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Hoping there is someone out there that can help:) The truck does not start on first attempt 1/2 the time but always will start on second attempt. Runs great after starting. The fuel injectors are not getting enabled (grounded). Checked with noid light. Problem is not fuel or spark related. Fuel pump replaced, cam sensor replaced, I even replaced ECM. It could be passlock 2 security issue but I am getting no security light flashing, no codes and I did the resistor bypass trick just to take that our of equation. I am getting frustrated. I read that crank position sensor has some bearing on ECM pulsing injectors but truck runs fine once started so not sure replacing that makes sense. Can anyone help? Different key turn techniques do not have any impact on problem
 

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I had an issue with my pass lock. It hated one of the two keys. Then one day it just wouldn’t start. I pulled the battery and left it over night. Next day started fine with no issues. Never had a problem since. I don’t know what the cause was or why pulling the battery fixed it. Oh wait. I think I ended up having to replace a battery cable or power cable shortly after that. Maybe that fixed it. I wish I could be more helpful. It was many years ago.
 

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Not a passlock or crank position sensor problem. Sounds more like a fuel problem to me and not electrical.
Have you checked the fuel pressure at first key on (not started) ? Pump will run for 2 seconds and pressure should be 55-62 PSI. It should not bleed off more than 5 PSI after 1 minute of key on. The reason I ask is because you are actually enabling the fuel pump twice to start the truck by turning the key to start twice. If the fuel pressure is low on first key on position then it will require a second key on to bring it up to proper pressure. You could have a leaking fuel injector that drops fuel pressure before first start or maybe even a pressure regulator problem.
 

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Hi, thanks for your reply. I changed the crank position sensor today , did not help. This all started when the fuel pump went out when I was out of town. Had to have non oem pump installed. I began to notice the "often does not start on first crank issue". I assumed this was a defective fuel pump, I had the shop order AC Delco pump and swapped it. We were all shocked when this did not solve problem. Mechanic spent a few hours on this. Checked pressure and that was fine, no drop at all swapped fuel pressure regulator, checked filter and finally isolated with a noid light that fuel injectors not being pulsed when it would not start. That was got me thinking it was security related but now not so sure.
 

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Not a passlock or crank position sensor problem. Sounds more like a fuel problem to me and not electrical.
Have you checked the fuel pressure at first key on (not started) ? Pump will run for 2 seconds and pressure should be 55-62 PSI. It should not bleed off more than 5 PSI after 1 minute of key on. The reason I ask is because you are actually enabling the fuel pump twice to start the truck by turning the key to start twice. If the fuel pressure is low on first key on position then it will require a second key on to bring it up to proper pressure. You could have a leaking fuel injector that drops fuel pressure before first start or maybe even a pressure regulator problem.
Hi,

Well I wanted to check fuel injectors myself so I bought a noid light. Plugged it into an injector and when the engine did not start it did in fact have a blinking light, blinked a bit slowly compared to when running but that seems normal. So maybe I have been chasing the wrong thing. This problem started (I believe) when the fuel pump went out when I was out of town. Had to have non oem pump installed. I began to notice the "often does not start on first crank issue". I assumed this was a defective fuel pump, I had the shop order AC Delco pump and swapped it. We were all shocked when this did not solve problem. Mechanic spent a few hours on this. Checked pressure and that was fine, no drop at all he said and even swapped fuel pressure regulator, checked fuel filter and finally isolated with a noid light that fuel injectors not being pulsed when it would not start. Well I am seeing something different, measured 12v and now I see noid light flashing when does not start.
 

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Hi,

Well I wanted to check fuel injectors myself so I bought a noid light. Plugged it into an injector and when the engine did not start it did in fact have a blinking light, blinked a bit slowly compared to when running but that seems normal. So maybe I have been chasing the wrong thing. This problem started (I believe) when the fuel pump went out when I was out of town. Had to have non oem pump installed. I began to notice the "often does not start on first crank issue". I assumed this was a defective fuel pump, I had the shop order AC Delco pump and swapped it. We were all shocked when this did not solve problem. Mechanic spent a few hours on this. Checked pressure and that was fine, no drop at all he said and even swapped fuel pressure regulator, checked fuel filter and finally isolated with a noid light that fuel injectors not being pulsed when it would not start. Well I am seeing something different, measured 12v and now I see noid light flashing when does not start.
The weird thing is that sometimes it will be sitting for a while and start. Sometimes it will be running, I will shut off and then not start. You would think it there was a fuel pressure leak it would be more predictable
 

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I had a semi similar problem with a 99 Suburban I had with the 7.4 liter. When it sat for a longtime it would fire right up. If I started it not too long after shutting it off it would fire right up. But if I tried to start it after just sitting for a short while it wouldn’t crank on the first turn. But would on the second. That turned out to be two a leaky injectors.
 

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What would happen is when it had trouble cranking is a puff of dark smoke would come out. Mechanic said injectors leaked gas into cylinders almost like flooding them. But only two. Not all.
 

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What would happen is when it had trouble cranking is a puff of dark smoke would come out. Mechanic said injectors leaked gas into cylinders almost like flooding them. But only two. Not all.
Interesting, sometimes if I let it crank it will pop slightly. I am dropping off to have it looked at tommorrow. Thanks
 
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