A couple of things that might help:
-
You can use hardware grade Mineral spirits for testing. It is very close to Stoddard solvent which is the industry standard for fuel system testing (not for every test but for 90% of the testing). Any error you might see between the Mineral spirits and gas is likely to be below your ability to measure.
-
Unless this is going to be a short test, injectors like to see a full voltage pulse to open then a reduced current to stay open. see the below driver.