mercury 225 idle rich carbureted

[stevewam]

1997 225 loads up at idle, right side plugs nice brown and lt side white??? runs good planed out after flooding clears out. need help

 

[Chris1956]

White could mean overheat. Brown is usually a good sign.

Does that motor have a pulse driven fuel pump? If so, the fuel pump diaphragm can leak putting raw fuel into the crankcase at idle. This fuel usually burns off at high RPM, if you can achieve high RPM.

 

[stevewam]

White could mean overheat. Brown is usually a good sign.

Does that motor have a pulse driven fuel pump? If so, the fuel pump diaphragm can leak putting raw fuel into the crankcase at idle. This fuel usually burns off at high RPM, if you can achieve high RPM.

just rebuilt fuel pump, no luck

 

[stevewam]

just rebuilt fuel pump, no luck

anything above idle and runs great all day long

 

[Chris1956]

OK, Other causes of flooding are carb floats on one side set too high or inlet needles bad on one side of engine? Idle mixture set wrong on one side of engine? Weak spark at idle on one side of engine (not sure if this is possible)?

You might check the thermostats. Maybe one is stuck causing overheating?