Hey guys - I’ve been fighting a vapor lock / heat related fuel delivery issue with my truck for a bit and I’m looking for help in resolving it.

I’ve got a basic street / strip 440 D150. Current fuel set up is a 3/8 line to a mechanical pump dead headed into a 750dp - no regulator or return line and no insulation or heat shields. You can probably guess where I’m going with this.

The issue rears it’s ugly head on hotter days about 30ish minutes into a cruise. You can steadily watch the AFR gauge go from 13-14:1 cruise to 12:1, 11:1 and finally around 10:1 where it will cough and die while rolling down the road. To me, it seems as if the fuel is literally boiling over out of the carb.

Anyone run into this issue? What are my options to solving this? As to be expected, I’m on a budget so I’m looking for the low hanging fruit vs reworking the whole fuel system.

Thanks in advance!