GMC Terrain 2.4 crank but no start
I recently removed rebuilt and replaced the 2.4 DI engine on this Terrain. After completing the install the engine refused to fire and run. Verified fuel pressure to the HP pump and pressure at the rail. It does turn over with a very rare "thump/grunt" of combustion. Decided to spray carb clean through the PCV hose port on inlet air duct to see if could get more combustion events. To my surprise, not only did I get more thumps, I actually got the engine to start! Rough for about 10 seconds then smoothed out. I let run for only 30 seconds total because I didn't have adequate amount coolant in system. Next morning I topped of coolant and restarted. It was a long crank cycle but fired and ran smoothly. The long crank time caused MIL for crankshaft position sensor relearn, which I expected after an engine rebuild. I allowed the engine to run for about 40 minutes while I cleaned up garage and inspected for any leaks of coolant or oil. I found no issue. Also scanned an saw no new codes from ECM. I decided to perform the relearn procedure for sensor. When I got to the step involving turning ignition off then back on, I could not restart the engine. That has been my situation since. Fuel pressure at rail is 2300+ with fuel pressure to the HP pump at 67 PSI. Both are the desired amounts. The fuel injectors were removed, cleaned, flowed, and all seals replaced and reinstalled.
I have an OTC Evolve scan tool and used it to perform the automated systems test to all modes and sensors. All passed. I have replaced the crankshaft position sensor in case it giving false data, but no change.
I can watch RPM, fuel pressures, injector duty, ignition voltage, etc and all look strong.
I am up for any help. I'm desperate and confused. This engine ran so smoothly for 40 minutes and not since.
At this point I am willing to change headlight fluid, muffler bearings, change tire pressure. 😀😀😀🤔🤔 60a;
Las Vegas NV
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Repair GM cars & SUVs