Furnace Exhaust question

Boddhisattvha wrote:
Hey all,
I'm pretty sure I already know the answer to this but there is a lot of really knowledgeable folks on here so I'm looking for a second opinion or suggestions.

1985 Hi Lo and I'm pretty sure the furnace is the original. I didn't use it at all last winter and just started turning it on again recently. I was outside training my black water tank while the furnace was running and I smelled propane. Faint but definitely propane.
Now this is only outside the trailer. There is no smell whatsoever inside and after investigating it is coming directly from the exhaust port of my furnace.

It's a Suburban furnace that lights itself so there's no pilot I can adjust. Is there some other adjustment I can make to it? Is the smell in the exhaust normal? I'm pretty sure I should never smell propane but I could be wrong. Or do I just need a new furnace altogether? I've replaced just about everything else.

Just to be clear
1. Only smells when the furnace is running.
2. Only smells outside the rig
3. Smell is faint but definite.