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View Full Version : Vlx fuel pump delete with elevation changes



Hawk421
05-20-2015, 8:57 PM
I know a lot of you guys are running without fuel pumps however is anyone doing this in places with big elevation changes ? I live in Washington state with lots of these fun changes

JetBlackII
05-20-2015, 11:33 PM
I know a lot of you guys are running without fuel pumps however is anyone doing this in places with big elevation changes ? I live in Washington state with lots of these fun changes

The only thing elevation does is thin the air, meaning there's less oxygen in it... this in turn affects combustion. Unless it's diesel... the fuel must be atomized or mixed with air to burn, the vapor of gas is flammable not the fuel itself unless you mix it with air in a mist to burn.

A fuel pump just delivers fuel to the bowls, the same as any hose with a petcock does... under mechanical or atmospheric pressure makes no real difference the carbs don't really care. So if you decide to go to gravity feed... the likely change is re-adjust on the A/F screw... and or possibly T-the fuel line to both carbs instead of one.

The fuel pump just makes sure the float bowls are always full instead of relying on gravity to fill them up... depending on how the carbs are setup. Gravity feed can starve a bowl from poor flow to it... float bowl starvation can even happen in other bikes with no fuel pump because of improper hose lengths feeding them or cause a difficult start up on the side opposite of the kickstand, because fuel isn't at the proper level in that/those bowl(s).

There are small inline fuel pumps to be found, if you like the anti-starvation benefits a fuel pump offers... but gravity feed no matter the elevation sans outer space, still works just fine to feed fuel.