force 15 hp---need some advice!

[automechanic]

I have a 1988/89ish Force 15 hp that does not idle. It is running extremely rich on the lower cylinder, fouling out the plug. Can anyone help? We have been through the carb, all new fuel lines, pulled the exhaust plate-all ports are clear, and pulled the fuel drain plate off-cleaned the screens-cleaned the ports. Can someone tell me if the cover plate with the screens has 2 check valves in it? Looking at the parts diagram it should have, but I can blow both ways through each port. Is this normal? I can start the engine ok, revs up ok, it does smoke excessively, even at full throttle in gear it smokes a lot. The motor also seems to have a lack of power, at top end it feels like a 5hp. If I bring it down to idle, it "pops" and then dies, in gear or out of gear, and after sitting for a while you have to hit the primer before it will restart and then rev it up for a minute before it will run in gear. I am running mid-grade fuel, 50-1 oil ratio.

Any ideas?

 

[jerryjerry05]

Re: force 15 hp---need some advice!

In the carb.The main jet has small holes in it these are the low speed idle.Set the air screw at 1 and 1/8th turn out then adjust.
Do a comp test.Then a spark test.Check the spark while running. Inline testers work best.
Ethanol is messing up a lot of motors.It's delaminating the inside of older hoses causing clogs in the carbs and fuel filter.Check for soft hoses and junk in the filter on the motor.Check the diaphram,fuel tank hoses and squeezie. J

 

[automechanic]

Re: force 15 hp---need some advice!

Thank you for the quick reply, question, if I had a carb issue, wouldn't it be fouling both spark plugs? All of the fuel lines are new, the filter is clean. I have checked spark, but not with it running. Any thoughts on the cover plate with check valves? If those are supposed to be check valves and they are stuck open, would the fuel just run and puddle in the lower cylinder?

 

[automechanic]

Re: force 15 hp---need some advice!

I don't know if anyone is having this problem too, but I was able to locate a new drain cover/check valve assembly. I replaced it, problem solved. My best guess is that the faulty check valves allowed fuel to run back into the lower cylinder, causing it to go extremely rich at idle. I have it running great in the bucket and am anxious to see how it handles on the water.