Chevrolet: 00 SS Hard to start warm, fuel pressure guage, coolant temp

Question
Thanx for the advice ~ a couple follow on questions:  If the fuel pump is bad, would not demonstrate the problem after the car sat for a few days & the fuel drained back to the tank (over time)?  

What is the relationship w/ the coolant sensor?  Are we talking about the Temperature or level sensor? Something I noticed different on this Camaro vs. my 94 Z/28, is that on the 00 SS, the temperature gage slowly comes up to 210 F and it just stays there ~ when running its never cooler or hotter.

Thanx again for the advice ~ Also, I just got a recall notice from GM to replace the catalytic converters ~ could they be playing a part?

Mark
-------------------------------------------
The text above is a follow-up to ...

-----Question-----
I have a 2000 SS ~ LS1 w/51K, All stock w/ regular maintenance & Bosch +4 Plugs.  Here's the problem:  Starts fine cold, run for about 20 miles, stop.  Let sit for about 1/2 hour, and it will not start. Turns over fine, but will not start.  Changed fuel filter & ignition relays.  Snap-On code reader shows no codes.  If you restart right after you turn off, it starts right up.  Any ideas?  Had to tow home twice!!

Thanx

Mark
-----Answer-----
More than likely the check ball in the fuel pump is bad and allowing the fuel to slowly drain back into the tank. The next morning you try to start it do this. Turn the key on but don't crank the engine. Hold it there for 3 or 4 seconds and then turn it off. Do that cycling for 5 times and then after the fifth time, crank it up. If it starts fine then, you proved that's what it is. To fix it you would have to replace the fuel pump.

Open up the oil cap and see if you smell fuel.

Otherwise its a bad coolant sensor.

Answer
The coolant temp sensor tells the PCM how hot the car is running and will pull timing out.

There are two sensors, one in the head and one near the water pump. The one near the pump is usually the culprit.

Get a manual fuel pressure guage ($40)and connect it to your schraeder valve. Tape it to your windshield so u can see if the psi is slowly coming up or going down. It should be instantaneous and never come up slowly or go down slowly more than 2 psi.