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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.
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.
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.
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.
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.
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.
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.
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.
Last edited by sinisterSF; 06-27-2016 at 07:15 PM.
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.
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
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?
06-26-2016, 11:18 PM
