2005 Yamaha F90TR 90HP Outboards Factory Service Manual, Page 162Get this manual
Upper case
Removing the upper case
1Place drain pan under the drain hole, and then remove the drain bolt and let the oil drain completely
Checking the oil pump
1Check the gear teeth for cracks or wear and the oil pump case for scratchesReplace the oil pump assembly if necessary2Check the shaft for cracks or wearReplace if necessary3Check the oil passage for dirt or residueClean if necessary
Assembling the oil pump
1Install new oil seal into the oil pump cover to the specified depth2Remove the oil pump assembly and mount covers3Disconnect the ground lead and speedometer hose4Remove the upper and lower mounting nuts, and then remove the upper case