How to test your injector and NOT burn it up. You are here because you are doing a balance test or have a dead injector. Check the ohms of the coil if it is open,  it is bad, no need to read further. Do not ever try this with a TBI 8 valve 1 ohm injector.  Never. IT WILL BURN UP INSTANTLY. The 16valve 4 port , 16valve injectors (12 ohms (about) are not designed for full 12vdc or even 14.7vdc (running ) full power to the injector continously. All injectors are PULSED, and are never run at STATIC voltages ever. A static 12vdc  will burn up the coil inside. (or damage it and weaken it, and will fail soon ) If you are too cheap to buy an injector pulser. then try these  methods.  ( the brave and fat wallets ) If you are reading this page (not for 1989-9'8 OLD cars) and your car has 5vdc injectors you need to wake up, and not blow up your 5vdc injectors. sorry. Consider Power,  as in WATTS.  MATH AND OHMS laws. I = V / R  or   12 / 12  , 12volts divided by 12 ohms , the current is 1 amp. One amp times 12 volts is 12 watts.  ( almost half the power of your 30 watt soldering pencil  , lots of heat in such a small area of the coil) The BRAVE: 1: USE a 9Vdc dry cell battery . (doing so reduces the voltage to near 5vdc and saves the injector, due to 9v battery overload at 0.75 amps !) it will be less really, as  the overload goes to 5v and current to 0.4amps , in fact, the injector may fail at 5vdc too.  making the test useless. 2: Use 12vdc only for 1 second.   (use a push button) resting 30 seconds then repeat. (may people do it, with success, but I don't)  I use the correct tools. (my pulser) 3: Never test any injector dry, best is in the car with the rail fuel flowing inside this cools the injector coils, and it may survive your torture. Don't blame me, I didn't design the injectors (fuel cooled injectors)  designed for pulse width  modulation. Did you know your ECU  even modulates them in a special way to keep them cool?   that is a FACT. They use the inertia of the coil slug to cut power  and cool it down then re=apply power to compelete the INJECTION. Google PWM  injector signals. that is the way it works. hint 2, don't forget to pull the injector filter cages and clean them first.