9.9 Mariner 4-Stroke Problem ("making oil") [Archive]

FJH1

06-30-2003, 09:56 AM

I have a Mariner 9.9 4-stroke. About 80% of the time things are good.

I have a constant problem of the lower plug fouling - I think this is a common problem with this engine and the Mercury 9.9 4-stroke. After trolling I make a point of running the engine ay WOT for 5 minutes or so. After I'm done running at WOT I always disconnect the quick connect gas fitting, but I don't run the engine out of gas.

The other problem I have is that the engine will occasionally dump gas into the crankcase and "make oil". I have never run the engine out of gas after trolling, but now I'm wondering if I should unhook the gas line after trolling and run her at WOT until she runs out of gas. What do others do? Thanks in advance.

Best Regards,

FJH

Husky

06-30-2003, 11:06 AM

Are you sure the gas is getting into the crankcase via the carbs after shutoff? I'm only raising this question since there have been incidents of kickers never getting thoroughly warmed up enough (thermostat never closes) and the rings and cylinder walls have allowed fuel past them since they are not to running temp and clearances. I don't remember if Merc 9.9's have thermostats, but it's a thought in the troubleshooting process.

Husky

06-30-2003, 11:06 AM

Are you sure the gas is getting into the crankcase via the carbs after shutoff? I'm only raising this question since there have been incidents of kickers never getting thoroughly warmed up enough (thermostat never closes) and the rings and cylinder walls have allowed fuel past them since they are not to running temp and clearances. I don't remember if Merc 9.9's have thermostats, but it's a thought in the troubleshooting process.

FJH1

06-30-2003, 02:01 PM

Thanks. No, I don't know how the gas is getting in, could be the thermostat. Over the course of the years I've owned the engine it has only happened twice, but it is irritating.

Best Regards,

FJH

bobk

06-30-2003, 04:35 PM

I do everything the same as you but I let the engine run out of fuel. I have a Merc. 9.9. It solved my problem.
Bob

FJH1

07-01-2003, 11:19 AM

Thank you! I'll give it a shot.

Best Regards,

FJH