Ray, not knowing which grill you have there are a few things to try. Start by turning 1 or two burners on low and see what temps you can maintain. on my weber three burner, one burner on low holds about 275 to 300. Then get a disposable pie pan or something similar and place some chips or chunks in it , I have found chunks work better on mine. Lift the grill and place the pan on burner.it should start smoking once hot.
place your grill back on and see how long it smokes. You may have to cover pie pan with foil and put a few holes in foil to keep it from flaming up. A few holes is all that is needed. using this method I am able to get about thirty to forty five minutes of smoke per pie pan full of chunks. I have to lift the grill cover from time to time to maintain temp, its a royal PITA but it works. you going to have to experiment to see what works best on the grill you have. Good luck, let us know what happens.