So my thinking is that fuel injector #4 is failing. Is there a way to test it before I replace it? And if I have to "drain the fuel" already in the fuel injector manifold thing how do I do that so it's not leaking fuel all over and not so messy? The next step is to create the lighting circuit. This will involve connecting the battery to the LED light and then connecting the LED light to the switch. Use a breadboard and jumper wires to create the circuit diagram. I also spilled antifreeze on my speed and reference sensors when doing the heater core. Could that cause something to go bad?

Never force your noid light into the harness or into the fuel injector clip. This should easily slide into position and create a firm connection for you to test. Never use a noid light that’s intended for a different vehicle, and always exercise safety around your engine bay.Next, connect the free ends of the wires to the appropriate terminals within the fuel injector connector, ensuring proper polarity. Secure the connections with solder or crimp connectors, and insulate them with heat shrink tubing or electrical tape. Your homemade noid light is now ready for use. To test a fuel injector, plug the noid light into the vehicle’s injector harness and observe the LED while the engine is cranked. The LED should flash if the electrical signal from the ECM is functioning correctly. Why Make Your Own Noid Light

When creating the circuit, use positive (+) and negative (-) terminals on the battery and LED light. Also, make sure that the switch is in the “off” position before connecting the battery. Step 3: Complete the Circuit: Making a homemade noid light is easy, and requires minimal materials. The basic items you need are a 12-volt bulb, a wire, and a male and female electrical connector. Not sure how I had any spark coming out of this thing at all. It must've burned up the last bit of copper when I was testing ... this was the last thing I thought of because the previous owner told me he had replaced all of the ignition parts just before I bought the thing a little over a year ago. The fuel injector Noid light kit that I recommend is the Performance Tool W89501 10-Piece Noid and IAC Light Set, and here some reasons why:This is one of the most complete Noid light kits on the market. It contains Noid lights for the different fuel injector connectors used on the majority of makes and models, since not all cars use the same fuel injector connector type. Now your vehicle will be much more visible while driving at night, and you’ll be the envy of all your friends! So get out there and make some noid lights for everyone!