How to find and fix a fuel leak?

Mike W

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Feb 20, 2002, 3:40:45 PM2/20/02

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I've got a problem with an occasionally leaking fuel system on our family
run-around - a 50cc Suzuki FM50 landie scooter, oldish but with few miles on
it and happy to run at its glorious max of 30mph. When left in the garage
it eventually leaks fuel - it may take two days to show but when it shows
there is plenty of it - and I can't see where it is coming from. The fuel
pipes to the carb are OK and there is no sign of a leak at the fuel cock/tap
(with On, Reserve and Prime positions but no Off). The drain screw on the
carb float chamber seals OK - I tried that first as the fuel was pooling
under it. The carb is a Mikuni VM14SH, single. Anyone any hints as to what
I might try?

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BykrDan

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Feb 20, 2002, 5:14:33 PM2/20/02

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Hi Mike;

I'm just guessing, but I would bet the vacuum-actuated fuelcock is letting
fuel run to the carbs, even when there is no vacuum, or, like I did once,
you leave the fuelcock on "Prime" all the time, and flood the carburetor
bowl.

Either way, it should be a simple test to remove the fuel line where it
attaches to the carburetor. With the engine off, no fuel should be flowing
from the fuel line.

If this turns out to be the problem, you may want to change the oil right
away - fuel can run past the carbs, into the cylinders, past the pistons and
into the crankcase where it mixes with and seriously thins the oil (I'm
assuming a four-stroke engine).

BÿkrDan.

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zac

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Feb 20, 2002, 5:34:10 PM2/20/02

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I had the ol' fuel petcock problem last year, I couldn't find the source of
my leak but after a few day my Suzuki would be sitting in a pool of
flammable! Thought my carbs were the problem turned out not, Finally I took
the fuel petcock apart and an O-ring was distorted, had to buy the whole
fuel petcock but was well worth it....problem fixed.
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Feb 21, 2002, 2:37:36 PM2/21/02

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>I've got a problem with an occasionally leaking fuel system on our family
>run-around - a 50cc Suzuki FM50 landie scooter, oldish but with few miles on
>it and happy to run at its glorious max of 30mph. When left in the garage
>it eventually leaks fuel - it may take two days to show but when it shows
>there is plenty of it - and I can't see where it is coming from. The fuel
>pipes to the carb are OK and there is no sign of a leak at the fuel cock/tap
>(with On, Reserve and Prime positions but no Off). The drain screw on the
>carb float chamber seals OK - I tried that first as the fuel was pooling
>under it. The carb is a Mikuni VM14SH, single. Anyone any hints as to what
>I might try?
>

Clean thoroughly, then dust liberally with talcum powder (or chalk,
flour, cocaine etc.) Any leaks will show up in the powder.
This works a treat for oil leaks too.

Leslie Hammond

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Feb 21, 2002, 2:48:50 PM2/21/02

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"Mike W" <mi...@walkroul.freeserve.co.uk> wrote in message
news:a511c2$hmh$1...@news8.svr.pol.co.uk...

> I've got a problem with an occasionally leaking fuel system on our family
> run-around - a 50cc Suzuki FM50 landie scooter, oldish but with few miles
on
> it and happy to run at its glorious max of 30mph.

Add a on-off valve to the fuel line.

Fit was me, I'd also add a large see-through inline fuel filter. Oldish
metal fuel tanks always involve rust flakes. It's easier to deal with the
results instead of cleaning and lining the tank!