[Motor31]

Is this happening when you use the fantastic or vent fan set to pull out air from the rig? I found that any use of the fan in warm weather to pull air from the trailer tends to cause the black tank to vent into the trailer. IIRC drv used a slip style method for mounting the toilet onto the black tank. In other words there is no real seal in the down tube into the tank, just the overlapping of the down tube and the black tank intake pipe. For the most part that works but it will tend to "leak" fumes if there is a lower pressure in the rig by using the fan on outflow, even with windows open. Since the tank tends to produce gas anyhow it is already slightly higher in pressure so any oportunity to vetnt into the rig is going to bring in fumes.

Bringing the fumes in that way would "favor" the pocket door area over other avenues since one of the ways air enters the rig is through the access hatches. They really don't seal well at all.