Your pump is putting fuel out so its not bad, it’s just not cranking quick enough to build pressure to fire the injectors. Dropping down to 7 or 6 volts means your batteries are not up to *****.
Some people think ether is poison, but it really helps and is the only way sometimes to get these things going. One thing adds to another, the fuel system is dry, it's cold outside, the batteries are low, the starter and cables are a little iffy. Any one of these can cause trouble, and it's common to have two or more of these on top of each other. I consider ether a troubleshooting tool.
I have never been able to jump these engines off another vehicle. The other vehicle will help, but if the batteries are dead I have never been able to glow the plugs long enough and crank it to get it to go.