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


Asked by May 20, 2013 at 06:46 PM about the 1986 Mercury Grand Marquis

Question type: Maintenance & Repair

Only has problem in warm temperatures.1986 Mercury Grand Marquis 5.0 has a problem starting. After it is warmed up and turned off for 10 to 15 minutes fuel punp operates but, no fuel to engine. Car will eventually start after a few more minutes. Car has new fuel punp and filter with full tank of gas or less. What can possibly be wrong?

10 Answers

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.

1 out of 1 people think this is helpful.

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

1 out of 1 people think this is helpful.

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~

Michael Tutty

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.

2 out of 2 people think this is helpful.

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.

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