introduction to propane-fueled

mowers

and

troubleshooting propane-fueled

mowers

Backfiring1. Backfiringmaybecaused

byamechanicalproblemwithavalveorrockerarm.Checkthem.

2. Backfiringmayalsobeduetoanoverheatedsparkplugcausedbyanimproperlyadjustedair-fuelmixture.Checkandadjustthemixture.

3. Backfiringatidlemaybeduetomechanicalfailure.

4. Backfiringunderloadmaybecausedbyanoverheatedorwornsparkplug.

5. Backfiringthroughtheintakevalveisnotcommon.Itisusuallycausedbyafailedrockerarmorpushrod.

6. Backfiringduringdecelerationisduetoanover-richfuelmixturefromacloggedairfilter.Checkthefilterandserviceasneeded.

Propane Odor1. Iftheoperatorsmellspropane,thereisaleak.Propane

smellsthesameasnaturalgas,becausethesameodorantcompoundisaddedtobothfuels.

2. Closethecylinderservicevalveandcheckforleaks.3. Useapropaneleakdetectororanapprovedliquidleak-

checksolutionthatactslikeasoapywatersolution.4. Ifodorispresentatalltimes,checkthecylinder,valves

andconnectorsforleaks.Ifodorispresentonlywhileengineisrunning,thentheregulatordiaphragmisdefective.Rebuildorreplacetheregulator.

5. Ifthecylinderservicevalveisdefective,haveapropanesuppliercheckthevalve,pumpdownthecylinderandreplace.Donottrytoreplacethevalveduetothepressureinthecylinder(typically100-200psi).Donottrytotransferthefueltoanothercylinder.Yourpropanesupplierhasspecialequipmenttoevacuateacylinder.

Liquid Slugging1. Sluggingonlyoccursinvaporfuelsystems.Ifamoweris

operatedonanextremeincline,liquidfuelmayentertheregulatorfromthevaporwithdrawaltube.

2. Checkthatthefuelcylinderisavapor-servicecylinder.3. Checktheorientationofthefuelcylinder(locatorpinin

neckringlocatorhole).4. Ifastrongodorofpropaneexists,thepressureregulator

maybefrosted.Thisisastrongindicationofliquidslugging.

5. Ifsluggingoccurs,shutoffthemower,closethecylinderservicevalve,andallowthefueltodissipate.

6. Ifsoequipped,checkthehydrauliclinestothevaporizerforthecorrectconnection.

7. Ifthefuelcylinderisthecorrecttypeandsluggingpersists,substituteafuelcylinderthatisknowntobegoodandre-checkoperation.

For More Information

PropaneSafety:www.propanesafety.com

NationalStandards:NationalFireProtectionAssociation58,Liquefied Petroleum Gas Code,2011ed.(NFPA58).Chapters5and11covercomponentspecificationsandengine-fuelapplications.Tovieworordercopies,visit www.nfpa.org.

StateandLocalCodes:StateandlocallawsmayexceedorsupersedeNFPAstandards.Contacttheauthorityhavingjurisdictioninyourareaforrequirementsapplicabletopropaneorpropane-fueledequipment.

6. IfyouareapprovedbyU.S.DOTtore-qualifycylinders,followDOTproceduresandrecordkeepingrequirements.Removethecylinderfromthemower,informtheownerandrecordthecylinderserialnumberanddate.

7. Inspectfuellinesfordamage(UVdeterioration,abrasion,oilsoaking).Routelinesawayfromsharpedges,movingpartsandhotsurfaces.

8. Heatinghoses(ifequipped)–inspectforleaksandproperrouting.Replaceanydamagedhosesorhoseclamps.

troubleshooting a propane mower No Start

1. Checkforfuelinthecylinderbyopeningthefixedliquidlevelgauge.

2. Checkthatthefuellockoffisenergizedandthegroundwireisconnected.

3. Checkthepressureregulatorforfailedinternalparts.Removeregulatoranddisassembleonabench;inspecttheinternalvalvesandseats.Repairorreplaceasnecessary.Iftheregulatoristamper-proof,replacetheregulatorassembly.

Loss of Power1. Checkthattheenginecanrevtofullspeedwithnoload.

