03 Sierra 6.0l starting issue

ktraver97ss

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So the past few weeks I have been noticing every like 5 starts it takes a few tries to start. About a week ago the starter went out, I replaced and hoped that would fix it but its still happening. Could this be an issue with some teeth on the flywheel?

What else could it be?
 

Yaj Yak

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silly question but how's your battery
 

rdsnake

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Check both battery terminals. GMs are famous for corroded terminals with side post
 

ktraver97ss

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Threw a fresh one in there when i did the starter and it did the same thing, so i returned it. lol It doesnt do it like after sitting all night or anything. It could be after driving for a few minutes or 20, doesnt seem to matter.
 

RICH17

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Check cables. at both ends, And batter ground
 

10sec

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So during the 5 starts it's spinning the starter and not the motor?
 

Euro

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It's probably because TCG thinks it doesn't exist, because you never post any pictures :mamoru:
 

ktraver97ss

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So during the 5 starts it's spinning the starter and not the motor?
Well I never counted exactly in between, but it will start perfectly fine like 3 to 6 times and then once is will struggle for a second or 2 and it will sound like its not going to start, but it always does, never had to retry it. If I shut it down and start again it will start right up without the hesitation.
 

10sec

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Well I never counted exactly in between, but it will start perfectly fine like 3 to 6 times and then once is will struggle for a second or 2 and it will sound like its not going to start, but it always does, never had to retry it. If I shut it down and start again it will start right up without the hesitation.
I still don't get what you're saying. Is the ENGINE spinning whilst you're trying to start it?
 

Yaj Yak

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SAY WHILST ONE MORE TIME
 

Dasfinc

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Intermittent hard start on two separate vehicles I've owned were the result of Crank Position Sensors being flaky (V-8 Ranger, and the All-Road).

No idea how common that is on LS motors, but I can't imagine that's an expensive sensor.
 

The Bluegrass Nomad

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Sounds silly, but based on the little information provided, it could be the gas tank evap valve. I had thos issue on my 99 silvy 6.0 and once it was replaced, started fine every time.
 

OffshoreDrilling

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crank sensor, tps sensor

any other issues or quirks while it's running?
 

ktraver97ss

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I still don't get what you're saying. Is the ENGINE spinning whilst you're trying to start it?
Not sure, seems like it is, just maybe not as hard and fast as it should be to get it to start right up.
 

ktraver97ss

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Sounds silly, but based on the little information provided, it could be the gas tank evap valve. I had thos issue on my 99 silvy 6.0 and once it was replaced, started fine every time.
hmmmm that could be it, it would throw the evap code every now and then a while back but it went away on its own so I never did anything. I bet thats it, Ill replace it and see what happens.

crank sensor, tps sensor

any other issues or quirks while it's running?
Not really, drives normally. I need to check that evap valve.
 

Dasfinc

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hmmmm that could be it, it would throw the evap code every now and then a while back but it went away on its own so I never did anything. I bet thats it, Ill replace it and see what happens.



Not really, drives normally. I need to check that evap valve.
Crank sensor being 'flaky' doesn't really cause Driveability issues for many motors IIRC.
 

bikrboy128

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so the engine is cranking but it's just not firing up?
usually a sensor failure will set a code.

IMO fuel pumps are the most common chevy truck failure. yours is probably on it's way out. do you have a fuel pressure gauge? they are cheap at harbor freight, maybe pick one up and have it in the truck. when it's not starting hook it up to the fuel rail and see what the pressure is.
 

P40E

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So the past few weeks I have been noticing every like 5 starts it takes a few tries to start. About a week ago the starter went out, I replaced and hoped that would fix it but its still happening. Could this be an issue with some teeth on the flywheel?

What else could it be?
I have read this thread and you are still not being descriptive enough to give an online opinion of what the cause may be .

What I get from your post is that it's is hard to start sometimes. You replaced the starter and it is still the same . Then you go on to ask about the flywheel .

Are you asking about Flex plate because it is grinding when cranking ?

You say it happens randomly . When it happens , does the starter sound really bad when trying to start or grinding noise ? Or does it just crank slow like a half dead battery ?

Or does the cranking sound normal , but just doesn't start ?
 

P40E

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so the engine is cranking but it's just not firing up?
usually a sensor failure will set a code.

IMO fuel pumps are the most common chevy truck failure. yours is probably on it's way out. do you have a fuel pressure gauge? they are cheap at harbor freight, maybe pick one up and have it in the truck. when it's not starting hook it up to the fuel rail and see what the pressure is.
Gm truck fuel pumps from that era were bad but had different symptoms per vehicle . My Yukon pump would start fine , then fail after warmed up . After a while it couldn't maintain pressure at all , and it would only start normally and maintain idle . Any load on the pedal and the truck would stumble bad and eventually die out .
 

ktraver97ss

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so the engine is cranking but it's just not firing up?
usually a sensor failure will set a code.

IMO fuel pumps are the most common chevy truck failure. yours is probably on it's way out. do you have a fuel pressure gauge? they are cheap at harbor freight, maybe pick one up and have it in the truck. when it's not starting hook it up to the fuel rail and see what the pressure is.
Yep, it cranks but slower than normal, and just doesn't fire up right away, takes it a second as if I didnt turn the key fully, but I did. No codes now, but like I mentioned I was getting that evap code earlier this year but have not seen it pop for several months now.

That could be possible as it seems it does it less often if I turn the key to on for a couple seconds and let it prime. Might be time for a walbro and fresh filter. But then Ill end up pulling the bed and going buck wild with por15 under der.

I have read this thread and you are still not being descriptive enough to give an online opinion of what the cause may be .

What I get from your post is that it's is hard to start sometimes. You replaced the starter and it is still the same . Then you go on to ask about the flywheel .

Are you asking about Flex plate because it is grinding when cranking ?

You say it happens randomly . When it happens , does the starter sound really bad when trying to start or grinding noise ? Or does it just crank slow like a half dead battery ?

Or does the cranking sound normal , but just doesn't start ?
Yes, like I said, it struggles to fire up right away sometimes, like every 5 or so starts. The starter died completely, thats why I replaced it. I assumed the starting issue was due to it being on its way out, but that was not the case as it continues to do it with the new starter. Flywheel, flexplate, same difference, no? I mean yes, its an auto so yeah the flexplate, which has the starter gear on it. I mentioned it cause I don't know whats causing this issue, Im not a mechanic. Im capable of taking apart and putting shit back together but I hate diagnosing problems. lol

No crazy grinding noises or anything like that, just slow like the battery is weak, but it did it with the new battery also so unless I got unlucky and that battery was shitty too I didnt think that was the issue.
 

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