Sometimes it takes two attempts to start my car after it has been parked for several hours. What's wrong?

Honda Sam is correct.

The fuel system pressure is leaking down.

1) Could be the fuel pressure regulator.

2) Could be the check valve in the fuel pump.

3) The real question is why the fuel pump isn't re-pressurizing the system when you turn the key on.

Try turning the key to the 'on' position and listen for the fuel pump to run for a couple of seconds then shut off. If you cannot or do not hear it, check the fuel pump relay.

You can have someone turn the key while you check that the relay picks up when they turn the key on. If it does not pick-up, change the relay, they are less than $10.

Again; it should pick-up and then stop after a couple of seconds, this circuit pressurizes the fuel system prior to start.

4) The fuel pump will run without the relay, when the oil pressure reaches 4-6psi the oil pressure sensor will start the fuel pump. The starter turning the motor will provide this much oil pressure. So, if you have noticed the car has to be cranked a while, then starts, the problem is most likely the fuel pump relay or that circuit.

5) First thing is to turn the key to "on" for a couple of seconds before you continue to the "start" position with the key.

Yours" Susan

Actually, Susan's answer covers it pretty good.

Check the Fuel Pump relay. Even if it is picking up the contacts can be bad.

Buy a relay and replace the one you have, if it fixes the problem throw the old one away. If the problem persists you have a spare.

My Bet , it is the the relay.

when was the last time you changed your fuel filter? It is a fuel problem, you might possible have a small fuel leak in the fuel system that makes the system loose pressure when parked for long periods. So the engine has to crank longer to re pressure the fuel system again. You wouldn't have a problem starting after 15 min. because the system is still holding pressure for that short period of time.

Read Susan's answer:

Just change the Fuel Pump relay. Go to Auto-zone or your favorite auto parts store and tell them you need a fuel pump relay for your Mustang.

If you don't know where it is , ask them to show you, it just unplugs and you stick in the new one.

initiate with the gasoline device the gasoline clear out then the different issues like the gasoline rigidity sensor initiate much less costly you do no longer decide to spend money that's no longer had to be spent i'd would desire to declare the gasoline clear out if that hasn't been replaced

check your car battery...it could be due to the battery as when you left the car for several hours...the battery is getting flat, so you find it hard to start your engine....but as soon as your car's moving, the battery will be automatically recharged by the alternator and you will find it easier to start after that or after leaving it off for shorter period like for 15 minutes....

have your engine timed and have them replace your spark plugs if necessary. have them check your timing belt, too.

car just doesnt seem to like cold starts. could be lotsa things. could be anything from lubricant problems to starter motor.

You could have alittle dirt in your gas line.It won't get any better if you don't have it check out.Hope this helps.

Clowmy

its either the battery or ur u need a new starter