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condensation in fuel tank

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condensation in fuel tank

Posted by george_phillips at October 11. 2018

I've noticed a small amount of white smoke when the throttle is blipped and  - I'm told - when running normally. I fellow NOC member suggested water in the fuel tank.

I coupled this thought with the fact that when I re-assembled everything after a few weeks lay-off whilst I sorted the oil pressure system, the bike seemed really "punchy". It went well and sounded good.

Without rushing to my text books I think when water is boiled off into steam it occupies about 13 times more volume hence increasing the pressure in the combustion chamber.

So the questions are:

Should I leave it alone as it's aiding the performance of the bike ('55 ES2)?

What would be the negative effects of leaving well alone?

George

 

 

Re: condensation in fuel tank

Posted by michael_sullivan at October 11. 2018

You can be running te risk of rotting out the bottom of your fuel tank

Mike

Re: condensation in fuel tank

Posted by john_oldridge at October 11. 2018

Hi George

I don't think water in the petrol tank is the cause of your white smoke, most engines, (bikes and cars) emit quite a bit of moisture (condensation) when the engine is cold from the exhaust, and it should disappear  when the engine is up to running temperature. If it persists when hot, it could be  excessive oil consumption, (what color is the spark plug after a run?).

My M50 always goes better on a dull day when the air pressure is higher. After  the Austrian rally when I went up the Grossglockner pass (two up! 2500mtrs) It  didn't pull quite as well, because of the lower pressure.(or could it have been because my wife was on the back!!!!)

Try and run on fuel with no ethanol in and you will help remove all water from the tank, If you had a lot of water, the bike wouldn't run anyway, as it always tends to  separate, and  goes  to the bottom, then  causes  the tank to rust.

Regards John O 

Re: condensation in fuel tank

Posted by ian_soady at October 12. 2018

I thought one of the criticisms of ethanol (misplaced in my view) was that it actually held water in suspension (or maybe solution)? So wouldn't that just allow it to pass harmlessly through the engine?

But where does this water come from anyway?

I remember when there were water injectors on the market which were supposed to increase performance. Cold damp weather should indeed increase the weight of charge going into the combustion chamber and enhance performance, even if only minimally.

Re: condensation in fuel tank

Posted by john_shorter at October 12. 2018

I don´t know much about modern aircraft engines, but the transport aircraft I worked on in the RAF used water-methanol injection ( the methanol was only for anti-freeze ) to increase power on take off.   The water, if any, in the tank comes from condensation ( like dew ). 

Re: condensation in fuel tank

Posted by richard_hudson1 at October 12. 2018

It has always been known that engines developed more power when it was foggy but because it was foggy you couldn't take advantage of it. The reason for the extra power was that hydrocarbons in the fuel are normally un-burnt  and pass out with the other products of combustion. By adding water vapour these hydrocarbons become combustible producing extra power.

In the 50's and 60's we would experiment with home made water injection systems (usually felt pipe cleaners stretched across the carb. bell mouth and fed from a small container of water strapped underneath) they did show small improvements but insufficient for the mess on required.

Dick 

Re: condensation in fuel tank

Posted by david_cooper at October 12. 2018

My old friend told me water injection caused engine internals to rust! (Not surprising, really!)

I do sometimes wonder about collecting some of those silica gel packets that arrive inside boxed goods, and putting them in a mesh basket (like a tea infuser) and hanging it inside the top of the tank when the bike is in the shed (in such a way that it has to be lifted out when re-filling.)  That might reduce winter tank corrosion.  But I always put an old towel over the tank when in the shed to prevent condensation both outside and (hopefully) inside.

 

As for water with ethanol in fuel - the allegation is that first it takes water into solution, and then the water separates back out and sits at the bottom of the tank.  Problems are worst in places with hot, humid climates, where boats (in particular) suffer.  GRP tanks are dissolved by the stuff, and steel ones rust.  Madness!

Re: condensation in fuel tank

Posted by robert_tuck at October 12. 2018

I put a strip of masking tape over my filler cap breathers and this seems to stop the evaporation of the volatile elements and the constant movement of moisture laden air. The temperature remains fairly constant . The slight pressurisation this causes can make taps leak,so i check regularly.If you move bikes around then the vents need to be open.

Re: condensation in fuel tank

Posted by george_phillips at October 12. 2018

I'm drifting a bit off topic here but to comment on John's points, I think you'll find that bad weather is usually associated with low - not high - pressure and the reduced power at altitude would more likely be attributable to the lower density of the air resulting in less weight (or mass) of oxygen being pulled into the combustion chamber on each inlet stroke.

I forgot to mention that I do pour an anti-ethanol additive into the tank whenever I refuel as I live in Cornwall where E0 does not exist (as far as I know!)

Maybe it separates out the water?

Re: condensation in fuel tank

Posted by john_oldridge at October 12. 2018

George,

I was never any good at physics, I am just pleased my slow progress up the Grossglocker, can be blamed on atmospheric pressure and not my passengers (and my) weight.........Ha Ha.

Esso supreme (plus) doesn't contain ethanol................at least not in Yorkshire!  

Regards John O

Re: condensation in fuel tank

Posted by george_phillips at October 13. 2018

Next time you're out you can get me a few gallons, John. As far as I know Cornwall (or at least my part of it) doesn't stock Esso Supreme (plus). Have you ever read "Zen and the Art of M/cycle Maintenance"? Heavy going but in the book he explains how he had to re-adjust his carb as he went up into the mountains 'cos of the reducing air density. Out of interest the air density at 2500 m is 73% of that at sea level so your engine is pulling in 27% less oxygen into the c/chamber hence your M50 not pulling so well.

George

Re: condensation in fuel tank

Posted by john_shorter at October 13. 2018

Having attended the Colombres Rally, (4 times) in Spain, I can certainly confirm loss of power at higher altitudes.  Some of the runs, into the mountains, were over 2,000m. above sea level.  The poor Dominator was gasping for breath!

Re: condensation in fuel tank

Posted by dan_field at October 13. 2018

Previously George Phillips wrote:

Next time you're out you can get me a few gallons, John. As far as I know Cornwall (or at least my part of it) doesn't stock Esso Supreme (plus). Have you ever read "Zen and the Art of M/cycle Maintenance"? Heavy going but in the book he explains how he had to re-adjust his carb as he went up into the mountains 'cos of the reducing air density. Out of interest the air density at 2500 m is 73% of that at sea level so your engine is pulling in 27% less oxygen into the c/chamber hence your M50 not pulling so well.

George

 

Funnily enough the book was an answer in the telegraph pub quiz today,.... nailed that one!

Re: condensation in fuel tank

Posted by george_phillips at October 13. 2018

Well done Dan. Just show how this Forum helps in so many ways......!

 

George

Re: condensation in fuel tank

Posted by nigel_keating at October 13. 2018

Previously ian_soady wrote:

I thought one of the criticisms of ethanol (misplaced in my view) was that it actually held water in suspension (or maybe solution)? So wouldn't that just allow it to pass harmlessly through the engine?

But where does this water come from anyway?

I remember when there were water injectors on the market which were supposed to increase performance. Cold damp weather should indeed increase the weight of charge going into the combustion chamber and enhance performance, even if only minimally.

My understanding is that Ethanol has an affinity for water. i.e it will draw water from the atmosphere. When the ethanol is saturated, the ethanol/water mix separates from the petrol and sits at the bottom of the tank. This mix is a weak acid.

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