HL service manual
Contents
1. diameter channel welch plug is used Itis not necessary to remove this plug Carefully pry out welch plug then clean discharge ports and cross channels Now install new part 02531 1 thick welch plug by placing it in casting shoulder convexed side upward then flatten diameter 1 32 to a tight fit with a 5 16 diameter flat end tool TROUBLE SHOOTING Carburetor Floods 1 Dirt or foreign particles preventing inlet Remove clean and replace needle from seating 2 Diaphragm lever spring not seated Remove lever and reinstall on lever dimple 3 Diaphragm improperly installed in Replace diaphragm or correct installation carburetor Engine will Not Accelerate 1 Idle adjusting screw set too lean Enrich idle adjustment 2 Incorrect setting on diaphragm lever Reset 3 Diaphragm cover plate loose Tighten 4 Diaphragm gasket leaking Replace 5 Main fuel orifice plugged Remove diaphragm cover diaph ragm lever and main adjusting screw Clean out orifice by blowing through main adjust hrea le Engine Will Not Idle ment threaded hole 1 Incorrect idle adjustment Reset to best idle 2 Idle discharge ports or channels clogged Blow out with compressed air or if com pressed air is not available clean and flush with gasoline 3 Diaphragm lever set incorrectly Reset daiphragm lever so it is flush with the floor of the diaphragm chamber 4 Throttle shutter cocked in the throttle Reset bore caus2. it is then delivered into the mixing passages The vented side of the metering diaphragm may be vented either directly to the atmosphere or in the case of a balanced carburetor may be balanced internally vented to the choke bore The balanced type can be recognized by a brass tube in the choke bore which is connected internally to the vented side of the diaphragm The purpose of internal balance is to offset the enriching or choking effect of a partially dirty air cleaner Some carburetor metering systems include a ball check type main nozzle These can be identified by the brass cage located in the venturi choke band of the body casting The ball check valve allows fuel to flow into the mixing passage and prevents air from flowing into the metering chamber The movement of the pump diaphragm draws fuel into the fuel chamber and a reverse movement of the diaphragm forces fuel out of the fuel chamber through the inlet needle and seat into the metering chamber Movement is caused by pulsation from the engine acting on the diaphragm A plastic turret type inlet connection is the cover to the fuel strainer section of the carburetor and can be rotated 360 degrees for any required fuel connection location The strainer consists of a fine mesh screen to insure clean fuel supply to the metering section of the carburetor ADJUSTMENT INSTRUCTIONS To properly adjust carburetor for best performance the engine must be thoroughly warm INITIAL ADJUSTME
3. velocity of air through the venturi creates a low pressure area at the venturi throat and diminishes the suction on engine side of the throttle shutter When the pressure at the venturi throat is less than existing within main diaphragm fuel chamber fuel is drawn up through main fuel adjustment orifice and out main fuel discharge port into air stream entering engine intake VENTURI MAIN FUEL DISCHARGE MAIN ADJUSTMENT SCREW ORIFICE a Er be Dl fh DHR Ag RA HIGH SPEED OPERATION As the throttle shutter progressively opens from intermediate position to full open position the air velocity through the venturi increases and fuel is metered up through main fuel adjustment orifice and main fuel discharge port in accordance with the power requirements of the engine The action of the main diaphragm is the same as previously described with suction required to operate the diaphragm being transmitted through the main fuel discharge port SUPPLY FUEL ATMOSPHERIC AIR FUEL UNDER PRESSURE PUMP IMPULSE AIR FUEL UNDER VACUUM HOW TO DISASSEMBLE FOR CLEANING AND REPAIR The model HL carburetor can be cleaned under adverse conditions working on a clean surfac with a minimum of tools Before disassembling carburetor it is IMPERATIVE to flush it clean of sawdust and dirt by pouring gasoline over it and tools 1 Remove strainer cover retaining screw and plastic cover Remove strainer cover gasket and strainer scree
