Issue with furnace - smell un-burnt propane

[tentcamper]

This last time out we had nights in the low 40's. One night we came back to the camper after being out for 5+ hours and the camper was very cold. I turn on the electric heater and then fired up the furnace to warm it up quickly. All seem to work fine except it took several try to fire up the furnace. I did get a brief smell of un-burnt propane.

The furnace heat output was very low. Later via thermostat demand when it tried to fire up, it would get the spark but no flame. I had a little smell of un-burnt propane.

I figured out the issue and made the repair to the furnace not lighting. I inspected the combustion chamber and all seals. They all look good. It was a clogged orifices. All work well after and there was no smells.

My concern is that I could smell the un-burnt propane??? Since the furnace is a closed combustion chamber and only vented outside and I could smell the un-burnt propane inside???

I think what took place is my furnace vents are about 12 inches to the forward side of the door and with all the air movement from the fan it created a slight vacuum bringing in some of the gasses through the leaky seals around the door. Since you can not smell CO, i'm now concern how much of the CO is leaking back into the camper. I going to take a CO tester out next time and run the furnace.

Any body have this issue or any thoughts on it???