Hi everyone,

I have a 78' B300 with a 400, that we have put rebuilt carb on and new plugs, wires, cap and fuel filter. Runs great, until warms up then starts to hesitate and backfires back through carb and manifold. I've been told that the intake manifold has hard gunk built up inside, it's a camper van and sat for a prolonged period of time. My question, fuel pump? PCV and EGR? I've seen auto part sites that show a oxygen sensor but don't know if a 78 would even have one? Anyone have any ideas?

thanks!

Brad

 

Replace the electronic ignition module.