Mixture control

[ketter1]

After landing tonight the engine seemed unusually rough. The four hour flight was uneventful. The rough engine resolved on increasing the throttle but got rough immediately on decreasing the RPM. THe mixture was full rich. I could not get the engine to stop by leaning. In fact, it seems that the roughness improved pulling the mixture toward lean. Had to turn the mags off in order to stop the engine. Inspected the mixture cable afterward and it was attached and seemed to be working properly.
Any suggestions before the mechanic on the field starts pulling my Comanche 180 apart?

[charles Melot]

The primer is open or leaking or both!

[ketter1]

The primer had worked itself out about 1/4"

Thanks for the great advice

[charles Melot]

Cheap fix eh! Every once in a while there is one that it painfully obvious.