Skid steer fuel problems

Just getting started on this site. Located y'all while searching for help with my Bobcat skid steer loader. Loader has a Kubota V1702 engine. I have owned it for 20 years and have had no problems from engine. Recently, it started stalling out after 10 to 30 minutes of run time. After checking fluid levels and general operations, I used the bulb in the fuel line to prime the system and it started right back up, but then stalled again. I have changed the fuel filter and checked the lines for connection and blockage. Everything seems fine and the engine starts and runs great, for 10 to 30 minutes. A few pumps on the bulb and the thing comes back to life.
There was a post earlier about a similar problem that turned out to be bad fuel. This doesn't seem to be my problem, but I learned that the round 'pump' on the side of the injection system is a transfer pump. How can I troubleshoot this problem? Is the problem really a fuel problem? Not much experience with diesel engine repair and troubleshooting (yet).
Any help would be appreciated,
SemperFiFarmer

I'm no diesel mechanic either, but I wonder if there's a lift pump that gets the fuel from the tank to the injector pump that may be acting up on you?
With any luck Rick B, brain 55, soundguy or one of our other mechanical gurus will come along and help you out far more than I ever could.

Use a combination low pressure/vacuum guage, barbed fitting Tee, and short piece of fuel line. Disconnect and Tee into the inlet of the diaphragm pump and run until it starts to die. If the guage is showing any vacuum the problem is between there and the tank - pinched hose, plugged/restricted pickup screen in tank, or plugged vent in fuel cap.
If no vacuum showing, move the test guage to the outlet of the pump - With the guage "Tee'd into the outlet pressure line and engine running at full throttle you should see 3 - 6 psi on guage. Plug the guage directly on the outlet to block the fuel line and crank engine pressure should be 10 psi or more.

Thanks,
Once I get the guage, I'll make those checks.

Thanks for the help. All indications showed the transfer pump was not working properly. Changed the pump, but the problem did not go away. The fellow at the dealership where I bought the pump asked about the pick-up line in the tank, but since fuel was coming from the tank, we eliminated that possibility. Guess what, the pick-up line was cracked and sucking air. It fell apart as I was removing it from the tank.

Thanks for posting the fix and glad to see that you got the problem solved. Folks here like to see the outcome in case any of us runs into a similar problem sometime down the road.