I have a 9.8 Mercury with thunderbolt ignition. Serial number is 5881949. Can someone tell me the year of this motor. I am thinking its a 1983 and the hood has the blue strips. I am hoping to order parts as I am trying to determine the cause of a problem. Motor has cranked easily until recently. Now it takes a few times running for it to warm up and stay running. At idle and while running motor will knock one time and then bog down before catching back up. Additionally since I have had it I can only run 7-8 mph per my graph GPS; however, last week something magically happened and the motor ran super smooth, quiet for a 2 stoke, and I got on plane for the first time ever while the graph read 12mph. Shortly after it dropped back down to 7-8 mph. Any ideas what may be causing the motor to sound like it straining to produce 7-8 mph when I feel like I should easily be getting 12mph.
Thanks in advance for any and all input.
Justin
Thanks in advance for any and all input.
Justin