FUEL SYSTEM. Section 3A Pulse Crankcase Driven Fuel Pump. Model 200/225 DFI. 1. Fuel Pressure/Vacuum Gauge (0-15 psi) (Obtain Locally)

Transcription

1 FUEL SYSTEM Section 3A Pulse Crnkcse Driven Fuel Pump Tle of Contents Specifictions A-1 Specil Tools A-1 Fuel Pump A-2 Fuel Pump Description/Opertion A-3 Checking for Restricted Fuel Flow Cused y Anti-siphon Vlves A-4 Checking Fuel Pump Lift (Vcuum) A-4 Vcuum Test Trouleshooting A-5 Specifictions Testing Fuel Pump A-5 Fuel Pump Removl/Disssemly A-6 Clening/Inspection A-7 Ressemly/lnstlltion A-7 3 A FUEL SYSTEM Fuel Pressure Crnkcse WOT Model 200/225 DFI Norml 2-3 psi ( kp) Minimum 1 psi (6.8 kp) Norml 8-10 psi ( kp) Mximum 10 psi (68.5 kp) Minimum 4 psi (27.4 kp) Specil Tools NOTE: Electric fuel pump pressure, if used in conjunction with engine mechnicl fuel pump, must e limited to no more thn 4 psi (27.4 kp). 1. Fuel Pressure/Vcuum Guge (0-15 psi) (Otin Loclly) R1 DECEMBER 2000 Pge 3A-1

2 Fuel Pump TORQUE REF. NO. QTY. DESCRIPTION l-in l-ft Nm. 1 ASSEMBLY DIAPHRAGM KIT 3 2 DISC CHECK VALVE 4 2 RETAINER 5 1 SPRING 6 1 CAP 7 1 SPRING 8 1 CAP 9 1 DIAPHRAGM 10 1 GASKET oost 11 1 GASKET pulse 12 1 GASKET 13 1 PLATE 14 1 FITTING 15 2 SCREW fuel pump (M5 x 40) SCREW pump to crnkcse (M6 x 50) BASE 18 1 FUEL HOSE CLIP 19 1 WASHER Pge 3A R1 DECEMBER 2000

3 Fuel Pump Description/Opertion The fuel pump is crnkcse-pressure-operted, diphrgm-type pump. Crnkcse pulsting pressure (creted y the up-nd-down movement of piston) is trnsferred to fuel pump y wy of pssge (hole) etween crnkcse nd fuel pump. When piston is in n upwrd motion, vcuum is creted in the crnkcse, thus pulling in on the fuel pump diphrgm. The inlet check vlve (in fuel pump) is opened nd fuel (from fuel tnk) is drwn into fuel pump. Downwrd motion of the piston forces the mixture out of the crnkcse into the cylinder. This motion lso forces out on the fuel pump diphrgm, which, in turn, closes the inlet check vlve (to keep fuel from returning to fuel tnk) nd opens the outlet check vlve, thus forcing fuel to the VST. Checking for Restricted Fuel Flow Cused y Anti-Siphon Vlves While nti-siphon vlves my e helpful from sfety stnd-point, they clog with deris, they my e too smll, or they my hve too hevy spring. Summrizing, the pressure drop cross these vlves cn, nd often does, crete opertionl prolems nd/or power-hed dmge y restricting fuel to the fuel pump nd VST. Some symptoms of restricted (len) fuel flow, which could e cused y use of n nti-siphon vlve, re: 1 - Loss of fuel pump pressure 2 - Loss of power 3 - High speed surging 4 - Preignition/detontion (piston dome erosion) 5 - Outord cuts out or hesittes upon ccelertion 6 - Outord runs rough 7 - Outord quits nd cnnot e restrted 8 - Outord will not strt 9 - Vpor lock Since ny type of nti-siphon device must e locted etween the outord fuel inlet nd fuel tnk outlet, simple method of checking [if such device (or d fuel) is prolem source] is to operte the outord with seprte fuel supply which is known to e good, such s remote fuel tnk. If, fter using seprte fuel supply, it is found tht the nti-siphon vlve is the cuse of the prolem, there re 2 solutions to the prolem; either 1) replce the nti-siphon vlve with one tht hs lighter spring tension or 2) replce it with solenoid-operted fuel shut off vlve R1 DECEMBER 2000 Pge 3A-3

4 Checking Fuel Pump Lift (Vcuum) The squre fuel pump is designed to lift fuel (verticlly) out 60 in. (1524 mm) if there re no other restrictions in the system using fuel hose tht is 5/16 in. (7.9 mm) minimum dimeter. As restrictions re dded, such s filters, fittings, vlves etc., the mount of fuel pump lift decreses. Fuel pump vcuum nd ir ules in the fuel supply cn e checked with vcuum guge, t-fitting nd cler piece of fuel hose. Connect the cler hose etween the inlet fitting on the pulse driven fuel pump nd the vcuum guge t-fitting keeping the t-fitting s close s possile to the pump. Connect the fuel line from the fuel tnk to the remining connection on the t-fitting. c Cler Hose -T-fitting c -Vcuum Guge Vcuum Test Trouleshooting This test is normlly performed t n idle speed. As engine rpm increses, there will e slight increse in vcuum. The increse should not exceed specifiction Norml Reding Below 2.5 in. of mercury Reding ove 2.5 in. of mercury Restriction within the fuel system Restricted nti-siphon vlve Restriction within the primer ul Kinked or collpsed fuel hose Plugged wter seprting fuel filter (in the ot) Restriction in fuel line thru-hull fitting Restriction in fuel tnk switching vlves Plugged fuel tnk pick-up screen Pge 3A R1 DECEMBER 2000