4. NTS To start a cold engine first carefully close by turning clockwise both idle and main adjustment screws Open main adjustment screw counterclockwise approximately one and one quarter 114 turns Open idle adjustment screw three quarters 4 turn Back idle speed regulating screw off its contact with throttle stop lever then turn it inward about one 1 full turn so as to slightly open throttle shutter Open fuel line shut off valve close choke shutter partly open throttle shutter and pull starting cord When engine fires open choke shutter slightly and idle the engine Do not race engine Then as engine warms open choke shutter To start a warm engine it should only be necessary to pull starting cord if the carburetor is properly adjusted FINAL ADJUSTMENTS Completely close throttle shutter and readjust idle speed regulating screw so engine idle speed is approximately 1200 RPM for lawn mowers 2000 to 2500 RPM for chain saws then slowly readjust idle adjustment screw to obtain smooth and even engine performance Poor acceleration may result from setting the idle mixture too lean DO NOT FORCE ADJUSTMENTS INTO SEATS MAIN FUEL DISCHARGE PORT MAPHRAAGIA CHAMBER REATI JIA FH Ranh mA PHA AGM BUTTON STARTING CHOKE OPERATION Starting an engine with the HL Carburetor involves the same methods that are used in a conventional float feed carburetor However since a diaphragm carburetor does not have the advantage o
5. RING lt ADJUSTMENT IMPULSE CHANNEL SCREW OMMorson
6. Series Service Manual oMMorson TILLOTSON LTD Clash Industrial Estate ralee County Kerry Ireland Ref No SM I INTRODUCTION The gasoline engine industry s universal acceptance of Tillotson s original diaphragm carburetor has resulted in the development by Tillotson engineers of the HL Series carburetor Designed with a minimum of parts this lightweight compact carburetor includes an integral fuel pump and filter in one small unit The all position mounting feature allows a wide range of possible applications Information contained in the following pages is presented as an aid to understanding construction operation and servicing of the HL series carburetor HL SCHEMATIC 1 Fuel Inlet 2 Fuel Pump Body 3 Fuel Pump Diaphragm SA Diaphragm Pump Inlet Valve 3B Diaphragm Pump Outlet Valve Fuel Pump Gasket Diaphragm Gover Gasket Metering Chamber Idle Adjustment Screw Impulse Channel Idle Fuel Adjustment Orifice 10A Primary idle Discharge Port 108 Secondary Idle Discharge Port 11 Throttle Shutter 12 Main Fuel Adjustment Orifice 13 Body 14 Venturi 15 Main Fuel Discharge Port 16 Choke Shutter 17 Fuel Inlet Supply Channel 18 Inlet Needle amp Seat 164 Copper Gasket 19 Main Adjustment Screw Inlet Tension Spring Inlet Control Lever z ANAA E Fulcrum Pin j i i NS Atmospheric Vent Hole 3 do 4 Diaphragm Cover 28 60 Gi 2 a 3 6 Atmospheric Chamber Strainer Gaske
7. USTMENT SCREW OR PRIMARY OLE F DISCH AGF Bea Tt _ iDLE FUEL SUPPLY SHANNEL glaf La IDLING OPERATION When engine is idling throttle shutter is in a partially cracked position Engine suction is transmitted through the primary idle fuel discharge port to the fuel chamber side of main diaphragm via the idle fuel supply channel Again the main diaphragm is forced upward by atmospheric pressure depressing the inlet control lever overcoming inlet tension spring pressure and permitting fuel to enter through inlet seat by forcing inlet needle offits seat contact and filling the fuel chamber side of main diaphragm The fuel is then drawn up through idle fuel adjustment orifice and delivered to the engine through primary idle discharge port VENTURA MAIN FUEL DISCHARG POAT ae T ONDA PY IDLE FUEL DISCHARGE PORT MAIN ADJUSTMENT tal Eu 21H MAIN DIAPHRAGM SOREW ORIFICE coe 0 Pl FUEL PUMP DIAPHRAGM INCLUDING INLET amp OUTLET FLAPPER VALVES FUEL STRAINER SCREEN FUEL STRAINER GASHET INTERMEDIATE OPERATION Fuel is delivered into and through the carburetor in the same manner as when the engine is idling However as the throttle opens and engine speed increases more fuel is demanded from the carburetor and supplied to the engine by valving in the secondary idle discharge port located immediately behind the throttle shutter As the throttle shutter continues to open and engine speed increases the
