My parents’ car is a '99 Ford Taurus. The first time they go to start it in the morning, it either won’t start or has some trouble starting. If it doesn’t start, they can go back out a little later and it starts fine. Either way, once it does start, it runs fine for the rest of the day, and can be started with no trouble at all. Then the next morning the cycle begins again. It’s been to the mechanic twice for this problem, but he can find nothing wrong with it. Any ideas what the problem could be? Btw, this problem has been happening in May and June, so cold weather is not responsible, it has been warm.
The next morning, instead of trying to start the engine, turn the ignition switch to the Run position so the dash lights come on for a couple seconds, and then turn the ignition switch to Off. Repeat this a half dozen times and then try starting the engine. If the engine starts right up there’s a problem with the check valve in the fuel pump assembly where it’s allowing the gas to leak back into the gas tank from the fuel rails on the engine as the vehicle sits overnight.
If this is the problem, you can live with it for a while by using the key On-Off method. But eventually the problem will get worse to the point where the fuel pump will require replacement.