Starting problem when hot

There is a switch in the airflow meter that keeps the fuel pump relay closed as long as there is airflow. With the meter unplugged, the pump should not run except when the key is turned to start. It would seem to me that you have a wiring issue. Try jumping the fuel pump relay so the pump runs whenever the key is on. (Remove the relay and jump the pump wire to the accessory wire--see top left diagram.) This defeats the safety feature but will keep the pump running.

some times when the water pump is changed you gotta fill up the radiator with coolant, run the engine until it gets hot, shut off the car and wait until the car cools down to put more coolant because some air may stay trapped inside and by following this steps you get rid of the air trapped inside.
try this:
1) when the car is cool take the cap of the radiator off and see if it's full. if it isn't, with the car still off, put some coolant until it gets full.

2) once the radiator is full, start your car and wait to see if the coolant goes down the radiator. if it does, keep putting coolant until it doesn't take any more.

Hope to be useful.

it could be an electrical problem.. temperature sensors may tell the engine its getting too hot and wont let it start until its completely cool.. you may need the sensors changed because they are giving false readings.. but the best thing you could do is to take your car to your nearest garage soon in case it turns out to be a serious problem.

My 03 zr2 had similar problems. Mine was the fuel pressure regulator

Hi and welcome to FixYa!

As a first course of action, I strongly suggest that you replace the ignition coil. If the ignition coil gets hot the car may stall or may not start right away till it cools down. The ignition coil is surely faulty and replacement is surely necessary.

Hope this helps and thank you for using FixYa! Have a good one!

Check the electronics in the distributor. Chevs are notorious for the electronics going bad inside of the distributor.

Check the Mass airflo sensor, Mine went out and did not start. Check engine light shows air intake

If the vehicle was running hot it will continue to overheat until you locate a coolant leak and repair or replace the leaking part. It is critical you do not wait to repair this. You must first add water to your cooling system before you can troubleshoot the problem. Add the water while the vehicle is cooled down. If the vehicle is having trouble starting it is possible that you have allowed the engine to run hot too long. You could also have a head gasket leak from the motor. This could let coolant leak into the oil and you can check your oil and find a milky white substance that is a mix of coolant and oil. If that is the case you need to take the vehicle to a motor repair shop. To troubleshoot leaking cooling system get or borrow a cooling system leak check kit. It screws on in place of the radiator cap, you pump it up and use a flourescent light to then look in the engine compartment under the hood for a dripping green coolant leak. Good luck.

clean egr 'exaust gas return' intake channels and or clean maf 'mass air flow sensor'

replace the temp sensor in the thermostat housing behind alt(2 wires)