Adjustthrottlecableifnecessary.2. Applyalightloadtoseeiftheenginecanpowerupto

fullspeed.Ifitcan’t,checktheairfilter.3. Checkthemaximumgasflowcontrolonsystemsthat

aresoequipped.Ifprovided,adjustforproperfull-throttlepowerandemissions.

Engine Quits1. Anenginethatquitslackseitherair,fuelorspark.2. Lackofair:Disassembleairfilter;inspectandclean.3. Lackoffuel:Check

fuellockoff.Thelockoffiswiredinserieswiththechassissafetyswitches.

4. Checkfuelfilter(ifpresent).Propanecanpickupredrustfromstoragetanksthatcanplugafilter.

5. Lackofspark:Ignitionfailureistypicallynotduetopropanefuel.Checktheenginemanufacturer’sservicemanual.

Overheating1. Overheatingisusuallynotfuel-related.2. Checkforlawndebrisblockingcoolingfins.Checkfor

damagedcoolingshroudordamagedfan.3. Usecompressedair(notapowerwash)tocleanthe

engine,approximatelyevery100hours.4. Inrarecases,overheatingmaybeduetoanair-fuel

mixturethatissignificantlyoutofadjustment.Usuallythisconditionisassociatedwithastrongexhaustodorandpoorperformance.Adjusttheair-fuelmixtureandrepairorreplacetheregulator,ifpossible.Mostair-fuelmixturesarenotadjustable.

5. Ifsoequipped,checkthemaximumgasflowcontroltoseeifithasbecomelooseorgoneoutofadjustment.

Misfiring1. Misfiringistypicallycaused

byanignitionfault.2. Checkthesparkplug,spark

plugwire,andignitioncoil.3. Checkthevaporhoseto

themixer(carburetor)forcracks.

4. Ifmisfiringoccursatidle,thenchecktheair-fuelmixture.Ifadjustable,adjustaccordingtothemanufacturer’sspecifications.

5. Iftheunithasasealedmixturecontrolwithtamper-proofscrews,thenreplacetheregulator.

continuted on back

introduction to propane-fueled mowers

Key Differences From a Gasoline Mower

• Thepropanefuelsupplymustbeturnedonwhenthemowerisstartedandturnedoffwhenitisshutdown,usingamanualvalveonthecylinder.

• Propaneisstoredasaliquidundermoderatepressure(100-200psi).Thepropanefuelcylinderisasealedpressurevesselthatmustmatchthetypeoffuelsystem(vapororliquidservice)installedonthemower.

• Propanevaporfuelsystemsincludeanelectricallockoff,apressureregulator,andapropanemixerthatreplacesthegasolinecarburetor.Allcomponentsofapropanefuelsystemarepropane-specificandmustbeapprovedforusewithpropane.

Components of a Propane Vapor Fuel System

Propane Conversion

1. Disconnectthemower’selectricalsystem.2. Removethegasolinetanks,fuellines,airfilterassembly,

fuelpump,throttle,fuelfilterandcarburetor.3. Retainthegasolinetanksiftheyaretobeusedfor

mountingmowercontrols.4. Pre-assemblethepropaneregulator,fuellineconnections

andmixeraccordingtothemanufacturer’sinstructions.5. Installtheregulatoronthechassis.6. Installthemixerandair-filterassemblyontheengine.7. Mountthefuel-supplycylindersecurelyonthechassis

withthelocatorpinintheholeontheneckringtoensurecorrectorientation.

Propane System Inspection

1. Checkcylindertype—vapororliquidservice.Vaporandliquidservicecylindersarenotinterchangeable.

2. Inspectthecylinderfordamage.3. Checkcylinderposition—locatorpininholeonneckring.4. Checkcylindermounting—cylindersecuredfirmlyin

place.Ifthestrapsarebroken,replacethem.5. Checkcylinderrequalificationdate.Ifthemonthandyear

onthecylinderismorethan12yearsearlierthanthecurrentmonthandyear,replaceorrequalifythecylinder.

Vapor Fuel Supply Cylinder

High-PressureHose

Fuel Lockoff

Pressure Regulator

Low-PressureFuel Line

Propane Mixer(Carburetor)