CHEVROLET DIESEL FUEL SYSTEMS - UCoz

CHEVROLETDIESEL FUEL SYSTEMS1.8L2.2LO P ER A T IO N , D IA G N O S IS A N D R E P A IR M A N U A L

FOREWORDT h is su p p le m e n ta l m a n u a l is d e sig n ed to p ro v id e dealer service p e rso n n e l w ithin fo rm a tio n o n d ia g n o s in g , m a in ta in in g a n d servicing th e diesel fuel in je c tio nsystem s u sed in C h e v ro le t p assen g er cars a n d lig h t-d u ty tru c k s e q u ip p e d w ithdiesel engin es.W h e n re fe re n ce is m a d e to a sp ecific to o l, n u m b e r o r b r a n d n a m e , a n e q u iv a le n tp ro d u c t m a y be u se d in p lace o f th e re c o m m e n d e d item .A ll in f o r m a tio n , s p e c ific a tio n s a n d illu stra tio n s c o n ta in e d in th is m a n u a l areb a se d o n th e latest p r o d u c t in fo r m a tio n a t th e tim e o f p u b lic a tio n . T h e right isreserv ed to m a k e p ro d u c t o r p u b lic a tio n ch a n g es, a t a n y tim e , w ith o u t n o tic e.P o rtio n s o f th is m a n u a l w ere p ro d u c e d w ith th e aid o f S ta n a d y n e In c ., D ieselS ystem s G ro u p ; L u c a s CAV, a div isio n o f L u c as In d u strie s, In c .; a n d D iesel K ikiU .S .A . C o ., L td .

CONTENTSS E C T IO N 1 Diesel Fuel Familiarization. . 1-1SEC T IO N 2 Stanadyne Injection Pumps. . 2-1SE C T IO N 3 Lucas CAV Injection P u m p . 3-1SE C T IO N 4 Diesel Kiki Injection Pumps . . 4-1SEC T IO N 5 Fuel Lines and Nozzles. 5-1SEC T IO N 6 Glow Plug Systems. 6-1SECTIO N 7 Injection Pump Diagnosis. 7-1A-l

SECTION 1DIESEL FUEL FAMILIARIZATIONVISCOSITYDiesel fuel covers a broad group of petroleum-basedfuels ranging from crude oil to kerosene. Depending on theengine and its operation, these fuels will burn in a dieselengine. The m ajor difference in gas engines and dieselengines is in fuel source, compression ratio and fuel-air mix.(Fig. 1-1)Viscosity is an im portant physical property o f a dieselfuel affecting injection pum p internal leakage and lubrica tion and injector lubrication and atom ization.CompressionRatioFuelSourceFuel-Air Mix(intake)GasolineEngines8:1Carburetedair-luel mistDieselEngines20:1Injectedair onlyFig. 1-1Because o f their design and use, Chevrolet dieselengines use a narrow range o f diesel fuels. These fuels arerated at N o. 1-D, N o. 2-D and W interized o r BlendedNo. 2-D.A characteristic o f diesel fuel rating is Pour Point andC loud Point. P araffin or wax is a com ponent o f diesel fuel.T he Cloud Point represents the tem perature when the wax indiesel fuel begins to crystalize and separate from the fuel.T he P o u r Point represents the tem perature when the waxcrystals interlock and fuel cannot be pum ped. The fuel isheld in suspension like a sponge holds water.No. 1-D fuel has the lowest cloud point and pour point( - 2 0 F / - 4 0 F ) . N o. 2-D has a higher cloud point andpour point (20 P /0 F ). Blended or winterized No. 2-Dvaries between the two based on the blend.Chevrolet recom m ends N o. 2-D whenever ambient(outside) tem peratures are above 20 F. During cold weatherm onths, N o. 1-D should be used. If blended or winterizedNo. 2-D is available, it can be used instead o f No. 1-D.(Fig. 1-2)Rated FuelAmbient TemperatureAbove 20 FNo. 1-DNo. 2-DBelow 20 FApproximatelyCloud Point (-20 )Pour Point (-40 )ApproximatelyCloud Point (20')Pour Point (0 )Blended No. 2-DCloud Point (Varies)Pour Point (Varies)Fig. 1-2DIESEL FUEL CO NDITIONERSA num ber o f diesel fuel conditioners o r m odifiers arecommercially available. Chevrolet does not recommendtheir use in cars and light duty trucks. A lso, the practice o fmixing unleaded gasoline with diesel fuel to reduce cloudp o in t/p o u r point is not recom m ended, regardless o f pre vious inform ation that suggested it.The minimum viscosity is limited by the need foradequate injector and injection pum p lubrication. Lowerviscosity fuels are thinner and therefore will cause a higherrate o f internal pum p and injector leakage and injectordribblings which can lead to loss o f power o r smokeproblem s.Since viscosity influences the size o f the fuel droplets, itgoverns the degree o f atom ization and penetration o f thefuel spray. These are m ajor factors in obtaining sufficientmixing o f fuel and air essential for proper com bustion. If theviscosity is too high, the fuel droplets will be to o large forproper mixing and poor com bustion will result. A lso, thedroplets may strike the relatively cold cylinder wall and failto burn. If the viscosity is to o low, the fuel spray will nottravel across the com bustion cham ber and the poor mixingwill result in im proper com bustion. P oor com bustion resultsin loss o f power and excessive exhaust smoke.CETANETechnicians should be aware o f cetane ratings for dieselfuel. Cetane ratings should not be confused with octaneratings for gasoline. Cetane can be thought o f as the ignitionquality o f diesel fuel. Generally speaking, the higher thecetane rating, the better the ignition quality. A high cetanerated fuel ignites quickly with short delay o r lagging.Conversely, a low cetane rated fuel will take m uch longer toignite, and may cause excessive knock and roughness.T he diesel engines currently used by Chevrolet are forthe most part insensitive to cetane ratings, due to the use o fglow plugs for a starting aid. However, the consistent use o fa high cetane rate diesel fuel will aid in the prevention o fengine knock.FUEL T R A N SF E R ANDFILTERING SYSTEMT here is little difference in the fuel tank and fueltransfer system between diesel and gasoline cars and lightduty trucks. Tank location and filler neck construction isessentially the same. O ne difference is in fuel tank caps. Thediesel fuel cap has a two-way valve which allows built up hotair to bleed o ff. It also prevents fuel spills in the event o f arollover. This cap is not interchangeable with gasoline caps,although the gasoline caps will fit the filler neck o f the dieselfuel tank.T he fuel tank pickup unit is somewhat different. Awater sensor, m entioned earlier, is included on m ost units. Asaran filter o r mesh sock is fitted to the end of the pickuptube. This sock filters large particles from the fuel andstrains m ost o f the w ater out o f the fuel. (Fig. 1-3)T he sock can becom e clogged when diesel fuel coolsbelow the cloud point. A check valve at the to p o f the sockopens when the sock is clogged, allowing fuel to pass. If thefuel level drops below the check valve opening, a no s ta rt/

