Fuel back flow ?

[Robo62]

Hopefully an east fix?  1970 1100 xflow 

basically when left over night the fuel in the filter flows back and empty’s  causing it to take ages to start from cold. After running it for a while it will always fire up quick . It just doesn’t like being left overnight or for a long time. Sometimes I have to get it going on easy start or something like it . Any ideas?

[BaileyMex]

I'm sure there are others on here with a wider technical background to help, but would a non return valve help just before the filter?

[DT36]

50 minutes ago, Robo62 said:

Hopefully an east fix?  1970 1100 xflow 

basically when left over night the fuel in the filter flows back and empty’s  causing it to take ages to start from cold. After running it for a while it will always fire up quick . It just doesn’t like being left overnight or for a long time. Sometimes I have to get it going on easy start or something like it . Any ideas?

Maybe look at fitting a non return valve:

https://www.carbuilder.com/uk/search?q=Non+return+valve

 

 

 

Edited January 4, 2022 by DT36

[katana]

Something isn't right then as once the system, from tank, pipework, filter, pump to carb is primed and full of fuel it should not 'drain' back. To do so would create a vacuum in the line preventing it happening. If it is occurring, then there is an air leak and i'd suggest its likely to be the float valve. Reason being that, the float bowl is vented to air and weight of fuel will drag air past the float valve to displace the fuel flowing backwards. Either fit a 1 way check valve preferably a flap valve type before the pump or re-new the carb float valve. 

Edited January 4, 2022 by katana

[Brenda1978]

Had the same on a 16 xflow. Fitted return valves and new gaskets and stuff. For some reason the carb bowl never filled up. Put an electric fuel pump and better. Went to twin 40 webers and completely gone as was the petrol in the tank.