85 engine electrical.pdf - Vintage Snow

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ENGINE ELECTRICALEFI Fuel System Maintenance and TestingTank, Hose And FiltersThe fuel tank is the reservoir for the fuel. It contains aflexible hose with a weighted pickup and a coursescreen which drops to the lowest part of the tankregardless of machine attitude. Fuel trav~ls throughthe urethane fuel hose to the primary 75 micron filterlocated under the airbox and then to the fuel pump.From the pump the fuel hose changes to a reinforcedrubber hose which carries fuel to the secondary 10micron filter located under the throttle bodies, andthen to the fuel rail.STANDARD FUEL HOSEREINFORCEDPRIMARY FILTERThe fuel tank, hoses and filters require little, if any, service. Periodically inspect tank and hose condition. Assurethat the pickup is clean and properly positioned and vent tube is properly routed and not kinked or pinched.Replace any hose showing signs of deterioration. Replace primary and secondary filters at 5000 mile (8000 km)intervals, every two years, or more often if contamination of any kind is present in the system. Use OEM parts only.If for any reason, at any engine RPM, the fuel system should fail to deliver a sufficient quantity of fuel to meetengine requirements and have some fuel returning to the tank, the fuel hoses must be checked for obstructionsand/or the fuel filters replaced. If the problem does not rectify itself, proceed to fuel pump testing.JCAUTION: Whenever inspection reveals worn, damaged or defective parts, replacement is necessary in order toavoid serious damage to the machine or injury to the operator.Fuel PumpThe electric fuel pump is located on the bulkheadunderneath the mag end throttle bore. The 12v pumpreceives fuel from the fuel tank, then sends it throughthe small strainer in the pump inlet nozzle, through theroller vane type pump, through the outlet check valveand on to the injector rail. The pump is completelyfilled with fuel during operation. This provides cooling,corrosion protection and lubrication.CAUTION: Never run the pump without a sufficientsupply of fuel or pump damage will result. The pumpis cooled and lubricated by fuel.OutlettArmaturePumpStrainerThe pump outlet pressure can reach as much as 70 psi. It is regulated however to 35 to 37 psi by the fuel railpressure regulator. Located near the outlet end of the pump is a check valve. The pressure regulator also acts asa check valve. There will be high pressure fuel between these two valves.The fuel pump is a sealed unit. No internal repair of the pump components can be performed. Pump condition canbe verified by an amp draw test, an output volume test and an output pressure test.Amp Draw Test: Install a DC ammeter in series with the purple pump power feed wire. The draw should be 2.5amps. A draw at or slightly less than that value indicates the pump is electrically sound. No draw indicates eitherno power present or an open circuit in either the pump or its ground. A draw greater than that value indicates eithera stuck or defective pump. A pump which is stuck due to long periods of non-use can occasionally be freed bystriking with a soft face hammer. If this does not free the pump, it must be replaced.Output Volume Test: The output volume of the fuel pump and delivery system can be verified with an outputvolume test. To perform test, start machine and make sure delivery side of system is filled and pressurized to thepressure regulator. With machine turned off, disconnect fuel return hose and place it into a 200 milliliter graduatedcontainer. Activate ECU to cycle pump for approximately five seconds. The measured output during this timeperiod should not be less than 90 to 100 milliliters. NOTE: Battery voltage less than 12.6vDC or restrictions in thefu el lines or filters will cause output to be less than recommended amount.8/94 4.44
