I have been chasing an itermittent miss or fishbite I have seen it called for quite a while now. In my attempt to chase it down I have good fuel pressure from the pump and I replaced the filter to the optical sensor at Heath diesels advice, but it didn't get rid of it. So the past couple days I have been watching for air coming out of the return from the injector pump. There is nothing most of the time, but during a long 12 mile pull up to the ski area today I accumulated a bunch of miniscule bubbles. They were just tiny little guys. I never saw them again on the way down or around town so it would seem that it is only under a load that it appears. I was checking here for some sign of a possible faulty injector pump since the factory manual simply states to replace the pump if there is air in the return. So I guess my question is how much air is too much? Has anyone else had this be the cause of the infamous fishbite? 137,000 miles on the rig. I have only owned it for the last 17,000 miles and been chasing this miss since. So not sure how many miles are on the injectors, but this is air in the lines directly out of the pump. Very little air. Any ideas. Thanks