Residue on Bottom of Cowling

[flyingfrog]

There is a black residue forming on the bottom cowling on the pilot's side of my 140. Based on location, I would think that it is an issue with the electric fuel pump or gascolator. However, it is very black, and I would expect unburned fuel to show up with a blue stain. There are some traces of it on the firewall, but I can't find it anywhere else around the engine. It feels oily, but I can't find any leaks, and the consumption is very good. Any ideas what this could be?View attachment ImageUploadedByPiper Forum1478920443.591036.jpg

 

[flyingfrog]

 

[kf6iat]

 

[flyingfrog]

 

[kf6iat]

 

[Domenick]

 

[Sandpiper]

 

[Sandpiper]

 

[Avidflyer2]

 

[gusve]