Page 1: Table Of Contents
DIRECT FUEL INJECTION FUEL SYSTEM Section 3B – Direct Fuel Injection Table of Contents Specifications ......3B-2 Throttle Plate Assembly Removal .
Page 2: Specifications
DIRECT FUEL INJECTION Specifications Fuel System Specifications Fuel Pressure 2 psi (613.5 13.8 kPa) Air Pressure 2 psi (544.0 13.8 kPa) Fuel/Air Differential 10 psi (68.5 kPa) High Pressure Electric Fuel Pump Amperage 6-9 Amps Draw Low Pressure Electric Fuel Pump Amperage 1-2 Amps Draw Low Pressure Electric Fuel Pump Output...
Page 3: Special Tools
DIRECT FUEL INJECTION Special Tools 1. Duel Fuel/Air Pressure Gauge 160 psi – 91-852087A1/A2/A3 57818 Schrader Valve “Tee” (22-849606) 2. Adaptors to convert pressure gauge 91-852087A1/A2 to an A23 NOTE: 2 Adaptors 91-803804A2 are required to convert a pressure gauge set. 1/2 in.
Page 4 DIRECT FUEL INJECTION 7. DMT 2000 Digital Tachometer Multi-meter P/N 91-854009A1 8. Clamp Tool Kit 91-803146A2 57316 Clamp Tool 91-803146T 9. Gearcase Leakage Tester (FT-8950) 57714 Page 3B-4 90-888438 JUNE 2002...
Page 5: Notes
DIRECT FUEL INJECTION Notes: 90-888438 JUNE 2002 Page 3B-5...
Page 6: Air Handler
DIRECT FUEL INJECTION Air Handler Liquid Neoprene Page 3B-6 90-888438 JUNE 2002...
Page 7 DIRECT FUEL INJECTION Air Handler TORQUE REF. QTY. DESCRIPTION lb-in lb-ft AIR HANDLER ASSEMBLY VAPOR SEPARATOR ASSEMBLY CLAMP (18.3) HOSE (22 IN. Bulk) FUEL PUMP ASSEMBLY FILTER-Fuel Pump SCREW (M6 x 35) 11.3 BRACKET-Fuel Pump Mount CLAMP (18.3) HOSE INSULATING SLEEVE ELBOW O RING FUEL PUMP ASSEMBLY...
Page 8: Air Handler Components
DIRECT FUEL INJECTION Air Handler Components Page 3B-8 90-888438 JUNE 2002...
Page 9: Air Handler Components
DIRECT FUEL INJECTION Air Handler Components TORQUE REF. QTY. DESCRIPTION lb-in lb-ft – AIR HANDLER ADAPTOR PLATE GASKET REED BLOCK SCREW (M6 x 1) 10.2 BUSHING GROMMET WASHER SCREW (M8 x 30) AIR PLENUM KIT GASKET SCREW (M4 x 16) SENSOR–MAP BRACKET TEMPERATURE SENSOR...
Page 10 DIRECT FUEL INJECTION Air Handler Components Page 3B-10 90-888438 JUNE 2002...
Page 11 Air Handler Components TORQUE REF. QTY. DESCRIPTION lb-in lb-ft SEAL GROMMET CLIP SCREW (#10-16 X .750) CLAMP SCREW (M6 X 25) 10.2 WASHER DECAL-Logo (M2 Jet Drive) DECAL-Logo (3.0l V6) DECAL-Logo (Mercury Optimax 250) DECAL-EPA Label Info 90-888438 JUNE 2002 Page 3B-11...
Page 12: Vapor Separator Components
DIRECT FUEL INJECTION Vapor Separator Components Page 3B-12 90-888438 JUNE 2002...
Page 13 DIRECT FUEL INJECTION Vapor Separator Components TORQUE REF. QTY. DESCRIPTION lb. in. lb. ft. N·m COVER KIT FITTING-Straight FITTING-Elbow SEAL FITTING KIT-Pump Outlet O RING SCREW (#8-32 x .750) GASKET FLOAT KIT SHAFT-Float NEEDLE VALVE SCREW (#6-32 x .187) FUEL PUMP ASSEMBLY SLEEVE BOWL KIT SEAL...
Page 14: Fuel Rails
DIRECT FUEL INJECTION Fuel Rails Page 3B-14 90-888438 JUNE 2002...
