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[Music]
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when you finish this program you will
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understand the operation of the ve pump
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so you can relate to service and
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troubleshooting
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instructions some of you will repair or
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calibrate this pump on the test bench
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some of you will make minor pump
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adjustments on the vehicle
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all of you will know what you're doing
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and
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why why is the ve pump important to
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you this late model distributor type
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pump will be found in growing numbers in
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passenger cars imported and built in the
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United
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States in other applications such as
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light Marine small industrial and
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agricultural as you'll be seeing more
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more and more diesels and more ve pumps
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to
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service what is a ve
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pump the V comes from ver Tyler meaning
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distributor it's also called a rotary
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pump it's more compact than most
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familiar Diesel Injection pumps the
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governor and Supply pump are not
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external they're inside the
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ve the inter integral Supply pump keeps
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the interior filled with diesel fuel not
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lubricating oil but fuel Under Pressure
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we'll show that in
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Orange under control of the pressure
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regulator Supply pump pressure Rises
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with RPM to as much as 100 PSI about 7
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bar the ve pump can lift fuel directly
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from the tank through the
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filter some fuel bleeds through an
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overflow to carry away heat back to the
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tank like a spark ignition distributor
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the diesel pump starts the power stroke
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with proper timing and distributes to
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each cylinder in firing
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order in the ve pump the single plunger
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operates with two motions rotation and
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stroke in the center of the distributor
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head the rotating plunger distributes
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high pressure fuel shown in red to one
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Outlet passage every 90° in this
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4-cylinder
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application High pressures May average
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around 2800 PSI about 200
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bar as the distributor slot lines up
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with each passage it delivers High Press
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fuel from the center of the
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plunger you'll find various models of ve
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pumps with distributor heads and Outlets
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matching the number of engine
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cylinders so distri distribution by
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rotation is one job of the plunger
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system fuel metering is another job to
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understand fuel metering let's look at
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the stroke
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motion plunger stroke is constant in the
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ve pump but the rollers don't lift on
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the cam it's really the other way around
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as the plunger and cam plate rotate they
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lift on the rollers and are returned by
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the
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springs from bottom dead center you can
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see the constant plunger stroke as cam
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plate and plunger lift on the rollers to
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top dead
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center in our four-cylinder cam plate
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there's a cam lobe lift within each 90°
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sector if you consider the rollers as
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fixed you can see the cam plate and
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plunger rise up on the rollers to TDC
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and return to BDC
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look again at the two motions of the
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plunger stroke and
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rotation you can see the plunger May
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dwell at BDC before and after the stroke
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but even during the dwell plunger
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rotation is
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continuous that's important because
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during the rotation The Fill Port lines
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up and opens one of the fill slots
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bringing in fuel for one cylinder the
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port then closes
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we know that Port closure is related to
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timing and metering of fuel delivery
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let's see how remember the motion of the
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plunger it stroke to TDC and return and
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its continuous
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rotation the plunger fills with Supply
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Pump Fuel shown in Orange during
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pre-stroke while it's still at BDC
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after rotation to Port closure the
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plunger lifts from BDC and begins
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delivery at high pressure shown in
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red the distributor slot delivers High
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Press fuel through a delivery passage
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and line to each cylinder in firing
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order there the fuel injector needle
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opens and fuel is
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delivered how does this delivery stop
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that's the job of the metering
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sleeve as the plunger Strokes through
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the metering sleeve the movement
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uncovers a spill Port opening the high
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press circuit and spilling the remaining
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fuel into the pump
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interior this is called Port opening or
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spill effective stroke ends with Port
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opening even though plunger stroke
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continues with the drop in pressure the
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injector cuts off
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delivery aided by its delivery valve at
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the pump distributor
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head so for each plunger rotation and
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stroke we have fill to Port closure
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delivery to Port opening and
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spill for a 4-cylinder engine we have
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four plunger Strokes in one pump
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Revolution 360° which is of course 720
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engine
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de the ve pumps we've been discussing
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are called zero
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pre-stroke because Port closure occurs
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by rotation before the plunger lifts
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from
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BDC you can identify these pumps by the
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simple fill slots which Port close by
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rotation contrast the zero pre-stroke
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with the plunger of a different pump
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which has a
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pre-stroke because of this anulus or
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circular slot The Fill Port cannot close
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by rotation
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alone instead the plunger must lift for
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Port closure only after the annulus
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lifts Beyond The Fill Port do we have
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Port closure
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for this type of V pump lift to Port
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closure settings are important because
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delivery does not begin until a
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specified lift from
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BDC regardless of Port closure Port
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opening is determined by the position of
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the metering sleeve as the plunger and
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spill Port move through it the metering
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sleeve position determines the amount of
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fuel
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delivered what positions this sleeve
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it is usually the accelerator pedal some
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form of power control
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lever for low power light accelerator
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pressure the sleeve is closer to BDC so
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the spill Port opens sooner by plunger
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stroke for greater power the sleeve is
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farther from BDC so the spill Port does
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not open until later in the plunger
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stroke so as this lever positions the
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sleeve it determines the effective
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stroke the effective stroke is always
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less than full plunger
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stroke it is the spring and fly weights
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which determine the force on the
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governor lever and
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sleeve when does the governor
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control you may recall it controls at
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start low idle full load rated Speed
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high idle and overrun or coasting for
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each case let's see
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how at startup the fly weights are at
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rest so the guide bushing is pushed back
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to the left in this
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picture the governor lever pivots to
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move the metering sleeve the other way
