My 52 did the same thing years ago when I got it. Thinking it was the carb, I had it rebuilt. Did the same thing. Had it rebuilt again: and again the same thing. Figured the carb was worn out so I bought a reman. one at the parts store. Did the same thing. Took it to an old mechanic that new about these vintage trucks. Found out that the fuel pump was bad. Replaced the fuel pump and the problem was solved. I don't know if this is what is wrong with yours but you may give it a try.


John Kinser