“run” or “start” position. The ground circuit is completedthrough the pump mounting bracket or through a lead wireto the threaded screw. The mounting surface must be cleanand tight for proper pump operation. Maximum operatingcurrent is 3.0 AM PS. At the pump’s maximum pressure, itwill shut off. It will again turn on at it’s minimum pressure.The pump is mounted to a stud bolt on the left bank o f theengine. (Fig. 1-5)NOTE: No external mechanical or electric fuel pump isneeded on the 2.2 or 1.8 liter engines, since the supply pumpin the injection pump assembly is adequate. There ishowever, a hand-operated priming pump incorporated in thefuel separator on the 2.2 and 1.8 liter engines.Fig. 1-3 Fuel Tank Pick Up Unitout o f fuel condition will occur. Therefore, drivers mustkeep at least a quarter tank of fuel in the vehicle duringwinter months.NOTE: The LUV truck is not equipped with a checkvalve at the sock on the fuel pickup unit.FUEL PUMPSFig. 1-5 Electric Fuel PumpFuel pumps or fuel lift pumps draw fuel from the fueltank and pump it into the fuel injection system. Fuel pumpsmust keep fuel flow constant when the engine is running.Chevrolet uses two types o f pumps; a conventional mechanical/diaphram type and an electric type.FUEL FILTERSFuel filters strain contaminants from the fuel prior tothe fuel reaching the injection pump. All diesel engine carsand light trucks have a primary fuel filter. The 6.2 liter dieselengine also has a secondary filter.The mechanical/diaphram type is found on the 6.2 and5.7 liter diesel engines. They are located on the front, lowerright side o f the block. The 6.2 liter pump is driven by aneccentric lobe on the camshaft through a pushrod. The 5.7liter pump is driven by a lever o ff the crankshaft. (Fig. 1-4)The primary filter for the 6.2 liter engine is mounted tothe cowl. A drain petcock is located on the top and bottomo f the filter. Opening these petcocks will drain any wateraccumulated in the filter. A short length o f hose is attachedto the lower petcock to direct fluid away from the enginecompartment.The electric pump is used on the 4.3 liter engine. Itreceives battery current anytime the ignition switch is in theFig. 1-6 Stanadyne Fuel Filter1-2