5 Testing Fuel Pump Instll cler fuel hose(s) etween fuel pump nd VST. Run engine, nd inspect fuel pssing thru hose(s) for ir ules. Prolem: Air Bules in Fuel Line Low fuel in tnk. Fill tnk with fuel. Loose fuel line connection. Check nd tighten ll connectors. Fuel pump fitting loose. Tighten fitting. A hole or cut in fuel line. Check condition of ll fuel lines nd replce. Fuel Pump nchor screw(s) loose. Tighten ll screws evenly nd securely. Fuel Pump filter cover nchor screw loose. Tighten screws securely. Fuel pump filter gsket worn out. Replce gsket. Fuel pump gsket(s) worn out. Reuild fuel pump. Fuel vporizing Fuel with high reed vpor pressure (winter grde fuel) my vporize (form ules) when used in hot/wrm wether. Use fuel with lower reed vpor pressure (summer grde fuel). Prolem: Lck of Fuel Pump Pressure An nti-siphon vlve. See Checking for Restricted Fuel Flow preceding. Air in fuel line. See Air Bules in Fuel Line, ove. A dirty or clogged fuel filter. Clen or replce fuel filter. The fuel pickup in fuel tnk is clogged or dirty. Clen or replce pickup. Worn out fuel pump diphrgm. Reuild fuel pump. Worn out check vlve(s) in fuel pump. Reuild fuel pump. A leky check vlve gsket. Reuild fuel pump. Pulse hole(s) plugged. Remove fuel pump nd clen out holes. Hole in pulse hose. Replce pulse hose. Loose pulse hose. Tighten connection(s). Fuel hose internl dimeter too smll. Use 5/16 I.D. fuel hose. Primer ul check vlve not opening. Replce primer ul. Excessive fuel lift required. Fuel lift exceeds 2.5 in. of vcuum (mercury) R1 DECEMBER 2000 Pge 3A-5

6 Fuel Pump Removl/Disssemly IMPORTANT: Fuel pump diphrgm nd gskets should not e re-used once fuel pump is disssemled. NOTE: Externl low pressure electric fuel pump nd vpor seprtor hve een removed from illustrtion to provide improved visul clrity for loction of mechnicl fuel pump. 1. c d e -Disconnect fuel hose from tnk to fuel pump -Disconnect fuel hose from fuel pump to wter seprtor c -Disconnect pulse hose d-remove mounting screws e -Remove fuel pump Disssemle fuel pump. Reverse View of Pump Body Pge 3A R1 DECEMBER 2000

7 Clening/Inspection 1. Clen fuel pump housing, check vlves, pulse chmer nd pump se in solvent nd dry ll ut check vlves with compressed ir. 2. Inspect ech check vlve for splits, chips nd for proper seling ginst pump housing. 3. Inspect oost springs for wekness or rekge. 4. Inspect fuel pump housing, pulse chmer nd se for crcks or rough gsket surfce nd replce if ny re found. 5. Inspect fitting on fuel pump housing for loosening or ny signs of fuel or ir leks. Replce or tighten fitting if lek is found. Ressemly/lnstlltion ASSEMBLY NOTE: The new repir kits contin check vlves mde of plstic mteril, impervious to dmge from dditives. When repiring the fuel pump discrd old ruer nd smll plstic check vlve disks, nd instll one new plstic disk under ech retiner. Cution must e tken not to push the check vlve retiner to tightly ginst the check vlve, this my cuse vlve to deform. CORRECT -Check Vlve Retiner -Check Vlve (Plstic) INCORRECT Insert Retiner through check vlve -Plstic Check Vlve R1 DECEMBER 2000 Pge 3A-7

8 2. Instll check vlves nd retiners into fuel pump ody. 3. With retiner instlled in pump ody, rek retiner rod from retiner y ending sidewys. -Rod -Retiner Cp Reinstll rod into retiner cp nd, use smll hmmer or hmmer nd punch to tp rod down into retiner until flush with top of retiner. -Rod -Retiner Cp Pge 3A R1 DECEMBER 2000

9 5. Plce oost spring into pump ody nd plce cp onto oost spring. c -Boost Spring -Pump Body c -Cp Assemle reminder of components s shown nd instll retining screws thru to lign. Reverse View of Pump Body Instll pump onto engine. Torque to 55 I. in. (6 N m). 8. Instll hoses onto proper fittings nd secure with st-strps. 9. Run engine nd check for leks R1 DECEMBER 2000 Pge 3A-9