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Upside down injector trick is overrated
I keep seeing guys on here swear by the upside down injector trick for priming a new common rail system but I tried it last week on a 6.7 Cummins in my shop near Tulsa and it didnt help at all. Ended up with air in the rail for 2 hours before I got it sorted. What actually worked was cracking the high pressure lines at the injectors and cranking it for 20 seconds at a time until fuel dribbled out. Took 3 rounds of that and she fired right up. The upside down thing just made a mess and wasted my time. Has anyone else had better luck with just cracking lines instead of that trick?
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ray_martinez821mo ago
Cracking the lines is the real way to do it. That upside down nonsense is just internet hype that makes a mess. Air purges out way faster with a little fuel dribble.
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sean_cooper581mo ago
Ray nailed it with "air purges out way faster with a little fuel dribble" - that's exactly what I found too. I tried that upside down injector trick on a 6.7 Powerstroke last month and it was a complete waste of time and fuel. Made a mess all over the intake and still had air in the rail. Cracking the lines at the injectors and cranking it over in short bursts got it done in about 10 minutes. Took maybe 4 rounds of 15 seconds each but she fired up smooth after that. I swear half the guys pushing that upside down thing have never actually worked on a modern common rail system before. @ray_martinez82 is absolutely right, the old school way works when you need it to.
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