Page 15 DIRECT FUEL INJECTION Fuel Rails TORQUE REF. QTY. DESCRIPTION lb-in lb-ft AIR INJECTOR KIT WASHER ASSEMBLY-Cupped FUEL RAIL (PORT) FUEL RAIL (STARBOARD) FITTING O-RING KIT CLAMP SCREW (M5 x 8) FUEL VALVE KIT O-RING KIT SCREW (M5 x 16) COVER SPRING O-RING DIAPHRAGM...
Page 16: Air Compressor Components
DIRECT FUEL INJECTION Air Compressor Components Loctite 271 Page 3B-16 90-888438 JUNE 2002...
Page 17 DIRECT FUEL INJECTION Air Compressor Components TORQUE REF. QTY. DESCRIPTION lb-in lb-ft AIR COMPRESSOR END CAP RING-Retaining SCREW (M6 X 20) 11.3 O RING O RING CONNECTING ROD PISTON ASSEMBLY LOCK RING REED PLATE ASSEMBLY O RING O RING SEAL COMPRESSOR HEAD KIT FITTING 33.9...
Page 18: Dfi Operation
DIRECT FUEL INJECTION DFI Operation Air Induction Through Crankcase Once inside the enclosure the air enters the plenum through the throttle shutter which is located in the plenum assembly. The air then continues through the reed valves and into the crankcase. The throttle shutter is actuated by the throttle shaft. Mounted on a separate shaft is a throttle position sensor (TPS).
Page 19: Oil
DIRECT FUEL INJECTION To equalize the pulses developed by the pumps (both air and fuel) a tracker diaphragm is installed in the starboard rail. The tracker diaphragm is positioned between the fuel and air passages. The tracker diaphragm is a rubber diaphragm which expands and retracts depending upon which side of the diaphragm senses the pressure increase (pulse).
Page 20: Testing Electric Fuel Pump Pressure Output 3B-20
DIRECT FUEL INJECTION Testing Electric Fuel Pump Pressure Output Low Pressure Electric Fuel Pump IMPORTANT: After completing fuel pressure tests, reconnect and secure fuel outlet hose to fuel pump with full circle stainless clamps in Clamp Tool Kit 91-803146A1. 1. Remove outlet fuel hose from low pressure pump. Install a short piece of hose (obtain locally) onto pump outlet fitting.
Page 21: High Pressure Electric Fuel Pump
DIRECT FUEL INJECTION High Pressure Electric Fuel Pump 1. Install Pressure Gauge Assembly (91-852087A1/A2/A3) to starboard fuel rail pres- sure test valve. NOTE: If low air or low fuel pressure is indicated, swap hoses between air and fuel test ports. If low reading moves, gauge accuracy should be checked. NOTE: After 15 seconds of cranking engine with starter motor, fuel pressure gauge should indicate 90 2 psi (620.5...
Page 22: Fuel Management Assembly Removal
DIRECT FUEL INJECTION Fuel Management Assembly Removal CAUTION Fuel system must be bled off prior to removal of fuel system components. WARNING Drain fuel from vapor separator tank (VST) into a suitable container. Even though VST has been drained, fuel may still remain in fuel rails and hoses. Normal pre- cautionary procedures should be adhered to while working with the fuel system.
Page 23 DIRECT FUEL INJECTION NOTE: Lower fuel hose is excess fuel return from fuel rails. Upper fuel hose is fuel inlet from electric circulating pump beside fuel/water separator. 7. Remove vapor separator vent hose. 8. Remove the fuel outlet hose and fuel return hose from fuel rails. 9.
Page 24 DIRECT FUEL INJECTION 11. Disconnect throttle cam link rod and the Throttle Position Sensor link rod. 12. Disconnect MAP sensor and temperature sensor from air management assembly. Throttle Cam Link Rod Throttle Position Sensor Link Rod MAP Sensor Temperature Sensor 13.
Page 25: Reed Block Assembly Removal
DIRECT FUEL INJECTION Reed Block Assembly Removal 1. Remove 12 screws securing air plenum to crankcase cover. Screws (12 each) M6x40 Reed Block Assembly Installation 1. Secure oil pump to air plenum with 3 bolts. Torque bolts to 140 lb. in. (16 Nm). 2.
Page 26: Air Temperature Sensor Removal
DIRECT FUEL INJECTION Air Temperature Sensor Removal Disconnect sensor harness and unscrew sensor. 57793 Air Temperature Sensor Harness Connector Air Temperature Sensor Air Temperature Sensor Installation Screw sensor into air plenum. Reconnect sensor harness. Throttle Plate Assembly Removal NOTE: The throttle plate assembly is calibrated and preset for proper running character- istics and emissions at the factory.
