Testing an oil injection system

Testing an oil injection system

by Conrad & Judy Kreuter

Q: Dear Boat Talk: I have just purchased a used 90HP Evinrude engine with oil injection feature. I have always mixed my own oil and gas together and would like to do the same on this engine. Can you tell me how to eliminate the oil injection feature? Old Fashioned, Centerport NY.

A: Dear Old Fashioned: It sounds like your fear of oil injections feature on this motor comes from the fact that you do not know if the system is working properly. Here is how you can tell if it is. Fill the oil tank almost to the top and make a mark at the oil level. Prepare an additional amount of oil and gas mixture the same as your have always done in you gas tank. Then run the boat for a few hours under normal boating conditions. Check the oil tank to see if the oil level has gone down. If it has the oil injection system is working properly.

The purpose of the oil injection system is to allow the proper amount of gas to oil ratio at various operating speeds. At idle speed the oil injection system supplies a ratio of about 100:1, at full speed the ratio changes to 50:1.