1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 74Get this manual
Trouble Check Chart (Cont TROUBLE 3lOSS OF POWER (Providing Ignition OK) (Cont) EPOSSI BlE CAUSE OVERHEATING POW ERHEADSee Section Thermostats damaged Thermo cover or gaskets damaged Pressure control val ve damaged Exhaust cover gaskets Ieaki ng Head gaskets leak ng (warped head) (water in cyl inders) Water intakes obstructed Pump housing air bleed restricted Water passages obstructed Pump plate not sea ing (bottom) Pump mpell er damaged Motor too high on transom Pump housing distorted (overheating) Pump housing cover seal worn (driveshaft grooved) Water tube grommet damaged
FGEARCASESee Section Propeller hub slipping Bent or worn propel Ier Bent gear housing or exhaust housing Incorrect propel Ier 4ENGI NE MISFIRES ASPARK PLUGSSee Section Cover or inn er termina damaged (terminal point out of H.Tlead)Fau ty Ieads or crossed leads loose spark pi ug (low torqueDefective spark plugs (cracked insulatorIncorrect spark pi ugs BIG NITIONSee Section Incorrect timingoose wi ring (connectors improper ly joined) Coils damaged Arcing around ignition coilsloose connections to sensor coi ls, charge coilsignition coils, or on power pack ground lead leads roundi ng ut on sensor coi Is, charge coils, ignition coils, or key sw tch Sensor co il Charge co Is Power packs Arcing in key switch CFUEL SYSTEMSee Section Re irculation hose plugged or pinched Recirculation nipple plugged Recirculation check al ve stuck open Reci rcu lation hose not routed correctly causing rest ri tion Manifold check va lve plugged or restricted Carburetor idle system has foreign particles in passagesPrime va lve seat has foreign parti les on seat and wi ll not shut offCarburetor fI oodi ng Fuel pump diaphragm leaking into rankcase Primer bulb check va lve not operating DENGINE SYNC HRONIZATION AND ADJUSTMENTSSee Section Throttle plate synchronization andor throttle can pickup incorrectl set Eng ne dl speed set too low Check these items if engine sta lls