I tried to have gas service turned on but they told me I had a leak. The technician couldn't find it. He said I have to have it fixed before we can get service. Can the leak be found without gas running in the line?

Yes. You have to call a plumber who will disconnect gas meter and all gas appliances in your house. He will then plug all outlets and installs pressure gauge on one end. Then he will pressurize the line to 10 lbs for 10 minutes with compressed air to determine there is a leak. If pressure drops, there is a leak and he has to start looking for it. Usually, leaks are outside and under ground, like in BBQ line or gas line going to the pool heater. He may try to disconnect both, and re-pressurize the house only to see if pressure continues to drop. If not, than he knows the leak is in one of those two lines. He can disconnect them at the gas meter, cap them off and Gas Co. will turn your gas service ON. If the leak is somewhere inside the house than it is more difficult to find. There is a chance walls and maybe even ceilings may be cut to repair the leak.

Hope that helps

Milo