My car is usually parked in a garage. When I start the car in there on really hot days it starts up right away.

Ive noticed that when the car is sitting out in the sun, on a really hot day, when I start the car, I have to hold the key down for bout 4 seconds till it kicks in. Why is that? Only happens outdoors on those scorching hot days.

 

On a very hot day, when the fuel pump shuts down, the heat from the engine compartment and exhaust can cause the fuel in the lines and rails to vaporize... causing a brief "vapor lock" until the liquid fuel refills the system. This may be more noticeable if your fuel pressure is dropping off very quickly when the pump shuts down.

Check your fuel pressure when turning the key to "on", before trying to start the engine.

 

Thanx for the detailed explanation! I will give it a shot the next time it's hot out.

 

I never really corrected this problem as I dont drive all that much. Still have the same problem. I turned the key to "on" back and forth 3 times and the car started up right away after that. Should I change the fuel pump?

 

You want to check the fuel pressure to see if the pump or pressure regulator is the cause. They are around $25-$35 and are a good idea to own.