Quote:
Originally Posted by ol'George
Just remember liquid will seek it's own level and it will flow "up hill" it the input is above the output.
But I agree it is best to have a downward slope from tank to carb, but if it it not possible it will still flow liquid. 
The higher the tank in relation to the carb the better the flow, ---within reason. |
I wasn't going to go all 'science' on this, because - well, it's just a mower forum.
The issue with low sections of the fuel system are fuel vaporization. The vapor pressure of modern fuels is - junk. The vapor pressure of hot fuel is worse. the vapor pressure of hot, Ethanol fuel is abysmal. Now, we're not talking about drawing a lot of fuel, over a long distance, at a great height, but with the fuel just above a running engine, and the fuel line passing right next to the exhaust, best to avoid the fuel vaporization issue completely.
Now, if we want to use 100 Octane avgas, with a very high Reid vapor pressure, we could wrap the fuel line around the axles, and it would never have a problem. Ethanol blended fuel - well, no guarantees.