L33 no start
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Teching In
Joined: Nov 2023
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L33 no start I've rebuilt the 5.3 in my 2009 sierra, and it didn't make oil pressure upon startup. I pulled the engine again, replaced the oil pickup (old one was clogged) and put it back together and back in. Upon start, the engine starts for a few seconds and high idle, then drops and dies. Very similar to not having the throttle body plugged in. This was very strange as it had no problem starting the first time the engine was in and not making oil pressure. Checked the codes and found oil pressure sensor code (non vvt, so oil pressure must be higher than normal tripping the code?) And cam sensor codes. I replaced the cam sensor which was a delightful experience in and of itself, and the same problem and codes remained...
These type of issues end up with a loose ground, or a connector not plugged in tight enough. The devil is in the details most of the time. Re-check everything. Twice. Three times.
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Teching In
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update: got it to start and stay running. contrary to last time, it wanted the MAFS plugged in this time. still zero oil pressure, and maybe even heard the lifters making a little noise because of that? What's going on here??? am I not priming something? I've primed the oil pump, poured oil in the sensor hole, new oil pump, pickup tube, radiator
Thread Starter
Teching In
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I've also gone back through my photos and realized the barbell plug wasn't replaced, but it's still in the block. is there a chance this plug has failed somehow? would it seriously cause oil pressure to be this bad? I figure it would only be this bad if the galley plug was missing.
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TECH Senior Member
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Pinched oil pump oil ring? It’s always best to “prime” an engine until you get oil out of ALL of the push rods. I don’t get people who buy a new engine or have one built and cheap out doing it GMs method.
Best of luck
Best of luck
Thread Starter
Teching In
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I recall the pump O ring seating well in the pump. the second time I've had it on as well. I've spent combined minutes cranking her over with no pressure indicated on the gauge. time to buy mechanical I guess... should I prime the new oil cooler in any way?