Fuel odors can be difficult to find, especially if they are in an airflow stream. I even ran mine with the cowl off trying to locate mine. I did not see the source at first, but I did notice a fine mist in a very small area on the windshield. Further examination identified a leak at the banjo fitting and return line. That line takes a very tight 90 degree turn at the banjo fitting before heading back to the fitting on the firewall shelf, and with no clamp on that hose, it is very susceptible to a leak. The airflow over the top of the engine will carry that tiny amount of fuel away, leaving no evidence. I added a clamp to that hose, at the banjo fitting, and my problem was solved. Hope that helps............Tom