Page 27: Vapor Separator Disassembly
DIRECT FUEL INJECTION Vapor Separator Disassembly 1. Remove 7 screws securing separator cover and remove cover. 2. Inspect seal in fuel pump chamber of separator tank for cuts and abraisions. Replace seal if necessary. If seal is serviceable, apply 2-4-C with Teflon to seal lips. 57955 57342 Screws (7 each)
Page 28 DIRECT FUEL INJECTION 6. Loosen screw securing float assembly and remove float. Inspect float for deterioration or fuel retention. Replace float as required. 7. Remove phenolic sealing plate and inspect imbedded neoprene seal on both sides of plate for cuts or abraisions. Replace plate/seal assembly as required. 56059 56058 Screw...
Page 29: Vapor Separator Reassembly
DIRECT FUEL INJECTION Vapor Separator Reassembly 1. Reinstall phenolic sealing plate onto vapor separator cover. 2. Secure float, needle and pivot pin assembly to separator cover with screw. Torque screw to 10 lb. in. (1.0 Nm). 3. Apply 2-4-C with Teflon to lips of seal in separator cover. 4.
Page 30: Air Plenum Installation
DIRECT FUEL INJECTION Air Plenum Installation Secure plenum to crankcase with 12 bolts. Torque bolts to 100 lb. in. (11.5 Nm). in se- quence shown. 57915 Air Plenum Bolts [Torque to 100 lb. in. (11.5 Nm)] Low Pressure Electric Fuel Pump Installation NOTE: If pump does not have a sleeve or grommet, refer to Service Bulletin 98-8.
Page 31 DIRECT FUEL INJECTION 2. Secure bracket assembly to vapor separator with 2 screws. Torque screws to 100 lb. in. (11.5 Nm). 57964 Screws – Torque to 100 lb. in. (11.5 Nm) Sta-strap securing pump to bracket Ground lead – attach to air plenum IMPORTANT: Only use tool 91-803146T (or Snap-On equivalent YA3080) to crimp full circle clamps.
Page 32 DIRECT FUEL INJECTION 4. Connect fuel hose from top of low pressure fuel pump to 90 elbow on back side of vapor separator. Secure hose with 18.3 mm full circle clamp (54-880141) using crimp- ing tool 91-803146T. 57966 Secure Fuel Hose with 18.3 mm Full Circle Clamp (54-880141) Page 3B-32 90-888438 JUNE 2002...
Page 33: Vapor Separator Installation
DIRECT FUEL INJECTION Vapor Separator Installation 1. Secure vapor separator to air plenum with 3 bolts. Torque bolts to 140 lb. in. (16.0 Nm). 2. Connect fuel inlet hose to fuel lift pump. 3. Connect vent hose to vapor separator. 4.
Page 34 DIRECT FUEL INJECTION 7. If fuel hoses were removed, secure hoses with proper full circle clamp using tool 91-803146T (or Snap-On equivalent YA3080) to crimp clamps. Use stainless screw clamp on vapor separator vent hose and inlet fuel hose to fuel lift pump. 59409 59415 Full Circle Clamp...
Page 35: Fuel Rail Removal
DIRECT FUEL INJECTION Fuel Rail Removal NOTE: To provide improved access to the fuel rails, it is recommended that the expansion chamber be removed as follows: 1. Remove coolant hose between air compressor and expansion chamber, and rail and expansion chamber. 2.
Page 36 DIRECT FUEL INJECTION 3. Remove fuel, water and air hoses from fuel rail. 00136 00137 Port Top Fuel Rail Connections Starboard Top Fuel Rail Connections Water Inlet Hose to Compressor Air Hose Retainer Retainer Allen Screws (remove) Allen Screws (remove) 00139 00138 Port Bottom Fuel Rail Connections...
Page 37 DIRECT FUEL INJECTION 5. As fuel rail is removed, use a flat tip screw driver to hold direct injectors in cylinder head. 56121 Fuel Rail Direct Injectors The starboard fuel rail contains 3 fuel injectors and a tracker valve. http://motorka.org The port fuel rail contains 3 fuel injectors, 1 fuel regulator, and 1 air regulator.
Page 38 DIRECT FUEL INJECTION FUEL INJECTOR REMOVAL 1. Remove 2 screws securing injector. NOTE: Use a cotter pin extractor tool in pry holes to remove injectors. 2. Gently pry up on injector to loosen o-ring adhesion and remove injector. 57967 57970 Screws Pry Holes 3.