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away from
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BDC then how does that affect fuel
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delivery for
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startup that's right maximum delivery at
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startup spill occurs only after the
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plunger takes its longest stroke to Port
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opening when the metering sleeve is
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farthest from BDC the effective stroke
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is
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longest so for startup the greatest
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quantity of fuel is delivered greater
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even than at full
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load now as the engine starts the fly
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weights open out moving the guide
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bushing to the right so the governor
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lever pivots the sleeve to the left
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shortening the effective
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stroke with the sleeve close to BDC the
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plunger moves only a minimum distance
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before the spill Port opens thus a
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minimum effective
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stroke at low idle the governor controls
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fuel injection at the idle RPM tending
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to compensate for temperature and load
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changes
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when you increase power move from low
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idle to high-speed stop what
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happens fuel delivery depends on a
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balance of forces spring forces
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balancing flyweight forces pivoting the
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lever to move the metering
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sleeve when you're increasing power
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spring Force tends to move the sleeve
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away from BDC against the opposing
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flyweight
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Force the fly weights are collapsed at
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low RPM and at full load the spring
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force is greater than the flyweight
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Force the metering sleeve is moved away
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from BDC so the effective stroke is
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longer the fuel quantity per stroke is
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greater the engine accelerates and the
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vehicle gains speed
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in part speed is determined by load
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climbing a hill full load may be at some
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paral speed between minimum and
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maximum as the RPM approaches rated
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speed what
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[Music]
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happens at rated speed and full load the
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spring Force just balances the flyweight
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Force holding the metering sleeve for
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rated speed delivery
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full load continues at rated speed but
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no
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more now suppose you run the engine at
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no load as with the clutch down and
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accelerator full down holding the
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control lever against the high idle or
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maximum rpm
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stop at high RPM the fly weights move
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out opposing the spring the fly weight
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force is stronger so through the lever
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it moves the metering sleeve to reduce
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effective
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stroke this reduced fuel flow is called
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high idle notice this no load condition
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produces a maximum rpm faster than rated
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speed but at a fraction of the fuel
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delivery finally suppose you release the
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accelerator and Coast returning the
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governor lever to the low idle stop what
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happens
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at high RPM with accelerator at idle the
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flyweight Force overcomes the relaxed
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spring the metering sleeve moves so
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close to BDC that injection pressure
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never develops a zero delivery
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condition zero because the metering
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sleeve is so close to BDC that it never
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covers the spill Port during the plunger
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stroke zero delivery during overrun is
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one reason diesels are so economical
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during conditions such as City
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driving you've seen that at full load
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the governor lever moves the metering
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sleeve far from
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BDC how can we make a full load
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adjustment say to increase our full load
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fuel
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quantity on the governor you'll find a
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full load adjustment screw you should
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adjust this screw only on the test bench
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never on the
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vehicle this screw adjusts a special
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lever called the correction lever
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pivoting at 0. one notice this
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correction lever carries pivot two the
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normal pivot point you've seen for
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spring and flyweight force on the
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metering
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sleeve so moving this full load
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adjustment screw shifts pivot 2 which
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has the effect of Shifting the metering
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sleeve and so changing our full loadad
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delivery on the test bench you can turn
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this screw to move the correction lever
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inside the
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pump this movement in to increase pivots
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the correction lever at pivot 1 to move
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pivot 2 and the metering sleeve
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increasing the effective stroke and
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therefore the full load fuel
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delivery you can see why this full load
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fuel delivery must be adjusted before
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the other
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settings high and low idle can be done
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on the test bench or on the vehicle in
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the shop set idle RPM at the low idle
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stock set maximum rpm at the high idle
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stock but leave the full load adjustment
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screw
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alone you've seen distribution and
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metering in the ve pump will conclude
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with injection timing the timing
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mechanisms and the timing
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adjustments in a procedure similar to
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spark timing Diesel Injection timing is
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adjusted to the engine by rotating the
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pump housing around the drive shaft
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axis timing is set by turning the pump
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in the mounting bolt slots so injection
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begins at the correct
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time in this cutaway ve pump you can see
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the timing device the timing piston and
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its opposing
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spring at low RPM Supply pump pressure
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has little effect on timing piston
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travel as pressure Rises with increasing
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RPM piston movement advances the roller
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ring opposite to drive shaft
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rotation this advances the time when the
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cam plate will lift from BDC to begin
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the stroke
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so as Supply pump pressure increases
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with RPM the timing piston travels
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advancing the time when injection
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Begins for this reason procedures on the
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test bench include measuring the travel
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of the timing piston as the RPM
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changes on some ve pumps a cold start
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lever and cam Advanced the timing a few
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degrees tending to reduce startup smoke
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on most pumps fueled shut off is
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electrical a solenoid valve closes the
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supply of fuel to the fill port and the
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plunger you may find a mechanical shut
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off the lever system overrides the
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governor spring to move the metering
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sleeve to zero
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delivery you've seen the compact ve pump
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pressurized by the integral Supply
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pump the single plunger rotating for
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distribution of fuel to the cylinders in
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firing
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order you've seen the meter delivery to
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Port opening and
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spill the metering sleeve opening The
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Spill Port sooner for lower power
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requirements or set to open later for
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greater
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power position by the accelerator spring
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forces and Governor
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flyweights governed for correct delivery
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quantity at various load and RPM
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conditions finally you've seen the
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timing and the timing piston
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travel operating principles important to
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your service and troubleshooting
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instruction brought to you by VOS
