1985 6.9 Injector Leak?
 

Ok guys, here's my first post.
I've actually been lurking on these forums for a while since I just got out of the Marine Corps and decided to buy my first diesel truck. I bought it for 2700$ with 500$ DMV back fees off a guy off of craigslist who said the reason the brakes were spongey because there was air in the lines. Turns out the rear wheel cylinders were both leaking into the shoes. 300$ worth of new brake parts later the brakes are fine.

Anyways,
I notice that when I idle for a long time I start to smell diesel, and also notice on start up that there is fuel leaking beneath the truck. When the truck is running it doesn't leak beneath it. I think it only happens when the injectors pressurize. I did some research and see that it is common for these trucks' seals to go bad with age and I notice that I'm getting terrible fuel mileage (10) city. Any thoughts? I already purchased the new injector seals on line just to be safe.

Congrats on your new truck. But It's very possible that your injector o rings are bad and they are probably due for a change, but I'd also check the fuel lines from the tank to the engine an also the return lines I've seen them leak like crazy and any other fuel line you can access if its leaking that bad to where it's dripping from the truck you should be able to see. Hope this helps!

yea it's definitely the injectors, I can see the injectors are leaking diesel

Well then I would just pull them and replace the o rings like you said you were going to do