FT9.9 4 Stroke test tank

Hi there,

I've got a 1989 FT9.9 4 stroke, and I made a test tank out of a 275 gallon tote. It seems to work great.

However I noticed after running at high throttle for a while that the engine started exhausting white smoke and dribbling out a nasty sticky black gunk from the upper exhaust hole. I've had other issues before, but this is the first time experiencing this. It's had good (119/110) compression in the past but I don't have a tester and so haven't checked since running in the test tank.

Is it possible that running in a test tank with a normal prop (it's a high thrust motor) presumably at low RPMs could cause this issue?

I also just rebuit the carb, which resolved another issue but could theoretically have caused this. My first instinct was to check float bowl height but it was fine.

Any ideas? Thanks!

check termostat.if its not reach right temp so pistons will not expend

Hi raczekp1, the motor has a couple of bimetal things that are used for starting, but it doesn't have a thermostat that's used when the engine is a temp. When I put an infrared gun on the block it shows about 175 degF when run under load.