Tractor Repair: Ford 3000 gas tractor, holley carburetor, vacuum leak

Question
I have the above mentioned tractor, and up til 2 days ago, no problems whatsoever. Now, it seems like its not getting the gas to the spark plug or into the cylinder. I suspect it is the fuel pump, which is mounted on the front of the engine just behind the generator. But, I'm not sure. I took the line off at the pump and blew air back thru to the tank, in case of the screen being stopped up. This tractor has the Holley carburetor and is the 3 cylinder. I have bought a rebuild kit for the carburetor but I hate to do that and still have the same problem. Is there a way to determine if it is the fuel pump? I am getting gas in the bowl of the carb, but it just seems that the venturi is not sucking the gas thru like it should. But is this a carb problem or a pump problem? I am getting spark on the plugs, but they are dry after extended cranking. Sometimes it will start and idle for 25 seconds maybe and then just dies, like it runs out of gas. You cannot touch the throttle or it will die. Thanks in advance for any help. Steve

Answer
  Even though you blew air back to the tank, check the flow of fuel from the tank anyway.  The fuel line has to run full stream, a small dribble is not enough.  Remove the outlet line of the pump and crank the engine over.  If the pump is working, the fuel should surge out with every stroke of the pump and not just run a steady stream.  Make sure the choke is closing all the way or it will not start.  Check that the intake manifold bolts are tight or you could have a vacuum leak.  If everything checks out OK, take the carburetor apart and clean everything making sure all passages and jets are not blocked.