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Alero wont cold start unless I use starting fluid

I have a 2002 Olds Alero 3.4, 140,000 miles. My issue is my car will crank and wont start. I initially thought it was a security issue so I had Milzy Motorsport remove the security out of my pcm and still no luck. However usually if I change a part like unplug a pcm and re-flash it then put it back in my car it will start right up, however if my car sits over night and gets cold it wont start, But if I shoot a little bit of starting fluid in there and crank it it’ll fire a bit and then crank it again it starts right up. So I have come to the conclusion the system needs primed to start but I cant seem to find out why. It makes good compression, spark is good and fuel pressure is 58psi and then after the pump primes for like 10 seconds it sits at 50psi waiting for the vehicle to start. I’m at a complete loss because I can get this thing start it drives around really well its still really fast and it’ll start when I turn it off until it sits for about 6 hours or however long it takes for the motor to completely cool off. Also I took this to a shop they had it for 8 weeks and gave up on it. So feel free to respond, seriously any help is much appreciated.

Have you tried the key dance: turn the key to Run, not all the way to Start. The fuel pump should run for a few seconds then turn off. In a quiet place you can probably hear it.Turn the key back to Off then to Run again and let the fuel pump run and turn off. Each key dance brings fuel and fuel pressure up to the engine. After a couple or more key dances, turn the key all the way to Start. What happens?

Leave the fuel pressure gauge on overnight. If the injectors are leaking down, the car will be harder to start. @shanonia’s suggestion is to identify this exact problem.

I’d also hook up an OBD 2 scanner to read the coolant and air temp sensors in real time as the car starts and warms up to see if the sensors are providing the correct signal. If the ECU doesn’t know it is cold, it won’t add extra fuel.

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Yes I have tried that, I also have tried a new Fuel Pressure Regulator and a Pump

Okay! Ill hook my laptop up to my pc and see! also dont be afraid to ask for a lot im no noob when it comes to cars but what mine is doing is something I have never seen before and obviously not many people considering a shop gave my car back to me :rofl:

You spray starting fluid into intake and car starts.
Shop says you have no fuel delivery issue.
Yep. Odd.
Good spark. Proper fuel pressure. Injectors are firing.
Fuel IS being sprayed into combustion chamber?

Yeah i’m so confused, my next guess is a coolant temperature sensor. It has been reading weird lately. When I have time i’m going to hook up my laptop and check to see what the car reads it at and then compare it to outside temp. But if the sensor thinks the engine is warm when its not it wont run a little rich to give it the ability to cold start so that may be the issue but doesn’t sound promising. I might go to a junk yard and pick up a whole new fuel system however I feel that’s not the case because my tune is running fine and when it starts it had no problem making 230hp. and no the tune is not the issue I guarantee it a %100

By “my tune” do you mean modifications? If so, what? And can you restore it to original?

My 3.4 makes 180hp. Does a tune on a non turbo motor really give you 50 more hp?

No an actual tune I had done and a few mod that I have reversed to trouble shoot

Well I know its not the coolant temperature sensor. anybody have ideas?

My car has been doing the same thing since I got it I’m thinking just keep it plugged in overnight so it does start cuz my Pontiac does the same thing 2 but only during the winter

It sounds like your driving my 02 Alero 3.4l
I have done the same things you have done and even thought of doing by changing out the complete fuel system so don’t waist your time or money it doesn’t change anything.
Now before I had this car it was my buddy’s daughters and I had it running for her after a no start issue by swapping out the fuel pump and it ran great for two years. Then they came back with another no start but it wasn’t the pump and but I got it running and it was all good and that’s when I learned that the starter fluid was the pre-day process and they didn’t want to deal with it anymore and sold me the car. Well after playing around with every wire under the hood I did it no more pre-day spay it would start no matter what time or not or cold again nothing was replaced and I was happy and then almost a year to the day it went back to the pre-day spray then grow to if it sat longer then 6 hours now it’s down to 4 I have redone everything I did before with no luck. And now I’m starting to believe it’s is an issue with the crank sensor from a post I had read somewhere else just recently. I believe when I got lucky it was do to messing with that harness in the past so when the money allows I’ll change the sinsor and possibly the harness because the last thing it could be if that doesn’t work is it’s just far enough out of time maybe to not cold start if that is possible. But if you get to try this crank sensor theary before I do let me know how it goes and I’ll do the same
Good luck