I have an American/ Detroit 3/8" injector. It is picking up water ok but it is blowing it out the overflow. When I try to throttle the intake down it quits picking up. I am able to remove the injector and blow air through to where it enters the boiler. Steam pressure 70#. I have tested for air leaks on the intake side. I have had the injector apart several times.everything appears to be clean, all holes are open. I have limited experience with injectors. I've been reading about troubleshooting but can't seem to find an answer.