1990 Johnson Evinrude "ES" 9.9 thru 30 Service Manual, P/N 507871, Page 38Get this manual
Preseason Service 1Check gearcase lubricationIf leakage is evident, gearcase seals may need attentionCheck lubricant level in power trimtilt reservoir"See Lubrication, this section 2Apply light coating of OMC Triple-Guard grease to the ribbed portion of the spark plug ceramics and the opening of the spark plug covers Connect spark plug leadsMake sure spark plug boots are not cracked or torn
3Check water level in battery, then chargeWhen the battery is charged, the acid solution inside the battery gives off hydrogen gas which can explode if ignited by spark or open flameIf hydrogen gas is not able to leave the battery (vents are clogged), the battery itself may explode Therefore, when charging batteries, make sure that battery is vented to atmosphere and lots of fresh air is in the areaMake sure no sparks or flames are presentDo not short across battery terminals to check battery conditionInstall and connect battery