need help on my first LS conversion,04 LQ9 in an 86 K5, no start

Big Red, although I've checked all grounds several times. I must have yanked one out of the crimp the other day when I dropped the passenger side downpipe. Reconnected ground and now have injectors firing. Allen was right, something happened that was coincidental to the learn procedure. After repairing ground, still wouldn't crank. Got desperate and gave it blast of either down the tb. Fired right up for 2 or 3 seconds and sounded good like timing and everything was right except it ran out of fuel. I think I either have water in the fuel or the octane has just evaporated cause the back end of the truck has been sitting out in this 100 degree heat and sun for a couple of months.
I'm going to drain the lines and tank and put some fresh fuel in. If that doesn't do it, I'll have injectors checked, but when I pulled the fuel rail and touched them with 12v, they all were spraying the fuel left in the fuel rail.

What do you guys think? Again, thanks for all the help.

It's not bad fuel, if it was, it would at least try to start...pop fart belch.

Either you have no fuel to the rail or the PCM is not allowing fuel injection. I think it's the latter.

ok, I got it, if the motor has spark and you give it a straight shot of either, it doesn't care whether the injectors are firing or not. So what does the pcm see or not see that would keep it from firing the injectors? I got to excited when I heard it run, need to go back and verify injectors are firing with noid light. BTW, the other pcm does the same thing.

Scan tool says no codes, but is flashing o2 sensor heater.

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Originally Posted by stevebbc

Scan tool says no codes, but is flashing o2 sensor heater.

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What does that mean? Do you have any kind of scanner? If so, can you see cranking RPM? If not, ask Greg about pinching the harness. If so, you need to re-verify power to pink wires to injectors. If that's OK, connect the test light to power and probe the non-pink wire at a disconnected injector and look for it to flash while cranking (not always a valid test because of the impedance difference in most test lights and most injectors).

I rented what I thought was a tool the would read live data from Oreillys but it has no instructions and appears to be just a fancy looking code reader. Can't find any menus that would read cranking rpm. I have good voltage on the pink wires during cranking and in run. I will try noid lights again to verify.

Allen, went straight off battery to power pink wires on the injectors, still not lighting noid light.

did you verify the two grounds are good on the pcm?

yep, many times. grounds are going to Blue1, Blue40, Red1,Red40. Power B20 – Battery + all the time
B57 – Battery + all the time
B75 – off/run/crank

A bad cam sensor or wiring to it or even a cam swap to an incompatible cam where the sensor pickup point isnt there will all cause the injectors to not fire.

Already changed cam and crank sensor and ohm out wires when I did so. Guess I could check again.

Checked cam sensor wiring again, I have 12v with key on and cranking, signal wire ohmed out ok. Reinstalled oem sensor. Same problem. What other things would the pcm be checking off that would cause it to shut down fuel?

did you check and ohm out the wires to the crank sensor behind the starter? Flex the wires around by the connector down there, I've seen them break internally and work intermittently. Other than that it's pretty much VATS keeping things from going.