cOutput Pressure Test: Install EFI fuel Systempressure tester (PN 2870982) in fuel line on PTa endof rail. NOTE: Use caution when removing hose. Therail may contain pressurized gas if engine has beenrecently run. Activate dealer mode using selectmonitor service harness plug, by connecting gray andblack test loads together or by jumping gray and blackwire terminals at diagnostic plug, then turning onignition switch. With pump running, system pressureshould be between 35 and 37 psi. A pressure readingof higher than normal indicates a faulty pressureregulator or an obstructed fuel return hose. Apressure reading lower than normal indicates a faultypressure regulator, a bad pump, or a restriction in fuelhoses or filters between tank and rail. If pressurestarts out normal and then gradually lowers, suspectthe fuel tank vent and/or any of the fuel filters or hoseswhich may restrict fuel delivery to the pump.Fuel pressure can also be checked with the gauge inplace and with the engine running. Pressure shouldbe checked at both idle and at operating RPM. Aplugged filter may show good pressure at idle butrestrict flow at operating RPM.Fuel RailThe fuel rail is the fuel distribution manifold for theinjectors. The injectors slip into fittings on theunderside of the rail which are sealed with a-Ringsaround the injectors. The rail stores fuel underpressure so that simply opening the injectors will allowfuel to pass from the fuel rail through the injectors andinto the throttle body. Pressure in the fuel rail iscontrolled by the pressure regulator.The fuel rail requires little if any service. Periodicallyinspect seal between rail and injectors and rail andregulator. If any leakage exists, replace a-Rings andrecheck for leaks.Return HoseThe return hose runs between the bottom of thepressure regulator and the top of the fuel tank. Itprovides a path for excess fuel from the fuel rail toreturn to the fuel tank. If this hose should becomeobstructed in any way, the excessive fuel pressure inthe rail will cause a rich operating condition.Pressure RegulatorThe fuel pressure regulator is mounted on theopposite end of the fuel rail from where the fuel enters.Its function is to maintain a consistent fuel pressurewithin the rail by allowing pressure above the desiredlevel to bleed off the rail, through the regulator, andback to the tank by way of the return hose. When thefuel pressure on the bottom of the regulatordiaphragm reaches between 35 and 37 psi, itovercomes the spring on the other side of thediaphragm and pushes it up. This opens the valve tothe return hose, allowing fuel to escape andmaintaining a specific pressure.4.45ENGINE ELECTRICALFuel System Maintenance and Testing8/94
Page 1 and 2: CHAPTER 4ENGINE ELECTRICAL "Ignitio
Page 3 and 4: Electronic Control SystemSystem III
Page 5 and 6: 1985 ModelsENGINE ELECTRICALIgnitio
Page 8 and 9: ENGINE ELECTRICALIgnition Data1988
Page 16 and 17: ENGINE ELECTRICALTypical 1985 - Cur
Page 18 and 19: ENGINE ELECTRICALSingle Cylinder CO
Page 20 and 21: ENGINE ELECTRICALTwin Cylinder Fan
Page 22 and 23: ENGINE ELECTRICALThree Cylinder COl
Page 24 and 25: ENGINE ELECTRICALOperating RPM Timi
Page 26 and 27: ENGINE ELECTRICALIgnition I Chargin
Page 28 and 29: ENGINE ELECTRICALIgnition I Chargin
Page 30 and 31: ENGINE ELECTRICALIgnition System Tr
Page 32 and 33: ENGINE ELECTRICALTypical Exciter, P
Page 34 and 35: ENGINE ELECTRICALBattery ServiceLoa
Page 36 and 37: ENGINE ELECTRICALElectric Starter S
Page 39: Electrical Fuel InjectionSection 44
Page 42 and 43: ENGINE ELECTRICALElectronic Fuel In
Page 44 and 45: ENGINE ELECTRICALPower Up Testing -
Page 46 and 47: ENGINE ELECTRICALPower Up Testing -
Page 48 and 49: ENGINE ELECTRICALAlternator Control
Page 52 and 53: ENGINE ELECTRICALEFI Fuel System Ma
Page 54 and 55: ENGINE ELECTRICALEFI Fuel System Te
Page 56 and 57: ENGINE ELECTRICALSystem III - Elect
Page 62 and 63: ENGINE ELECTRICALSystem 111- Electr
Page 64 and 65: ENGINE ELECTRICALSystem 111- Electr
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Page 68 and 69: ENGINE ELECTRICALEFI ElectronicsThe
Page 70 and 71: ~(J)~OR/6lKSTATOR RESISTANCES 1'10%

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