Small Engines (Lawn Mowers, etc.): Homelight generator surging, vacuum lines, fuel pumps

Question
Hello, I recently purchased a Homelight generator model LR4400 with a 8hp B&S engine, It was sitting in a neighbors garage for about three years brand new still in the box He sold it to me cheap because it would not run without surging unless the choke was on about 3/4. without the choke the engine surges badly, with the choke on it runs perfectly. I removed the carb and cleaned it but but it didn't need it I checked  for leaks  everywhere in the system but everythings perfect, if this was an older engine i'd try adjusting the carb but there are no adjustment to be made on this carb. I also checked the fuel cap vent.  Also this is the first engine i've worked on that has a fuel pump could you tell me why B&S started using these? I don't what  the problem could be.  Any Thoughts?                          Thanks.

Answer
If the carb has no adjustment then the governor spring may be bad.  Do you have a tachometer for small engines?  The engine needs to run 3600 rpm or it may surge.

Briggs have been using fuel pumps for years depending on the application.  The fuel pumps are fairly reliable. Are the vacuum lines on the fuel pump in good shape?

Let me know.
Eric