Bombardier SeaDoo 1990 factory shop manual, Page 72Get this manual
Section 04 COOLING SYSTEM Sub-section 03 (CAREFLUSHING)
NOTETo allow more efficient flushing on watercraft equipped with flush kit, install hose pincer (PIN 295 000 076) between T-fitting and exhaust socket This will prevent water exiting through exhaust socket
3 Start the engine then immediately open the water tap CAUTIONAlways start the engine before opening the water tapOtherwise, water will back flow through tuned pipe into the engine and may the cause damage internal partsOpen water tap immediately after engine is started prevent overheatingFolllow this procedure exactly