8. er rim to insure correct instal ee lation and operation Pump Diaphragm must a PUMP GASKET be clean and free of breaks or punctures ATMOSPHERIC DIAPHRAGM Diaphragm Gasket Main Diaphragm and VENT COVER Diaphragm Cover Casting must locate on cast pins at the body rim to insure cor MAIN _ rect installation and operation Main Dia DIAPHRAGM Zphragm must be clean and free of breaks or punctures lts metal disc must not become IDLE SPEED DIAPHRAGM bent and should always retain tight fit to REG SCREW GASKET ubberized body section BODY __ CONTROL LEVER motoring To inspect and clean Inlet Needle and Seat first remove Fulcrum Pin and Control Lever then inlet needle The Inlet Seat can now be carefully removed with a 5 16 hex socket wrench CAUTION If Inlet Seat is not handled with re the small Insert may fall out unnoticed INSERT E fall iced PE Remove Gasket and replace with new one GASKET before reinstalling Inlet Needle and Seat a by reversing above procedure WELCH PLUG g Welch Plug must seal tightly IDLE DISCHARGE PORTS L FULCRUM INLET NEEDLE CONTROL SPRING 4 Press in place flush with e BRASS ines body casting METERING CHAMBER Ni CHOKE SHAFT FRICTION PIN _ INLET SEAT Drain Plug PLUG die Discharge Ports must be open Screw must seal tightly SCREW PACKING PIN WASHER SP
9. f a great reservoir of fuel upon which to operate the technique changes somewhat When starting a cold engine place the choke shutter in the closed position and throttle shutter in a cracked or open position Several pulls on the starter may be needed to raise the fuel pressure to the required amount As the engine is pulled through with the choke in closed position engine suction will be transmitted to the diaphragm fuel chamber through both primary and secondary idle discharge parts as well as the main fuel discharge part creating a low pressure area on the fuel side of the main diaphragm Atmospheric air pressure on the opposite side will force the main diaphragm upward causing the diaphragm button to depress the inlet control lever overcoming inlet tension spring pressure permitting fuel to enter through the inlet seat by forcing inlet needle off its seat contact then into the fuel chamber side of main diaphragm up through the idle and main fuel supply orifices and channels and out the discharge parts to the engine In starting an engine that has been idle and not running for more than an hour it will be necessary to operate and maneuver the choking mechanism for approximately three 3 to ten 10 seconds depending on how cold the engine has become The length of time spent warming the engine is only necessary to the extent that the engine can be made to idle accelerate and run satisfactorily under wide open throttle conditions OLE ADJ
10. ing fast idle 5 Dirty nozzle check valve Clean or replace 6 Welch plug covering the idle discharge Replace welch plug following instructions ports does not seal This causes the engine outlined in service hints to idle with idle adjustment shut off Engine Runs Out Lean 1 Tank vent not operating correctly Clean if possible or replace 2 Leak in fuel system from tank to pump Tighten or replace fittings or line 3 Ruptured fuel pump diaphragm Replace 4 Main fuel orifice plugged Clean Carburetor Runs Rich With Main Adjustment Shut Off 1 The diameter nozzle channel plug or Install new plug or new cage nozzle check valve cage is not sealing NOTE INMAKING CARBURETOR ADJUSTMENTS TURN ADJUSTMENTS CAREFULLY AND GENTLY DO NOT RAM ADJUSTMENTS INTO SEATS Set engine idling speed in accordance with engine manufacturer s recommendation TROUBLE SHOOTING e Fuel Inlet Line must be tight COVER Be sure all SCREW COVER Remove Cover Screw Cover Gasket and Pump Body il screen Thoroughly clean Screen with clean Screws are gasoline or by blowing through with com tight to insure BODY SCREW a pressed air Install Screen next to Pump perfect seal E a SCREEN Body casting then gasket Hold Cover in at the parting Tom meme place and tighten Cover Screw surfaces PUMP BODY PUMP Pump Gasket and Pump Diaphragm must DIAPHRAGM locate on cast pins at Underside of Dia i n Cov
