I have a bit of a mind bender here and I’m hoping someone has seen or heard of this before. The issue started as a start and die, then no restart with a P2291 Low ICP while cranking code. We performed diagnostics and ultimately found air in the injector return lines. We found it by isolating the injector return from the pump return at the junction near the drivers rear of the engine and performing the balloon test. The balloon test was inconclusive, so I just ran a hose from the return into a container with water. When I cranked the engine bubbles were clearly visible. The injectors had some miles on them, so we recommended pulling all eight for testing and resealing or replacing as required. This is where it starts to get strange. When we removed the injectors there was no signs of combustion gasses blowing past the chamber gaskets into the injector bore. The injectors all tested ok. We resealed all the injectors and reinstalled them. When we attempted to start the engine it fired, then died, and would not restart. We ran back through the diagnostics and again isolated the issue to air in the return from the injectors. The only thing I could come up with at this point was maybe a cracked injector cup through the chamber gasket surface. We decided to try and isolate the cylinder where the problem was by removing one glow plug at a time, then cranking the engine and looking for air. We removed all eight glow plugs and still had air in the injector return. Strange, but after thinking about it, it made sense that there was still some pressure in the cylinder even though the glow plug was removed. So I figured maybe we could isolate the cylinder by using our leakage tester to apply pressure to one cylinder at a time to find the culprit. We did narrow it down to #3 cylinder. Bubbles were clearly visible when pressure was applied to the cylinder. We pulled the injector back out for inspection. Nothing was obvious, other than a spot in the chamber gasket seat in the sleeve that looked like it may be a crack. I pulled the sleeve out and it does not appear to be cracked through. We are now going to replace the sleeves, but needless to say my confidence isn’t high that the issue will be resolved. Have you heard of anything like this? Do you have any insight or ideas on what we may be missing? I would greatly appreciate your feedback.
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6.4 Powerstroke Air in Injector Return
- Thread starter Yotadzl
- Start date
what was rail pressure when cranking? Actual vs desired?
Any glitter in the upper fuel filter?
After it sits for a while it will build rail pressure and start briefly before dying. Then rail pressure will only build to around 300 psi. No metal in the filter or in the rails. It doesn't run long enough to get a good actual vs desired reading, but it builds and starts quickly when it decides to.
You can monitor those pids when cranking and get good data. Also, is the cap of the lpfp tightened to the plastic stop? I have seen slightly loose caps or damaged orings cause something similar.
I'm aware that you can, but it doesn't do me a lot of good because it builds normally after sitting for a while or being bled out well. Once started air is pumped into the upper filter housing through the injector return circuit. We did check for air coming from the HFCM and it was fine.