I'm working on a TCM FCG15-3L. It will crank but never turn over. I've changed spark plugs, tested cam & crank sensor plugs & they have power. So, I put new sensors in.... It has a new battery. When I disconnected the propane, there were vapors so it seems to be getting fuel. I also changed the LP regulator and drained the vaporizer plug. Anyone have any suggestions?? ECU has been tested, as well.