Re: 1999 Sunbird, 90 Hp Johnson
The 90 hp units that year had a combination oil/fuel pump stock from the factory. Your boat probably has a 1.8 gallon oil tank somewhere under the back splashwell. Add your oil there, and the pump will mix it with the fuel to the proper ratio. Some of the 88 hp units that year did not have a premix pump and you had to add oil to the gas tank. You need to check to see what model you actually have and if this pump is still operational. The proper ratio is 50:1, meaning one pint of oil to 6 gallons of gas. If you are unsure if the combination pump is working, premix your oil in the regular gas tank, mark a line on the oil tank and run the boat. (This will double oil the engine and it may smoke a little more..) If you note that the oil level in the oil tank is going down, you know the combination pump is working properly and you can discontinue adding oil to the fuel tank.
