This May be My Stumper

If you own something...A 1999 John Deere 345 54" deck. In those 16 years with very few mechanical problems, you know there will be a time when the "big" one will occur. This happen on Wednesday July 15th when I was mowing the 7 acres. With about three minutes left in completing the mowing chore, the engine quit. First thought...out of fuel. Checking the tank, find I had enough to complete the job, However, I went to the garage and got the gas can and made the 500' walk back to the tractor to fill the tank. No start... waited couple minutes and tried starting once more...No start. Waited once more due to the 98 degree temp. thinking I let the engine cool just in case it may be a vapor lock. Tried several times and still no start. Got the other JD tractor and pulled it home and in the garage to be worked on.
Come Thursday morning it became time to see what the problem would be. Knowing there's that all trouble one...the Time Delay Module gone bad again. It is best to have a spare handy with these TDM parts. Install it and again...No start.
In my old age, always found when an engine won't start, it is spark or fuel related. My guess it is the fuel pump or the gas tank is dirty and fuel pickup tube is clogged up. So, removed the seat, rear body, and removed the gas tank. Cleaned it out and air blew the pickup tube and all the gas lines, and replaced the fuel filter. Still no start. no gas seem to be flowing from the tank.
I remembered I had the factory installed fuel pump that didn't have the drain hole when John Deere sent out the warning to replace the fuel pump with a newer version. I installed it on Kawasaki FD611V and again no gas is being pump into the carburetor. There's an old saying when I was growing up...there are other ways to skin a cat.
Removed the rubber hose to the carburetor and with a small container of gas filled the carburetor bowl. Got on the seat and turned the key...Started right up. Tractor ran until the carburetor bowl went dry. Repeated the same procedure and once again the engine started and ran. Repeated this four times, and realized the fuel pump is bad. Wait a minute, this is the fuel pump that I removed due to the leaking problem, and it ran find until I replaced it.
Question! Is this a fuel pump issue or a broken cam on the camshaft that moves "actuating" the plunger that moved the pivot arm in the pump?

If this be the problem... bad or broken cam that will not actuate the plunger rod. If so, nothing else to do but tear the engine down.... or dump the 16 year 345 and and spend a few bucks for a new lawn tractor.

Sorry for the long thread.