OT - sort of: Indicator for water in petrol

May 29, 2017 4 Replies

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Graham J 9 years ago

Lawn mower running rough. Previously this has been caused by a few drops of water in the carburetter's float chamber.

But now I think my jerrycan may have some water in it because having drained, cleaned, and re-filled the mower's fuel system it is still running rough.

Is there an indicator I can add to a sample of the fuel to show whether there is water present? Ideally something like a food dye which I might already have in the kitchen?

Is there a way to make a small amount of water dissolve in the petrol so the engine will run properly? So I can flush out any water in the system.

TIA

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Chris Whelan 9 years ago

If any of those things existed, they would cost more than 5 litres of fuel.

Dispose of the crap fuel sensibly, buy a new can and fill it, clean the carb. Job done.

Chris.

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Harry Bloomfield 9 years ago

Graham J wrote on 29/05/2017 :

Unlikely it will cause it to run rough, it will either run or not run. Water is not that combustible.

The petrol will not mix that easily with water, the fuel will float on top.

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Graham T 9 years ago

Pour it down the drain and throw a match in for a laugh.

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newshound 9 years ago

Agreed. Always worth draining the float chamber if you suspect this. Empty the jerrycan into a bucket, if there is excess water you should be able to see it. Decant off the "good" petrol and discard the last bit. When lubricating oil contains water above the solubility limit it will look "cloudy".

If the petrol looks cloudy (I have never seen this, but I suppose it might happen if your can has been contaminated with detergent or similar) you could add up to 5% meths. This should dissolve the water, and the mixture will mix with the petrol. It should burn OK in a lawnmower.

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