carburetion fuel delivery. purpose: produce mixture of fuel & air to operate an engine
TRANSCRIPT
CarburetionFuel Delivery
Purpose: produce mixture of fuel & air to operate an engine
Basics:1. Air enters top of carburetor2. Mixes with liquid fuel3. Goes through passages4. Sprayed into intake manifold5. Burned in combustion chamber
Operates based on different pressures
Cylinder has no atmospheric pressureAir/fuel mixture is pushed into cylinder by
atmospheric pressure in the carb
Venturi principle- Restriction in a passage creates a vacume.
( Causes air to move more rapidly)
Carbs come in many styles & typesNatural draft- air flows horizontally into
manifoldUpdraft- a/f mixtures forced upward
toward engineDowndraft- gravity assists air into
manifold
Float type carburetorsFloat= maintains constant level of fuel in
float bowl
When fuel is used float unseats needle valve and allows fuel to enter the bowl
Choke- Round disk mounted on shaft at the intake end of the carb.
Closed= provides more fuel to the engine to allow starting
Adjusting needle- adjusts the amount of fuel entering the nozzle to be discharged.
Sometimes these are pre-set & non adjustable
Primer- hand operated plungerForces additional fuel through main
nozzle. Mainly used to start cold engines
Governor◦Maintain a selected speed◦Prevent over-speeding that could cause engine
damage◦Limit high & slow speeds
Air CleanersEngines must have clean air!Dust/moisture ruin engines
Servicing an Air CleanerChange ever 25 hours on lawnmowersFollow manufacturers instructions