Page 39 DIRECT FUEL INJECTION FUEL INJECTOR INSTALLATION NOTE: Apply anti-seize grease (obtain locally) or 2-4-C with Teflon to fuel injector attach- ing screw threads. 1. Insert fuel injector into fuel rail with connector pins facing (inwards) towards center of engine. NOTE: Turn injector back-and-forth slightly to seat injector o-rings in fuel rail while secur- ing injector with retainer and 2 screws.
Page 40: Fuel Pressure Regulator
DIRECT FUEL INJECTION Fuel Pressure Regulator The fuel regulator is located on the port fuel rail. 57980 The fuel pump is capable of delivering more fuel than the engine can consume. Excess fuel flows through the fuel pressure regulator, interconnecting passages/hoses, fuel cool- er, and back to the vapor separator tank.
Page 41 DIRECT FUEL INJECTION Regulator Closed Regulator Open Ç Ç Ç Ç Ç Ç Ç Ç Top Cover Air Rail Expansion Plug Air Passage (from Air Compressor) O-ring 10 - Fuel Return Passage (to Vapor Separator) Spring Retainer 11 - Fuel Inlet Passage (from Electric Fuel Pump) Spring 12 - Diaphragm Assembly...
Page 42 DIRECT FUEL INJECTION FUEL REGULATOR REMOVAL 1. Remove 4 screws securing regulator and remove regulator. 2. Inspect regulator diaphragm for cuts or tears. 3. Inspect regulator housing o-ring for cuts and abraisions. Replace components as re- quired. 57968 57969 Screws Spring Fuel Regulator Diaphragm...
Page 43: Air Pressure Regulator
DIRECT FUEL INJECTION Air Pressure Regulator The air pressure regulator is located on the port fuel rail. 57980 The air pressure regulator is designed to limit the air pressure inside the rails to approxi- mately 80 psi. The air regulator uses a spring (pressure) to control the air pressure. This spring (80 psi) holds the diaphragm against the diaphragm seat.
Page 44 DIRECT FUEL INJECTION Regulator Closed Regulator Open Ç Ç Ç Ç Ç Ç Ç Ç Ç Ç Ç Ç Ç Ç Top Cover Air Rail Expansion Plug Air Passage (from Air Compressor) Spring Retainer Excess Air Passage (to Exhaust Adaptor) Vent 10 - Fuel Inlet Passage (from Electric Fuel Pump)
Page 45 DIRECT FUEL INJECTION AIR REGULATOR REMOVAL 1. Remove 4 screws securing regulator and remove regulator. 2. Inspect regulator diaphragm for cuts or tears. Replace as required. 57968 57974 Screws Spring Air Regulator Diaphragm AIR REGULATOR INSTALLATION NOTE: Apply a light coat of 2-4-C with Teflon to diaphragm surface to aid in the retention of diaphragm on fuel rail during reassembly.
Page 46: Tracker Valve
DIRECT FUEL INJECTION Tracker Valve The tracker valve is located on the starboard fuel/air rail assembly. 57979 The DFI system must maintain a constant 10 psi pressure difference between the fuel pressure and air pressure in the rails, at all times. The tracker is designed to maintain the 10 psi differential when the air or fuel pressure suddenly raises (i.e.
Page 47 DIRECT FUEL INJECTION Engine Off (No Pressure) Engine at Operating Pressures Top Cover Air Rail Spring Retainer (not shown) Air Passage (from Air Compressor) Spring Fuel Inlet Passage (from Electric Fuel Pump) O-ring Diaphragm Assembly Diaphragm (at rest) Seat 90-888438 JUNE 2002 Page 3B-47...
Page 48 DIRECT FUEL INJECTION TRACKER VALVE REMOVAL 1. Remove 4 screws securing tracker valve and remove tracker assembly. 2. Inspect tracker diaphragm for cuts and tears. 3. Inspect tracker cover o-ring for cuts and abraisions. Replace components as re- quired. 57802 58009 Screws Diaphragm...
Page 49: Fuel Rail Cleaning
DIRECT FUEL INJECTION Fuel Rail Cleaning After all fuel injectors, air regulator, tracker valve, fuel regulator, inlet hoses and outlet hoses have been removed, the fuel rails may be flushed out with a suitable parts cleaning solvent. Use compressed air to remove any remaining solvent. Direct Injector Removal 1.
Page 50: Direct Injector Leak Test
DIRECT FUEL INJECTION 6. An ohm test of the direct injector may be made by connecting test leads to injector terminals. Ohm reading should be 1.3 0.3 ohm. 7. An ohm test to determine if direct injector windings are shorted to ground can be made by connecting one ohm lead to either injector pin while touching the other ohm lead to the injector metal case.
