Not necessarily, just because they are working when manually firing them
doesn't mean they are working when cranking. There should be a connector
somewhere between the fuel injectors and the computer. It will have the same
number of leads as there are injectors. These are the control wires for the
injectors, you have to make sure you have the right one. Unplug it, stick a
test light to the battery positive (+) and one of the leads on the computer
side. Have a friend crank the engine over and watch the test light, is it
flashing? If so, maybe the injectors are clogged, if not, something else is
wrong. Usually if an engine managment switch/sensor goes bad, the check
engine light will be illuminated.

Again, you have to let us know if the check engine light is on, which engine
you have and the year/mileage of the vehicle to get proper help.

Steve