It reads like you are turning it off when you let go of the starter position on the key. If that is the case then ignition switch alignment might be the cure. Just to be sure there are a couple of work around you can do to test.
The pink wire on the top of the injection pump is the power lead that lets the engine run and turns it off when power is removed. The CUCV has 12 volts at that connection with the key on. Using a test light, volt meter, power probe or whatever you want. See what you have with the key on. If nothing, follow the pink wire back toward the steering column and find out why not.
If you do, figure out a way to monitor the voltage when you let go of the starter.
Or if you don’t want to do any test and just see if it runs. Connect a jumper wire between the front battery positI’ve and the pink wire connection at the injection pump. Make sure you are using the front battery and only have 12 volts. Go through the glow plug cycle and hit the starter. If that is your problem it should run just fine.
