We have normal aspirated O-470 with gravity feed fuel using an E. I. FL-5P fuel flow system with an FT-90 flow meter. We find that the fuel flow indications become intermittent especially with ambient temps below 55 deg.F. At times the readings are just fine for a period of time than they start...
No signs of leaks anywhere
Plane kept in a hangar
Odor is prominent in cabin when I open the door
Occurs if plane is left overnight. But not after short stops of say1 to 3 hours
No noticable outsie of plane even in the hangar