What The Fuel (WTF)!

[Adam_Winstone]

So, having a number of bikes there comes a time when some bikes get used less than others. Probably as long ago as 6 months, I parked up this bike in a perfectly reliable and road-worthy state and now the time has rolled around for me to MOT it again. Although I knew the battery for the original 6V DC system was failing to hold charge for long, I decided to give it the once over and ensure that my battery charger had put enough into it for the active supply when running to power the horn and brake light.

This morning I got up early to check that all was well for me to try and get it in for an MOT, only to find that the bike wouldn't start. Funnily enough, it did fire a couple of times (I kid you not) so I thought it might burst into life after a few more kicks, then a bump... but no Lift the seat and check fuel in tank (fine). Panel off to see that fuel is visible in the clear fuel line (fine). Swap out plugs again, checking for decent spark (fine). After many attempts I decided that stripping the carb might be a good idea... and look what I found!!!















Bearing in mind that the fuel in the tank looks fine, as does the fuel in the fuel line, how the heck can this be the state of the fuel in my float bowl?! I had this happen once before, decades ago, when leaving my bike out the back of my digs and finding that the oil separated from the fuel on cold nights, however, this is something else! When this happened, way back when, I was using good quality Rock Oil, today's example is on the same Groundsman that I've used without issue for a number of years and have never previously had a problem with.

Is this going to be another example of the fuel changing specification?

Your thoughts very welcome.... and take this as a warning to the rest of you that leave a bike standing for any length of time (if that is a contributing factor).

Adam

Edit: All parts cleaned out, then doubled cleaned with spray carb cleaner, the fuel flows freely from the tank/tap and the bike runs fine!

[purple_pill67]

W@nking in the carb?
(sorry, someone had to say it)

[Adam_Winstone]

No problem, although joking aside, if your goo looks anything like that then you may want to go and see someone about it!

[scooterslag]

that is pretty f@@king odd, could the fuel have a even higher amount of ethanol/additives which have a shorter shelf life?

[Adam_Winstone]

Feedback so far:

The oil in the carb has reacted because maybe it's reacted with the oxygen in the water and air drawn in through the carb vents? It's possible with such a small volume of fuel in an oxygen rich environment. Also, the fuel will contain ethanol, which could also be the reason for oxygenation. I would have to do a bit of research in to the fuel contents and the reactions involved.

Written by biochemist.

CONTINUED...

She did explain more but didn't write it down, she mentioned dissimilar metals in the carb, varying temperatures through the day is it in a warm garage subject to changes in temps day and night or and a humid environment the carb interior is subject to free radicals in the fluid all effected by the environment & temps it's kept in.
The fuel tank likely has a larger and much more different or stable environment altering the effects on the fuel.


Funny that she said about the range of metals in the carb as it looks as though the alloy of the float bowl has almost been etched with oxidization where the gel has formed, much like the white crust that you get when alloy casings weather/oxidize, and the brass body of the main jet holder has turned a slight purple colour where the gel has built up on it.

This is a regular science experiment!

Adam

[purple_pill67]

Haha.
Can you remember where you last fueled up?
Is your bike kept indoors/shed/garage/outdoors?
Mine is kept outdoors, covered over, but used every day which i hope stops anything like this from having chance to happen.

[purple_pill67]

Had you used Petseal or anything on your tank?

[Mr G in NYC]

welcome to my world Adam..... I have the same issues problems with Scooters
stored over the winter here in NYC. However since installing underfloor heat
system in my garage , I have to say I have had less issues , go figure .... It would
seem storing fuel in the scooter at very low temperatures cause's separation etc
and a small amount of heat seems to help alleviate these symptons . Also I have learnt
to run the carb dry after a run to ensure there is no fuel in the bowl or the fuel pipe .
This also seems to help . Thus when you start up from fresh the engine is burning off
the fuel straight away. Good news is that I've found a source for 100% octane aviation
fuel which I intend to use from now on G.

[Adam_Winstone]

No, I don't remember where I last filled up but the rest of the petrol mix in the tank allows the bike to run fine.

No, nothing used to seal the tank... 100% standard.

The scoot lives in a garage but it would have got very cold in there at times, which takes my thoughts back to this happening when my other scoot was outside in cold temps.

G... all you have stated rings true with me, although I've never had to run dry my bikes previously.

I wonder if this is a 'feature' of new fuels or something that I'd have suffered equally in the past. A couple of times on one bike over 25+ years makes me think that this was not a real problem in the past and I hope that it does not become a problem in the future.

Thanks for the feedback/comments.

Adam

[warts]

Presumably its the ethanol in the fuel, my meths camping stove does the same if I forget to empty it.
The chainsaw doesn't like fuel being left in at all, that goes gooey too, even with stabiliser.