2001 Caterpillar 3126 only stays running when I'm pushing priming pump.

I did bypass the fuel tank. I disconected the water separating filter fuel line, and hook up a pigtail into a 5 gallon can with diesel. Still it's not pulling fuel. Thank you for any ideas.
Ps. Also, is there an easy way to see if the Huei pump is pumping the pick-up pump?

 

Thank you Sir for the advice I did what you said the can is working great. I really had no way to test the fuel pump itself but I figured it's a 2001 and while I've got that pump off I just went ahead and replaced it I am now putting it everything back together it is Monday January 30th in the afternoon and I will let you know. I'm still drawing everything out of the pigtail with the fuel tank sitting on the ground. I do have everything together. I did use the primer pump I do have pressure full pressure on the primer pump took a little bit but I got it doesn't seem like I have any leaks so I'm going to sign off right now and I am going to try and start it and see if it stays running if it doesn't I have no idea what problem is cuz I've pretty much done everything that has to do with the fuel system any ideas would be really helpful thanks guys and thank you sir I appreciate it!

 

How you doing sir Sorry it took me a while to get back to you. I replaced everything I had told you I did. I did pigtail the fuel line into a 5 gallon jug of diesel and primed it with my new primer pump (that I changed)
And fired right up stayed running for over an hour so I think I fixed my problem also I was going to mention to you that I did have the injectors rebuilt because I was getting some oil in the fuel tank Not knowing that I probably should have pulled the cups and did the cups as well So I'm hoping that all that will be okay,. Also my next project is replacing the dryer filter which is underneath the school bus Not sure if I told you what I'm doing is on a 2001 school bus but I haven't found anything online on how to rebuild or replace the filter inside that air compressor dryer which is underneath the bus just behind the driver seat on the frame. But I wanted to thank you again for your assistance I really appreciate it everything worked great and you have a great New Year and safe travels