2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 120Get this manual
POWERHEAD TEST PROCEDURES
Engine Oil Pressure Test
Check the engine oil levelRemove the oil pressure switchInstall an oil pressure gauge and adapter into the oil pressure switch hole
Start the engine and warm up engine as follows: Summer: minutes at 2000 RPM Winter: 10 minutes at 2000 RPM After warm-up, shift the engine into forward gear and increase the engine speed to 3000 RPM The oil pressure at this speed and normal operating temperature should be 58 to 72 psi (400 to 500 kPa)If the oil pressure is lower or higher than specification, the following causes may be considered:
Low oil pressure
Clogged oil filter Leakage from oil passages Defective oil pump Defective oil pressure regulator Damaged O-ring Combination of above items