Page 51: Fuel Rail And Direct Injector Installation
DIRECT FUEL INJECTION NOTE: If cylinder head is going to be replaced, remove cup washers from each direct in- jector port by prying out with a flat tip screwdriver. Reinstall washers with retainers into new cylinder head. Washers provide tension between direct injectors, cylinder head and fuel rails.
Page 52: Air Compressor
DIRECT FUEL INJECTION Air Compressor Air compressor is a single cylinder, water cooled and lubricated by the outboard oil pump. Air Compressor Specifications Air Compressor Type Reciprocating Piston (1 to 1 ratio with engine RPM) Compressor Output @ Idle – 80 psi @ W.O.T.
Page 53 DIRECT FUEL INJECTION COMPRESSOR REMOVAL 1. Disconnect battery cables from battery terminals. 2. Remove flywheel cover. 3. Use 3/8 inch (9.5 mm) drive on belt tensioner arm to relieve belt tension. Remove belt. 57806 Belt Tensioner 3/8 in. (9.5 mm) drive 90-888438 JUNE 2002 Page 3B-53...
Page 54 DIRECT FUEL INJECTION CAUTION If engine has been recently run, air pressure outlet hose fittings may be extremely hot. Allow components to cool off before beginning disassembly. NOTE: Remove 2 screws securing retainer plate to remove air pressure outlet hose. In- spect o-rings on air pressure hose fitting for cuts or abraisions.
Page 55: Air Compressor Disassembly/Reassembly 3B-55
DIRECT FUEL INJECTION Air Compressor Disassembly/Reassembly IMPORTANT: If an internal failure of the air compressor has occurred, i.e. broken reed, scuffed piston, bearing failure, etc. – all air hoses, fuel rails and injectors should be disassembled and inspected for metal debris. Failure to remove all metal debris will result in poor performance and/or powerhead failure.
Page 56: Air Compressor End Cap/Crankshaft Removal And Reassembly
DIRECT FUEL INJECTION Air Compressor End Cap/Crankshaft Removal and Reassembly DISASSEMBLY 1. Remove flywheel cover. 2. Use 3/8-inch (9.5 mm) drive on belt tensioner arm to relieve belt tension, and remove belt. 3. Remove the 6 bolts that retain the pulley to the pulley flange. 57784 Pulley retaining bolts (6) Tensioner...
Page 57 DIRECT FUEL INJECTION 4. Remove the 4 bolts that retain the end cap to the compressor body. 57809 End cap retaining bolts (4) 5. While rotating the pulley flange alternately clockwise and counterclockwise about 1/8 to 1/4 turn, pull outward on the pulley flange. Continue rotating until the end cap as- sembly has been removed from the compressor body.
Page 58 DIRECT FUEL INJECTION REASSEMBLY 1. Lubricate end cap O-ring and O-ring contact area in compressor body with two cycle oil. 2. Slide the new end cap assembly into the compressor body, keeping the connecting rod journal lined up with the open end of the connecting rod, until the crankshaft just enters the open end of the connecting rod.
Page 59: Air Compressor Flow Diagram
DIRECT FUEL INJECTION Air Compressor Flow Diagram 00027 Air Filter Fuel Regulator [90 2 psi (620.5 13.8 kPa)] Compressor Air Inlet #4 Fuel Injector Air [80 2 psi (551.6 13.8 kPa)] Air Regulator [80 2 psi (551.6 13.8 kPa)] Fuel System Pressure Test Valve #2 Fuel Injector #1 Fuel Injector Rail Water to Expansion Chamber...
Page 60: Air Compressor Pressure Test
DIRECT FUEL INJECTION Air Compressor Pressure Test Install Pressure Gauge Assembly 91-852087A1/A2/A3 to fuel rail pressure test valves. Starboard rail has fuel pressure test valve. Port fuel rail has air pressure test valve. NOTE: After 15 seconds of cranking engine with starter motor, air pressure gauge should indicate 80 2 psi (551.6 13.8 kPa) and fuel pressure gauge should indicate 90 2 psi (620.5...
Page 61 DIRECT FUEL INJECTION FUEL PRESSURE AND AIR PRESSURE TROUBLESHOOTING CHART PROBLEM CORRECTIVE ACTION Fuel Pressure and Air Pressure are Both Low 1. Inspect air compressor air intake (air filter in fly- wheel cover) for blockage. 2. Remove air compressor cylinder head and in- spect for scuffing of cylinder wall.

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