vapor lock or bad fuel pump ?

Michael, Since you haven't had a reply, I'll give you my thoughts.

You may have a poorly adjusted float in the carb. It goes without saying that you should also check on the location of fuel lines near the exhaust manifold and block and check on the condition of the sediment bowl or fuel filter if it has one. There is a lot of heat transferred directly to a fuel pump mounted on the block. I have tried insulating it a bit by using a cork gasket under the pump but with marginal results.

On the other hand, I think that a lot of vapor lock problems in older cars are partly caused by current gasoline formulations, not mechanical problems. I have had this problem even with newly rebuilt fuel pumps. Oil companies no longer need to worry about fuel volatility since virtually all modern cars have high pressure fuel injection systems and electric pumps. So I believe that modern fuels vaporize more readily.

Mechanical fuel pumps draw fuel from the rear of the car under low pressure as opposed to being pushed up the fuel line by a rear mounted electric pump. You said you had an electric pump in the car as well. Even the flow-through pumps add additional resistance in line when not in use, and it's possible that the combination of fuel line resistance (especially in a car with small diameter fuel lines line an Auburn) and modern fuels will cause a car to vapor lock even when it didn't in the past. This kind of problem should show up the most under higher revolutions when the engine is drawing the most fuel. Not much you can do about it except run the electric pump?that's why it's there.

I have a 1931 898-A Auburn sedan. Runs great especially in cooler weather. In hotter weather and after the engine has warmed up it frequently sputters and I briefly run the electric fuel pump and the engine recovers promptly and runs normally for a variable period of time. This happens frequently and there must be a solution. Does it sound like vapor lock ? If so any suggestions ? Does it sound like a faulty fuel pump ? There is absolutely no problem whatsoever in cooler weather or after the engine runs for the first few miles.

I'm no mechanic so appreciate your advice. MA