More people should ask this question.
I put the pump in a vice and spin it with a socket using a 1/2" variable speed drill to get a visual of it's operation.
Rig up a small fuel system with 1/4" tubing (clear), fuel filter on the suction side, and the return side going
back into the fuel jar or whatever.
When you spin the pump, you'll see how it moves fuel and primes itself.
If that goes well, connect a 12v DC power supply to the fuel solenoid. It should make an audible click when it gets power.
Now, put something to catch fuel at the delivery valves. With power to the pump, when you spin it fuel should spit out of
the delivery valves. If you work the throttle while spinning the pump you should see fuel quantity increase.
One thing I've noticed is that it sometimes takes a while for the fuel to start spitting out of a pump that has been sitting.
Doing this really helps get the pump ready to run. Compared to priming with the engine starter, a drill spins the pump much faster.
Not doing this can lead to a lot of long engine cranking which is very hard on the starter and battery.
But most of all, it's good to see that the pump primes itself and injects fuel before doing all that work of installing.
Btw, the fuel was dark in my because I had filled the pump with powerservice dieselKleen additive for storage.