Suzuki outboard motors 1988 2003 repair manual., Page 67Get this manual
FUEL SYSTEM 4-5 of the low pressure in the venturiDepending on the model, there could be two, three or four bypass holes High Speed Circuit
ISee Figure 6
Three-eighths-wide-open throttle, as the throttle plate moves toward wide open, we have maximum air flow and very low pressureThe fuel is metered through the main jet, and is drawn into the main discharge nozzleAir is metered by the main air jet and enters the discharge nozzle, where it combines with fuelThe mixture atomizes, enters the venturi, and is drawn into the engineFig8 The V4 and V6 engines use solenoid release valve and large volume chamber for fuel delivery into the intake systemAIR04704G23
Fig6 The high speed circuitBASIC FUNCTIONS
ISee Figures 7, and 9
The carburetor systems on in line engines require careful cleaning and adjustment if problems occurThese carburetors are complicated but not too complex to understandAll carburetors operate on the same principlesTraditional carburetor theory often involves number of laws and principlesTo troubleshoot carburetors learn the basic principles, watch how the carburetor comes apart, trace the circuits, see what they do and make sure they are cleanThese are the basic steps for troubleshooting and successful repairThe diagram illustrates several carburetor basicsIf you blow through the straw an atomized mixture (air and fuel droplets) comes outWhen you blow through the straw pressure drop is created in the straw column inserted in the liquidIn carburetor this is mostly air and little fuelThe actual ratio of air to fuel differs with engine conditions but is usually from 15 parts air to one part fuel at optimum cruise to as little as parts air to one part fuel at full chokeIf the top of the container is covered and sealed around the straw what will happen? No flowThis is typical of clogged carburetor bowl ventIf the base of the straw is clogged or restricted what will happen? No flow or low flowThis
ATOMIZED FUEL
represents clogged main jetIf the liquid in the glass is lowered and you blow through the straw with the same force what will happen? Not as much fuel will flowA lean condition occursIf the fuel level is raised and you blow again at the same velocity what happens? The result is richer mixtureSuzuki carburetors control air flow semi-independently of RPMThis is done with throttle plateThe throttle plate works in conjunction with other systems or circuits to deliver correct mixtures within certain RPM bandsThe idle circuit pilot outlet controls from 0-Vs throttleThe series of small holes in the carburetor throat called transition holes control the Vs- throttle rangeAt wide open throttle the main jet handles most of the fuel metering chores, but the low and mid-range circuits continue to supply part of the fuelEnrichment is necessary to start cold engineFuel and air mix does not want to vaporize in cold engineIn order to get little fuel to vaporize, lot of fuel is dumped into the engineOn many older inline engines choke plate is used for cold startsThis plate restricts air entering the engine and increases the fuel to air ratioThe V4 and V6 engines use solenoid release valve and large volume chamber for fuel delivery into the intake system behind No2 and No.3 carburetors (V6 models), and No.1 and No.2 (V4 models) to ensure easy starting under all conditionsFuel for this system is delivered from the fuel pump (top pump on the V6) directly to the fuel starter valve assembly where it is controlled by float and inlet needle valveWhen the ignition key, in the ON position, is pushed in, the solenoid will open the solenoid release valve and fuel will flow to the two starter jet ports at the end of the carburetor boreTurning the manual valve counterclockwise, to open, will allow fuel to flow in the event of an electrical problemThe manual valve must remain closed during normal engine operation-