1986 mercury grand marquis 5.0 has a problem starting.What can possibly be wrong?

you must get your diagnostic trouble codes read, have manny moe or jack come out and scan the car, or do it yourself with your own scanner-

Thanks, will have to wait until it isn't starting in the drive way.

no check engine light?

No check lites. Engine cranks, fuel pump works but no fuel to engine. Outside temperature 85 degrees. Drove home earlier, turned car off and waited 5 seconds, car started easily. Half hour later the car wouldn't start. Fuel pump working but, no fuel to engine. Five minutes later car starts easily.

it is temperature related...no...therefore am going to suggest an ambient air temperature sensor....yes they exist~

Thanks, I'll check it out. Will get back when I'm sure of the solution.

if it has fuel injection it need to know the ambient temperature, if it is a carb, there is heat-riser and stove-kit~

You have the fuel injected 302 in this car. If the pump is kicking in, but no gas is reaching the engine, there are 2 things I can think of. The first is vapor lock. It is uncommon, but if the fuel line has been replaced, and not routed properly, it can happen that the gas boils off. The second is a defective regulator. It may be closing under certain temperature conditions.

Thanks, I will post when I find an answer.

Have you solved your problem? I have pretty much the same problem, but mine acts like yours in hot or cold weather.

Guys we had bad fuel in our area..water in fuel lines.flush tank or add fuel system cleaner

These grand marquis have a reset button in the back of the trunk. Grand Marquis are equipped that when they have an impact of some type, for example a huge pump on the street or an impact with another car. The fuel pump will shut off so that it impedes the fuel to run. These is so that the fuel does not leak and cause a fire or the car to explode. Maybe there is something there that you might want to look at.