11. n Remove screws and fuel pump body Remove fuel pump diaphragm and gasket Remove main diaphragm cover plate Remove main diaphragm Remove main diaphragm gasket on Gm oO ff amp NO Remove inlet control lever fulcrum pin lever and tension spring 9 Remove inlet needle 10 With a thin wall 5 16 Hex socket carefully remove the inlet seat Remove inlet seat gasket When reinstalling seat tighten only from 25 35 inch pounds or 34 Kg Cm 11 Remove idle and main adjustment screws 12 When reinstalling O ring type adjustment screws lubricate with 30 SAE oil to prevent seizing Packing spring type adjustments do not require lubrication 13 The ball check type main nozzle can be removed by tapping it out of the body casting into the venturi with a small punch A replacement ball check nozzle should be pressed into the casting with the cross holes in line with the main adjustment needle The brass cage should be pressed flush with the metering chamber casting Before reassembling the carburetor in reverse order as outlined above wash ALL component parts in clean gasoline and blow off with compressed air The channels in the metering body should be cleaned by blowing through the idle and main adjusting orifices All fuel passages in the three castings should be cleaned with compressed air Do not clean orifices or passages with wires or drills as this might cause damage and incorrect operation of
12. t Fuel Inlet Screen NOTE On some models a one piece Idle Adjustment Screw ref 7 amp Strainer Cover Retaining Screw Main Adjustment Screw ref 19 with rubberized O ring O Fuel Chamber 3 eee attached not illustrated above are used TAL BOS OOO Oe Es Z M3 Pulse Chamber strainer Cover CONSTRUCTION DATA The HL series carburetor is a lightweight aluminum die cast carburetor composed of four basic parts metering body main diaphragm cover plate fuel pump body and strainer cover The diaphragm carburetor incorporates many of the same type components found in float type carburetors choke throttle idle and main mixture adjustment screws idle speed screw and inlet needle and seat Two styles of main and idle adjustment screws are available O ring type and spring loaded packing type Both types are designed to perform the dual purpose of sealing the metering chamber and providing adjustment screw friction A special insert housed in a brass cage forms a seat for the inlet needle An inlet tension spring exerts a pre determined force on the inlet control lever which holds the needle on its seat A metering diaphragm is subjected to engine suction on the metering chamber side and atmospheric pressure on the vented side Atmospheric pressure on the vented side pushes the diaphragm toward the inlet control lever opening the inlet needle to allow fuel to enter the metering chamber from which
13. the carburetor SERVICE HINTS When reassembling the inlet control lever and spring care should be taken to see that the spring rests in the well of the metering body and locates on the dimple of the inlet control lever as illustrated below CAUTION Do not stretch spring Inlet control lever is properly set when flush with floor of diaphragm cham ber INLET CONTROL LEVER SET METERING CHAMBER FLUSH WITH CHAMBER FLOOR MAIN ADJ USTMENT SCREW IDLE ADJUSTMENT SCREW Be certain main diaphragm gasket and cover casting are carefully fitted over the three small pins cast in rim at bottom of metering body also the fuel pump gasket diaphragm and fuel pump body over similar pins at bottom rim of main diaphragm cover casting Evenly tighten fuel pump body retaining screws to insure complete seal of casting separations at both diaph ragms Frequent cleaning or replacemnet of fuel strainer screen will aid satisfactory operation of the carburetor CAUTION clogged idle fuel supply channel and discharge Under extreme conditions of ports it may be necessary to remove the channel welch plug If so it must be very carefully done in following manner l Drill a 4 diameter hole through the diameter welch plug This hole should just break through the welch plug Deeper drill ing will seriously damage the body casting and its discharge ports located close behind the welch plug On some models an addition al smaller 4
Download Pdf Manuals
Related Search