Advice appriciated

Hello there, I recently got myself a used coleman 424 for camping. I tested it at the seller and it worked fine (enough). The flame took a while to turn blue, but i thought a bit of tweaking the knobs would do the trick. I am on a campingtrip right now and it is not working. No flame at all be it yellow or blue.
In starting mode a bit of fuel drips regularly out of the generator pipe but it seems it doesnt make its way to the burner. What could be the problem?
- fuel is about half in the tank
- rubber seal at the pump looks old but might still be okay. The pump takes a lot of force. Should i replace the pump to get it working again?