Hey everyone, I was out fishing today with my 4 stroke Mercury 9.9hp motor. It was giving me some attitude, and wouldn't run for longer than 4-5 min before dieing. I brought it home and went through the fuel lines and inline filter and it was plugged! Barely any fuel would've gotten through. So I cleaned it all out, it was rotted tube from inside the fuel tank where it sucks it up and out to motor. My worry is did it do anything to my motor? I pulled the plugs and attached pics of them below. They are old plugs that should of been changed awhile ago. But I'm worried that there was so much oil present on the plugs, is that normal? Do I have bigger problems? Also when I was "milking" her back to the ramp I had to partially choke it, would that cause this on the plugs? Thanks for any input! .
Shouldn't be any oil on the plugs in a four stroke. What your probably seeing on the plugs is unburned fuel since you said you had the choke on. Golden brown plugs-normal, white anode-too lean, dark or no color-too rich. Shouldn't of hurt the engine. Four strokes are a little more forgiving about running too lean, but running a two stroke too lean would have caused some problems. When you get it fixed and running again, run it like you normally would and if you see white smoke coming out the exhaust that means you have problems. Black smoke- running too rich. Hope that helps
The oil on the plugs is a normal sign for a 4 stroke. As far as damage to the engine, I would change the gas lines out and check for function. There is a good chance that you were just starving the motor from having the deteriorated line and not allowing enough fuel into the intake. You should have a hose attachement for cooling the engine while not in the water. Start your engine with the hose attached and listen for anything abnormal. In case you hear something objectionable, turn it off and take it to your favorite mechanic.
Featured Fishing Sites: