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2009 Cobalt SS Cranks a While, Fires, then Dies Immediately.

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Old 06-26-2016 | 11:18 PM
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2009 Cobalt SS Cranks a While, Fires, then Dies Immediately.

Hi guys,
So I picked up a 09 SS with 90k on it today and it's not running. I'm just trying to do a little self diagnosis before I break down and take it in to a shop. I charged up the battery and started giving it some cranks.

First off, is it normal that the thing keeps cranking after you let off the key and the clutch is still pushed in?

After a few short attempts and cranking I decided to crank the hell out of it for about 15-20 seconds. It was cranking kind of slow, then it started to speed up and eventually it fired for about a second then died. I repeated that a few times, it fires but won't keep running.

Perhaps a dead fuel pump? How do i check the fuel pressure on this thing?

It's not giving me any codes, but it did have a dead battery for months, they may not have populated yet since I just charged it.

Any ideas?
Old 06-26-2016 | 11:53 PM
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Sounds like a fuel issue. Have you tried spraying a little starting fluid in the intake and seeing if it starts? There's a test port on the fuel rail for a fuel pressure gauge.

Which engine?

Yes it's normal for it to keep cranking until you turn the key off or release the clutch pedal. The PCM tries to fire the starter until the engine rpms come up, it will crank for a very long time if you let it.

Are you seeing the tach move when it cranks?
Old 06-27-2016 | 12:00 AM
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Originally Posted by ItalianJoe1
Sounds like a fuel issue. Have you tried spraying a little starting fluid in the intake and seeing if it starts? There's a test port on the fuel rail for a fuel pressure gauge.

Which engine?

Yes it's normal for it to keep cranking until you turn the key off or release the clutch pedal. The PCM tries to fire the starter until the engine rpms come up, it will crank for a very long time if you let it.

Are you seeing the tach move when it cranks?
I haven't tried starter fluid, the way it fires then dies seems like a starvation problem, I didn't want to cause any intake backfires with starter fluid. I'll borrow a fuel test set from autozone tomorrow and try to find this test port on the rail.

It's a 2.0 LNF turbo motor. The tach is moving while it cranks.
Old 06-27-2016 | 12:03 AM
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Oh if it's an LNF there may not be a port, as the injector rail is high pressure. Check for fuel pressure coming to the HPFP, if not then change the in tank pump. If you do have pressure, use a scanner to look at the rail pressure, you should have 1000+psi when cranking. If not change the HPFP.
Old 06-27-2016 | 12:08 AM
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Do I just disconnect the low pressure line from the HPFP and crank it to test it the tank pump is working?
Old 06-27-2016 | 12:11 AM
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NM, I see the schrader valve on the low pressure line. Much cleaner!
Old 06-27-2016 | 12:15 AM
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There ya go lol

You should have immediate 50+ psi in that line when you turn the key on. If not there's a pump/regulator issue. I haven't seen many fail on the LNF but lots of the earlier cars had problems, so anything is possible.

If you've got pressure there, try to start the car on outside fuel through the intake and see what happens. If it seems to start up ok on added fuel I'd assume your HPFP has died, they do fail from time to time.
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Old 06-27-2016 | 12:17 AM
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Cool, thanks. I'll try that stuff out tomorrow and post an update.
Old 06-27-2016 | 08:11 AM
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No codes pending or setting off a check engine light?

Also, have you ever checked compression on the engine?
Old 06-27-2016 | 08:28 AM
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Originally Posted by umrdyldo
No codes pending or setting off a check engine light?

Also, have you ever checked compression on the engine?
No codes yet, but it's had a dead battery for a while so it'll need to cycle some to pick up errors I imagine.

This morning I put gas in it, was close to empty. Cranked it a bunch and eventually it fires and dies. So I floored it once it starts and it revs up, bogs completely and dies.

I've not tested cylinder pressure yet. I'm going to go through the fuel system first. I rented a fuel pressure test kit this morning so I'll test the low side this afternoon.

How do I test the high pressure side? Not sure that this autozone kit can test it.
Old 06-27-2016 | 09:03 AM
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Originally Posted by sinisterSF
No codes yet, but it's had a dead battery for a while so it'll need to cycle some to pick up errors I imagine.

This morning I put gas in it, was close to empty. Cranked it a bunch and eventually it fires and dies. So I floored it once it starts and it revs up, bogs completely and dies.

I've not tested cylinder pressure yet. I'm going to go through the fuel system first. I rented a fuel pressure test kit this morning so I'll test the low side this afternoon.

How do I test the high pressure side? Not sure that this autozone kit can test it.
The easiest way as far as i know is to get a good scanner like HPTuners or even a basic bluetooth scanner with Torque App. The computer has a read out for the high pressure side and you should be able to log it during start up.
Old 06-27-2016 | 12:22 PM
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I don't have a HPtuner, perhaps I'll scoop up a bluetooth scanner today and try out torque
Old 06-27-2016 | 06:52 PM
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I tested the low pressure pump, 65psi, all good there. I put a voltmeter to the wires coming to the hpfp, got juice. Then I did an ohms test on the pump, nothing. If I touch the two pronges shouldn't I see a reaction on the ohms setting?

I tried squirting in some starter fluid but I'm not sure where to do it on this thing. No easy access near the throttle body.

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Old 06-27-2016 | 07:16 PM
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Here's a video of what's going on. For the first 3 crank cycles I didn't touch the pedal, all of the rest I depressed the pedal about an inch.
Old 06-27-2016 | 08:24 PM
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That sounds like it's got weak compression... have you tested it?
Old 06-27-2016 | 08:25 PM
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Originally Posted by ItalianJoe1
That sounds like it's got weak compression... have you tested it?
Nope, doing that next. If it's weak compression most likely busted rings?
Old 06-27-2016 | 08:28 PM
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Hard to say, that's not really a common failure on an LNF as much as it was on the LSJ. Could be a timing issue that bent valves.
Old 06-27-2016 | 10:02 PM
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Sooooooooo. i pull the plugs and immediately I know there's nothing wrong with the fuel. The plugs are black, wet, and smell like gas. Ut-oh.... So I proceed to compression test, 1=65 and doesn't hold it, 2,3,4 completely dead. So I think I know why it won't run now!

The oil is unmixed so I don't think it's a head gasket. Perhaps the rings, I'm gonna pull the head tomorrow and look for any obvious valve damage.

Any suggestions? Not sure if I'll rebuild or just buy an LDK motor from ZZP.
Old 06-27-2016 | 10:12 PM
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What would the motor be doing if the timing chain was broke? Just spit balling possible problems.
Old 06-27-2016 | 11:10 PM
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Slapping pistons on valves, unless you got super lucky and both cams are parked with the valves closed.

Another thing is to check for excessive intake valve coking, it could possibly but not probably prevent the intake valve from sealing.
Old 06-27-2016 | 11:18 PM
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Originally Posted by ECaulk
Slapping pistons on valves, unless you got super lucky and both cams are parked with the valves closed.

Another thing is to check for excessive intake valve coking, it could possibly but not probably prevent the intake valve from sealing.
Is there anything else I should check or test before I pull the head off?
Old 06-27-2016 | 11:26 PM
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Look at the intake side after removing the intake manifold from the head. Post a pic of it on here. If it's nasty and gunked up you might be lucky and just have coked intake runners. No need to pull the head to see it, you could also check the timing chain to make sure there is some tension, it's hydrolic so it won't be super tight
Old 06-27-2016 | 11:59 PM
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Yeah I didn't think it was fuel once I heard it cranking. You can tell it has no compression.
Old 06-28-2016 | 08:35 AM
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I took the intake off this morning, tons of buildup on the valves, but I don't think it would prevent them from closing.







Then I removed the valve cover (that oil return line on the turbo is a real bitch!). Timing chain has tension and I see no obvious valve train damage. Can I do any further checks from here or does the head need to come off now?

Old 06-28-2016 | 08:54 AM
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Those valves are just about the worst I have seen. Powell has probably seen worse.

I bet none of the valves are closing.

But as with a lot of ecotecs, unless you can find a cheap head, a new engine is sometimes a better idea.


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