If the coach was running great when parked, you should not need to rebuild the carb. It may be a little varnished from the evap of gas that was in it, but should not be too bad. Suggest mixing 1/4 cup fresh gas and 1/4 cup Seafoam (or MMO) and pour it into the round vent at the top of the carb. Let sit for a few hours, at least. That should dissolve all varnish and leave your carb as good as it was when parked. It is OK to start the engine on this mixture. It will give you a little white smoke for a minute or two, but will also lube the valves nicely. Regarding fuel filters, I installed a Fram G3 filter in the rubber line leading to the mechanical fuel pump (mount it low for easier access). It has the same filtration spec as the tiny filter in the carb base, but 10 times the capacity for rust, and is MUCH easier to replace. It is also transparent, so you can see if it gets loaded up. I would not worry too much about 3 year old gas. A bottle or two of Heet or Seafoam should take care of any water that has collected (probably not much since the tanks were full). The octane rating may have gone down a little, so don't push it too hard until you can add a half-tank of fresh gas. As someone mentioned, keep an eye on the gas filter as you'll most likely get a slug of rust from the tanks. but after a few hundred miles of driving , that should slow down. 'Good on ya" for keeping the coach in the family and enabling a new generation of GMC lovers!
Last edited:
