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2010 cranks but won't start

49K views 18 replies 10 participants last post by  Dalton124 
#1 ·
If car sits more than 6 hrs it will crank but not start. If the gas pedal it pushed to the floor it starts. If the car is warmed up it starts fine. Replaced purge valve and still same problem.
 
#4 ·
Thread moved from Gen8 to Gen7 section. Watch where you post.
 
#5 ·
When you push the pedal to the floor it goes into clear flood mood. So if it starts when you do this I would think that your car is flooding. Maybe bad FPR that is leaking when it sits, I know there was an issue like this with the impalas a few years back. You should be able to take the vacuum hose of the FPR while it's running and it might take a few minutes but if it is leaking you should smell or see fuel. But if it will start when you push the pedal to the floor I would be checking for things that would cause a flood situation.
 
#9 ·
Floored gas pedal to get it to start is a symptom of a leaky injector. Leak down test is the diagnosis for that. Fuel pressure gauge attached and seeing how long it holds pressure is the test. Don't know if there is a pressure port on your car though, someone more familiar will know that.
 
#10 ·
I just looked in the service manual and the 2.4 and 3.6 should have a service port schrader valve.

What is normal for time for the fuel pressure leak down test? Minutes or hours and how much of a drop is normal?

Is a leaky injector something that can be fixed with a good fuel injector cleaner(like what the dealers use) or do you just replace the injector?
 
#13 ·
My 2010 Malibu 2.4 is very similar. Cranks excessive, chugs to life due to flooding, P0172 code. No vacuum leaks detected. Downstream B1-S2 O2 sensor stuck around 700. Fuel pressure leaks down from 50 psi to about 40 in 15 minutes. Is this normal leak down time? Can O2 sensor cause flood on cold start only? I do appreciate any help.
 
#14 ·
Code is for rich condition.
Flood on cold start could be do to a faulty engine temperature sensor. You need to see what temp. ECT sensor is reading on a cold start via scan tool. Check inlet temp. also. PCM adjusts fuel richer for colder temps. so if PCM see's colder than what it actually is it could flood motor. Sensors can be off temp. and not set a code as most codes are for open or shorted.
Usually a leaky injector affects hot starts.
Is your battery in good shape? Weak battery will affect everything, especially on a cold start when battery is in a reduced power state.
 
#16 ·
Are you following proper starting procedure? Turn key to run for a few seconds then crank it over without stepping on the gas.
Can't help you on TSB.
Disconnect battery for a few minutes, touch cables together and then reconnect battery is the only field reset other than code reader reset I know of.
 
#17 ·
The dealer had to reprogram/relearn the computer to fix this exact issue (not starting on cold start, but running fine otherwise). My 2010 (80K miles) starts great now (before on a cold start I was having to put gas pedal to the floor), but I still have a P0172 code and the dealer doesn't know what the reason is. O'Reilly's Auto Parts scanner also detected a "U" code (not sure exactly which) that detected an issue with communication with BCM (BODY CONTROL MODULE). Any ideas on that would be appreciated.
 
#18 ·
As far as the BCM communication code read the fretting corrosion sticky in the index it may just be a matter of cleaning / reseating the BCM connector it's a common issue
 
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