Cold morning.... Crank but no start.

[Retroman1969]

Yeah, may never happen again, who knows.
If I had to make an uneducated guess: Fuel pump getting weak, fuel regulator has slight leak, water in fuel.....
There has been no check engine light, so I'm going to assume it's not something like an O2 sensor.
The last time it got that cold, the car ran very rough until it warmed up, so there is definitely something about the temp getting below 20 degrees overnight that isn't agreeing with the car.

KRAM: I'm wondering if your sound is your fuel pump? Especially since you first noticed it after the car acted up for the first time.

[jdlmodelt]

Mine has done that too. If you don't let it run for a few minutes and shut it down too soon it will do it. If it has been setting for a week or two it has done it. I find that I have to push the gas pedal all the way down and hold it there while I crank until it starts. They flood and stall and then don't want to start.

[Retroman1969]

Originally Posted by jdlmodelt

Mine has done that too. If you don't let it run for a few minutes and shut it down too soon it will do it. If it has been setting for a week or two it has done it. I find that I have to push the gas pedal all the way down and hold it there while I crank until it starts. They flood and stall and then don't want to start.

Yes, it was holding the pedal down that eventually got it started. I'm guessing the big puff of smoke is further evidence it was flooding (it's not the AOS, I had it checked recently).
I've never driven my other Boxster in sub freezing temps, so I don't know if these engines are prone to flooding in such weather (beyond being programmed to give a richer mixture for cold starts) or if it's the failure of a part.
Thanks for the extra input.

[KRAM36]

Originally Posted by Retroman1969

Yeah, may never happen again, who knows.
If I had to make an uneducated guess: Fuel pump getting weak, fuel regulator has slight leak, water in fuel.....
There has been no check engine light, so I'm going to assume it's not something like an O2 sensor.
The last time it got that cold, the car ran very rough until it warmed up, so there is definitely something about the temp getting below 20 degrees overnight that isn't agreeing with the car.

KRAM: I'm wondering if your sound is your fuel pump? Especially since you first noticed it after the car acted up for the first time.

The pump noise I hear is just like when you first start up the car. You will here a slight pump noise then it goes away. I'll pull up to a stop sign and hear that exact same noise. Not every time I stop, but occasionally I hear it.

[thstone]

Originally Posted by KRAM36

The pump noise I hear is just like when you first start up the car. You will here a slight pump noise then it goes away. I'll pull up to a stop sign and hear that exact same noise. Not every time I stop, but occasionally I hear it.

That is the secondary air injection (SAI) pump testing the integrity of the system. The SAI system is part of the emissions package so the ECU commands a test each time the car is started. This usually happens at the first red light or stop sign that you come to.

To execute the test, all of the SAI system valves are commanded closed and the SAI pump is commanded on for several seconds. The system measures the pressure increase thereby validating that the SAI pump is working and that the system does not have any pressure leaks. If the ECU does not receive the pressure increase signal, the ECU will set an SAI error code and illuminate the CEL on the dash.

[woodsman]

A common cause of cold-start problems is water in the fuel tank. Water collects over time (years) and sits on the bottom of the tank (where the pump pick up is). Once below freezing ice forms and blocks the fuel until it's saturated. In climates used to cold weather fuel line antifreeze is used as well as products that eliminate the water. On some vehicles I've owned I used to occasionally fun them down to fumes to get rid of this but doing that in a Boxster will probably cook your fuel pump...