Z31 cold start/fuel system question

[BBISHOPPCM]

My 87 non-turbo won't stay running when started in 40 below weather unless I keep my foot on the accelerator for a few seconds. Once I do this, it runs a bit rough until it reaches operating temperature. I recently replaced the fuel pressure regulator due to a faulty fuel temp sensor (this neither helped nor worsened the problem). I noticed that by disconnecting the vacuum line to the pressure regulator it idles smoother... my question is this; is the fuel pressure regulator vacuum solenoid supposed to be open or closed when the engine is cold and idling, and when is it supposed to close?

[evildky]

holy crap 40 below!? I'd suggest moving to some place warmer!

not sure on the vac but I'd look at the IAC and have you checked the computer for codes?

[BBISHOPPCM]

Yes, it was throwing a code for the faulty fuel temp sensor, and replacing the sensor (and clearing the code) did not fix the problem. The computer is not throwing any codes at this time.

[evildky]

heh, maybe the sensor is sending out signals so cold the ecu can't believe it

[BBISHOPPCM]

Whoops! I meant 40 degrees...

[StephenR]

I was wondering if and how you resolved this... I seem to be having a very similar problem.

Thanks!

-Steve

[BBISHOPPCM]

Yes, the problem was resolved when the ambient temperature rose to above 40 degrees (I kid you not). The real problem lies within the cold start valve. My workaround was to hold the accelerator down slightly for a few seconds.