stuff up. Am I missing anything? I'm surprised a tank this size is not in more demand.
 
I sympathise. I have looked to find something like that without success. I have a different reason for looking, however: MADRIGAL’s 2.5 HP Yamaha outboard has a small gravity-feed tank inside the engine cowling that gives her a range of about 4nm at 4 knots. This is more than adequate for getting in and out of the club’s basin, and we use less than 4 Litres over an entire sailing season. There have been occasions on cruises, however, when leaning overboard from a heaving deck with funnel and jerry can to refuel in a seaway has been less than enjoyable, and I have wished for the sort of small, external tank that you describe to give a bit more steaming range between refuelling. Do let the Forum know if you find such a thing.
As an aside, on one occasion, trying to refuel while being tossed about by the wake of motor cruisers on a busy bank holiday week-end, we boosted code flag Bravo at the starboard spreader: Taking on, discharging, or carrying hazardous cargo. Had I slipped, we would certainly have discharged fuel overboard. Predictably, I suppose, the flag had absolutely no effect on the passing traffic, who may have been a bit rusty on the International Code of Signals.
 
Could you not just fit a dip tube and vent into a 5 litre fuel can, use small standard bulk head fitting and length of tube and use a screw vent,
 
I've had problems with dried out fuel in the carb but never so far, when in the tanks. The tanks are left though with vents shut, so it does keep the vapour in which is possibly one of the components that makes petrol work. There are others on here with much more knowledge about petrol than me so I might be wrong .....
 
MADRIGAL said:
I sympathise. I have looked to find something like that without success. I have a different reason for looking, however: MADRIGAL’s 2.5 HP Yamaha outboard has a small gravity-feed tank inside the engine cowling that gives her a range of about 4nm at 4 knots. This is more than adequate for getting in and out of the club’s basin, and we use less than 4 Litres over an entire sailing season. There have been occasions on cruises, however, when leaning overboard from a heaving deck with funnel and jerry can to refuel in a seaway has been less than enjoyable, and I have wished for the sort of small, external tank that you describe to give a bit more steaming range between refuelling. Do let the Forum know if you find such a thing.
As an aside, on one occasion, trying to refuel while being tossed about by the wake of motor cruisers on a busy bank holiday week-end, we boosted code flag Bravo at the starboard spreader: Taking on, discharging, or carrying hazardous cargo. Had I slipped, we would certainly have discharged fuel overboard. Predictably, I suppose, the flag had absolutely no effect on the passing traffic, who may have been a bit rusty on the International Code of Signals.
Click to expand...
Carry reserve of fuel in a container which actually pours, with a spout or neck which will go into the outboard's filler.
Personally, I tend to carry a 5l can of fuel up and down the harbour, and I will top up the motor alongside the yacht, therefore never needing to refill mid harbour.
For a small fuel reserve, you can get one litre aluminium fuel bottles, some camping/mountaineering types use them for petrol-fired stoves.

And carry some oars....
 
Thanks for that! Aluminium fuel bottles like the ones for camp stoves would be perfect for safely topping up my motor’s little petrol tank if I had to do it under way. They could also be a solution to the OP’s desire not to have a large quantity of fuel to go stale.
 
I had a similar problem. 5HP outboard, used to get in/out of marina, so used about 4 litres a year. Found using super premium fuel 97 or 98 octane solved problem. Extra cost trivial, I think it had a lower ethanol content but cannot prove that is why.
 
crewman said:
I had a similar problem. 5HP outboard, used to get in/out of marina, so used about 4 litres a year. Found using super premium fuel 97 or 98 octane solved problem. Extra cost trivial, I think it had a lower ethanol content but cannot prove that is why.
Click to expand...

Your Octane rating is derived partly from the Ethanol content added ... to boost it. Ethanol is used as it reduces CO2 and CO emissions while still retaining octane rating. It allows lower rated base gasoline to be used in the blend.

One aspect of Gasoline across the EU is the use of MTBE - which vaporises off if you do not seal your container.

Another is Butanisation - where Butane gas is introduced to the blend.

The reason your 97 - 98 seems better for you - is because of the higher rating ...

Reference storage and gasoline going 'off' ............... that's a storage matter you should easily control. Avoid plastic containers ... avoid heat ... avoid light.
Plastic containers actually allow migration through the plastic ... its fine for short term storage but not long term. Its why we are not allowed to retain samples in plastic bottles - they must be glass or metal. Plastic containers are usually not able to seal sufficiently once opened.
Heat - I think anyone can imagine that a summers days will substantially increase vaporisation of light ends from the gasoline ... cause gum deposits to drop out ...
Light - this is actually similar in effect to heat ... and is why we use dark medicine glass coloured bottles for samples.

