1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 97Get this manual
Fuel System Trouble Isolation Chart (Cont Step 4Check Carburetor Remove air silencer coverSqueeze primer bulb until it firms upInspect throat of carburetor for floodingResult Primer bulb firms up, no floodingGo to step 6Primer bulb does not firm up, flooding presentRepair carburetor(s)Primer bulb does not firm up, no flooding presentGo to step 5Step 5Test Fuel Pump After checking the fuel system and all leaks are corrected and filters cleaned, connect fuel pressure gauge between fuel pump and carburetorRun engine at wide open throttle (WOT) Pressure should read 17 kPa (2.5 psi) minimum Result Fuel pump OKGo to step 6Not OKReplace fuel pumpStep 6Check Adjustments Adjust carburetor linkage and throttle camSee Section 1, Engine Synchronization and AdjustmentsTest motorResult Motor not OKCheck timingSquirt fuel in carburetor's throatDoes engine start? If not, suspect ignitionTiming OKRemove and service carburetor and leaf valve assembliesStep 7Check Primer System Manual Start Modelswith engine running approximately 2000 rpm, stroke primer knob to timesEngine should run rich and drop approximately 1000 rpmElectric Start Modelswith engine running approximately 2000 rpm, push in keyEngine should run rich and drop approximately 1000 rpmResult Primer not OKCheck solenoid resistance, check for pinched fuel hoses or blockage of injection nipple at carburetor base with OMC Special Tool PIN 326623 (Nipple Cleaning Tool)