Check for a blown fuse. We have found the 5 Amps useful with ¼ teaspoon of Electrolyte for 1 quart of water. For high HHO production we use 1½ teaspoon of Electrolyte to 1 quart of water, and replace the fuse to 8-10 Amps (although idling current measurement reads around 3 Amps).
If the fuse is OK, check the wiring. Measure the voltage between the terminals – it should read around 12 Volts (usually 13.8 Volts when the engine is on). If you don’t have a voltmeter, check with any 12-volt bulb.
Fuse keeps blowing? First check the wiring outside the device. Verify that nothing touches the body of the car or some other metallic or conductive element. Inspect the electrodes inside the device. I've been asked if they should be touching each other. Well yes and no.
Sometimes there are two wires in each electrode, sometimes only one. Each electrode, which is the wire, or pair of wires, coming out of negative or positive terminal (the bolt with the wingnut) and spiraling down, should be in one piece (i.e., not broken or visibly damaged) and spiraling at intervals of about 3/8” from the other electrode. If the electrodes are too close, separate them as shown and glue in place with Plumbers Goop. If an electrode is made up of more than one wire, its wires can be touching or not touching, as long as none of the wires are too close to the wires in the opposite electrode. The grooved tower is an excellent solution to prevent the electrodes from touching - without glue (see DVD 2 for instructions).