1991 Lumina 3.1L hard starting hot

I have a 1991 Lumina Euro 3.1 that starts and runs great when it's cold. If you warm it up and shut it off for 5+ minutes, then it will crank over and try to start but
stall. Does this about 3 times before it finally starts and the RPMs go up to 2000 for a few seconds before slowly settling back down.
If you shut the car off and immediately start it back up it starts fine. It also runs fine all the time once it starts. Not sure how long it needs to sit, but once it sits overnight it always starts right up the next day.
Any ideas? It's giving no service codes(none that I can get anyway). Thanks in advance.
Chris
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pull the vacuum hose off the fuel press. reg. on the rail, see if there is fuel in it. If it leaks it will cause hard star after short soaks. This one of many possibilities

If you warm it up and shut it off for

up to 2000 for a few seconds before slowly settling back down.

It also runs fine all the time once it starts.

starts right up the next day.

Thanks in advance.

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my first guess is the fuel pressure regulator is slowly leaking down.. when it sits for 5 to 10 minutes, it fills up the wrong side of the regulator(vacuum line side), and even fills the line up a little... if it sits overnight, it probably evaporates, or in a cold start, it probably likes the extra shot of fuel anyways... but on a hot start, the fuel kinda makes it cough and stall a few times... not to mention that if you loose fuel pressure with a hot engine, the fuel in the rail boils and fills the lines with air making you start it multiple times to force the air out...do you have a fuel gauge with the quick connect needed??? Bobo

If you warm it up and shut it off for

up to 2000 for a few seconds before slowly settling back down.

It also runs fine all the time once it starts.

starts right up the next day.

Thanks in advance.

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Thanks for the replies. I had done some research and came across this as well, but didn't understand why. Makes sense now. Unfortunately, I do not have a guage and connector. Can I disconnect the vacuum line and check for leakage(as Dave suggested)? Is it a big job to replace the regulator?
Thanks again
Chris
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I pulled the vacuum line after warming it up and shutting if off. After about a minute, fuel started to drip. Sounds like it's the pressure regulator.
Thanks again for the help!
Chris
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