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Message: [QUOTE="Tiha, post: 1564770, member: 33189"] The injectors are not supposed to have any return flow, or at least very little. Which was odd because since I had a no start I figured one would be dumping fuel like crazy. Or I was hoping one was. On top of that, the injectors need back pressure to operate properly. So the test really is not accurate except to try and find a no start injector failure. I pulled the injectors and took them to a diesel shop that ran them on their high dollar bosch machine. At the point where I was, it had to be injectors or pump causing my no start. I was not getting enough information or instruction on how to test the injectors any farther than I had. Honestly I could not find anyone else that had tried to do a return flow test so I had no idea if I did it right. But I did. Same with the pump. Not enough information out there. I think it is $25 or $50 an injector to run them on the stand and test them. Can't remember for sure. On the high dollar bosch machine I had one injector that was not responding to computer control within limits. 3 others that were marginal. So even though they were not causing my no start 4 of them failed test and should be replaced. I have the test paperwork loaded up in my other thread. I would imagine you take just about any 6.7 out there with over 100k miles and pull the injectors and run them on the test stand you will find a couple that are not working like they did when they were new. In comparison the new injectors, I have one that has fuel trims twice what my original set was. I guess that doesn't mean it isn't working properly but still strange. That also means that fuel trims are not a great indicator of a bad injector either. I don't know the science behind it. But I think the return line is more about purging air from the fuel system rather than an injector actually needing to return fuel. [/QUOTE]