It has been a while. Here is where we stand.
Several times I thought the problem was corrected, only to have it rear it's ugly head again. Even though I got clear fuel out of the fuel tank drain, I decided it was time to remove the tank and fuel hose to insure it was clean. Turns out there was a good bit of sludge in the bottom of the tank. I cleaned an reinstalled it. Filled it with new fuel with conditioner and replaced the fuel filter. I was very confident that the problem was solved at last. I ran the tractor several hours, shut it down and tried to start. It would not start. Opened the fuel tank cap to insure it was vented. Still would not start.
Next day, I loaded it up and carried to JD dealer. They found a little trash in the hand priming pump check valve. They installed a rebuild kit. Said it was restarting when hot, but a little sluggish. Wanted to pull and check injectors, check compression and valves, and check starter rpm. Injectors were fine, compression better than spec, decided no reason to check valves and starter sounded fine. You can pick it up.
When I got there several hours later, they had continued restarting it hot and the problem was back!! However, it would restart with a little ether.
They had talked to several of their other shops and the shop they use to rebuild injector pumps. Consensus was that there was probably trash in the injector pump inlet screen. They could check it, but there was a "good chance that everything would fall out" and it would need to be rebuilt ( $900).
Injector pump is a Stanadyne Model # D9 DB4327-5563; Mfg. nbr RE-500441.
I am at a loss as to how trash got to the primer pump check valve. Wouldn't that be on the discharge (clean) side of the filter?
I am going to operate tractor, using starting fluid as needed, and hope the starting gets better.
Isn't it bad for an engine to regularly use ether to get it started?
Bill