LH6 5.3 Stalled then cranks but will not start. Please help if you can.

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So I had just installed my LS2 style valley pan and catch can and drove my 06 trailblazer the day before. Everything went great after installing new coil packs, Moroso wires, new NGK plugs, flow matched and refurbished stock injectors and new valve cover seals as part of an earlier DOD delete where I installed a Bryan Tooley stage 2 V2 truck cam and replaced a bent rod.

I thought everything was great. The next morning it started right up better than ever before. I gave it a little gas pedal and it stalled. Then it would not start. I do not have spark on the only cylinder I tested. Fuel pressure at the rail is 58 lbs. static. I can smell fuel when it cranks. The spark plug looks fuel washed and hyper clean, no carbon whatsoever, but it is new. I will disconnect fuel pump relay for further testing.

Any ideas? I am currently learning HP Tuners software, so I am unsure what to do. FYI: I have an AEM wide band gauge installed, but it is not functioning correctly in my scanner yet, only my gauge face indicates what my AFR is. Thanks in advance.

[kevin87turbot]

Be sure to check all of the fuses. Make sure that the coil harnesses are connected properly. The grounds that go to the cylinder heads are critical on these engines. Make sure that they are tight and clean.

Are you getting an rpm signal during cranking?

[pannetron]

One set of coils I used would draw a LOT of current at zero and low RPM and blew the 10 AMP coil fuse. Reducing the zero RPM dwell numbers eliminated the blown fuse problem and the engine has started and run perfectly since then.

[blindsquirrel]

These trucks have underhood fuse/relay box issues. If everything checks out but still no power to stuff, look there. There are copper interconnects inside between separator layers and the copper gets brittle with age and cracks. Can be repaired with patience and care.

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Thanks! I will start with the grounds. I noticed the coil bracket is loose.

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Be sure to check all of the fuses. Make sure that the coil harnesses are connected properly. The grounds that go to the cylinder heads are critical on these engines. Make sure that they are tight and clean.

Are you getting an rpm signal during cranking?

yes I am getting rpms indicated at crank over.

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I will look the coil fuse up. Thank you.

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Good to know. Thank you.

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So yes I do get a tach signal on the hp scanner and fuel when turning the motor over. Any idea what I should do next?

[5FDP]

A log file could be helpful.

And for what it's worth I would turn off the VATS system too.

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07132021loglh6NOstart.hpl Here is my scanner log file, cranking, not running.

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I have turned off the VATS and created a log file, thank you!

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So I removed the VATS and still no start, I will be focusing on tracing why I have no spark. I do have a crank signal to the tach. So it is somewhere after that. I will check the new CPs and spark plugs. I did get some low voltage to the CPs, but I am not yet sure I know what I am looking for regarding the voltage and the 4 different wires. Being the vehicle died when adding throttle I will try to make sense of that.

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I got an P0521 code when I checked DTCs and that was supposed to be a oil pressure switch code. I took out the switch and cleaned it, then replaced it and tried starting to no avail. I then added some oil in case it was low (vehicle parked on a steep hill) No help. I then put the pressure switch back in and turned the engine over with no start then removed the pressure switch to have a look. I let her crank for 5 seconds. No oil on the switch at all, so I am getting worried. I believe this is causing my ?no start? issue. I am truly stumped. I am probably now on the wrong forum with this issue, thanks to all that helped me. I really appreciate your opinions and educated guesses.

[pannetron]

if it's truly a no oil pressure problem, the o-ring on the oil pickup tube may have split or slipped where it connects to the oil pump.

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I was thinking the same thing. After cranking it this morning with the sensor out it pushed a lot of oil out the sensor hole. I feel pretty good about the oil pressure now. Thank you. I will install a new oil pressure switch/sensor tomorrow and see if I can get spark to happen.

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SOLVED!! It was what most everyone thought. I traced the no start issue to one loose ground on the right side head (front) that visually looked tight but wasn?t at all. Thanks to this great site and everyone who gave me direction. You are all great!