1998 Johnson Evinrude "EC" 90, 100C, 105C, 115, 150, 150C, 175 60 deg. LV Service Manual, P/N 520210, Page 75Get this manual
Pulse Limiter Servicing
The pulse limiter for the VRO pulse hose passes normal pressurevacuum pulsesThe integral check valve in the pulse limiter closes in case of backfire to protect the pulse rectifier valvesTo allow normal pump operation and protect the VRO rectifier valves, the check valve must not be cloggedA clogged check valve might restrict VRO fuel and oil supply, causing serious powerhead damage1Remove the pulse limiter from the crankcase or pulse hose
2Inspect inside pulse limiter for carbon and replace valve if excessive carbon is found, or, backflush the valve with OMC Carburetor and Choke Cleaner to remove any carbon deposits