Fuel dilema

[vRSG60]

I filled my S3 tank back end of last week and drove a mile or so home. On Saturday 2 of us rode to Whalley and back, total 30 miles max. On the way back, after covering about 16 miles my scooter slowed right down, I switched to reserve and everything was fine again. When I got home I looked in the tank and the level had dropped about 3 inches or so, well above the level of the fuel tap I'd have thought.
I've experienced this many times. It seems it doesn't take long for the fuel to stop flowing unless I put the tap on reserve??
Any thoughts as to why this should occur? All I can think is maybe it's a poor flow tap that needs a good head of fuel unless switched to reserve.

Whatever fuel economy seems nowhere near what I was expecting. 80 MPG+

[dapper]

Check hole in petrol cap handle is clear. Disconnect fuel line from carb and drain into a graduated jug timing how long a pint of fuel takes to drain. Should be 1 pint a minute (assuming you have a fast flow fuel tap fitted). If less, then take apart fuel tap and check for no debris inside and rubber gasket has correct size holes that line up correctly with holes in ally body. There is often a difference in the fuel flow rate between normal and reserve.

[Tommy Boy]

Is it a fast flow tap? Some have long 'reserve' pipes meaning they hit reserve early and you still have a good amount of fuel left. I normally unscrew the filter and shorten the pipe to a sensible length before fitting

[Timbo]

I have a 11.5 litre tank and a fast flow tap. I hit reserve after 60 miles and probably have as much left as used. As pointed out you probably have a long reserve pipe.

[cezeta]

this is a possability.....

although there is nothing in the tank ive had it a few times (including this weekend on mrs cezetas vespa which got aa d home) where a silt substance builds up in the tap or carb.

it happened to mrs cezetas tap, i had it blown out with an air gun but this time its the carb itself thats blocked. she has a kawasaki zephyr 750 too and thats had the same.......must be make up or something.

the reason it fails half way through the tank is the weight of the fuel is no longer pushing the fuel through

i would buy a new high flow tap as they are peanuts, you symptoms can cause a seize or holed piston

another story i heard today is that modern pifco fuel is buggering the carb floats making them leak and fill up with fuel, this stopps the needle opening.

[cit205]

all been said before probably but some interesting reminders on here

http://www.frost.co.uk/protect-your-veh ... st-ethanol