We store in cool dark areas and its good for months ... year in fact.

I have no problem with my outboards ... I run all carbs dry at end of day. I close all vents on tanks. I put away in my barn till spring and never have any problem at all. The old fuel runs as good as last day used ... I only use cheapest 95 from local station ... (E5).
 
You might find this from Esso in 2019 useful.

What is the ethanol content of your fuels?
The majority of unleaded 95 Octane petrol sold in the UK contains up to 5% ethanol as required under the Government’s Renewable Transport Fuels Obligation (RTFO).

There is currently no requirement for renewable fuel (such as ethanol) to be present in super unleaded (97 grade petrol).

Esso super unleaded petrol (Synergy Supreme+ Unleaded 97) is ethanol free (except in Devon, Cornwall, the Teesside area and Scotland). We would therefore advise anyone who has concerns about the presence of ethanol in petrol to use Synergy Supreme+ – providing they do not fill up in Devon or Cornwall, the Teesside area or Scotland.

Our Synergy Fuels:
  • Diesel
  • Supreme+ Diesel
  • Unleaded
  • Supreme+ Unleaded
 
Thanks for the replies. Most important is to keep it cool, dark and in glass. As I can't do that I'll opt for Esso 97 and also purchase some additive.

I'm still keen on the Jerry can 5liter tank idea. For one I can fill it up at the petrol station without getting told off. If I get a chance o we the summer will see what I can make. On that basis I will only be able to fix from the outside of the can. What adhesive would work for this? I understand the plastic they are made of can be tricky to glue.
 
FL390 said:
Thanks for the replies. Most important is to keep it cool, dark and in glass. As I can't do that I'll opt for Esso 97 and also purchase some additive.

I'm still keen on the Jerry can 5liter tank idea. For one I can fill it up at the petrol station without getting told off. If I get a chance o we the summer will see what I can make. On that basis I will only be able to fix from the outside of the can. What adhesive would work for this? I understand the plastic they are made of can be tricky to glue.
Click to expand...
I thought of making/modifying a cap with a breather and dip tube. If one had a couple of identical 5L fuel cans, it could be switched from one to another.
Maybe machine a brass disc to sit in the neck of the can with an o ring to seal. Use the plastic collar which comes with the pouring spout to clamp it in place.
I never got around to doing anything about this idea, Instead, I just bought a 12 litre outboard tank from Pacer Marine and got on with life. That was a reserve tank for my RIB.
My tender outboard runs for long enough on a tank, provided I fill it up before a long leg up the harbour. That's about as long as I want to listen to an outboarrd TBH.
 
OK ... going back to schoolboy tactics ....

How to fit a sealing collar and outlet into a bottle / can .... (its also how you single handed fit through hulls on a boat !)

Get a sealing outlet from shop ... basically a threaded tube with a large washer like ring at one end with rubber sealing ring. It has a nut to thread on with another washer and rubber ring to seal.
How to get that tube through the hole you cut into the can ?

You can either fit it to the screw on cap but then you'll probably have a leak when you invert can to use it ! or do the old ship in a bottle trick ...

You drill small hole each side opposite each other in the outer end of the threaded tube ... pass thread through both holes and tie as a bridle leaving a long length ... tie a small weight to that end ...

Now having cut the hole in your can to suit the threaded tube .. you make sure rubber sealing ring is fitted to inside end of fitting ... drop the weight on end of thread into can and rattle it round till it falls out the hole ... now holding can with hole uppermost ... you carefully pull the thread and tube through the hole ... pass outer rubber ring .. washer and nut over the thread and fix in place. The small holes even let you jam a nail or similar in so you can hold that while tightening the nut to make sure all sealed.

Matter of then just getting required connector to fit your fuel hose ...
 
FL390 said:
Genius - thanks for that write up.
Click to expand...

The other trick for bolts using similar ... is to grind the end of the bolt with two flats creating a head that a spanner can hold. ... Drill hole through the flat for the thread ... pull up through the hole ... pass nut over thread and wind onto bolt ... to tighten take spanner to that ground head and bingo ... bolt is held while you tighten.
 
I've used the Honda additive for about 5 years now and not had a problem with my Honda 2.3 outboard, I don't run the carb dry, even when laid up over winter. Mind you I haven't started it yet this year!
 
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