Van dies in hot weather

I have a 1995 Ford Aerostar minivan with a 4.0L engine. It is an all wheel drive. When we are traveling on hot days (85-90+), then van will start to lose power and then die. After sitting for about 20-30 minutes, it starts up and runs fine for a while longer. When it is real hot, it keeps repeating over and over. It can be worse when we are towing our popup trailer with it. The engine runs like it is not getting any fuel. Any thoughts? Thanks!!

Do you have a temp gauge or warning light? First candidate for suspicion is the cooling system. Check coolant level, and have a pressure test on the cooling system. Has the coolant ever been flushed, changed checked? I think you have been lucky so far but there are some repairs in your near future.

Cooling system is good. Had it tested and flushed when I blew out a hose last summer. This issue has been ongoing for about 3 summers now. Engine is not over temp when it dies. Warning light on the dash is on all the time and a coupe of mechanics cant figure out why. No codes to read out.It only happens when the ambient air temperature is hot.

The problem might be caused from vapor lock. There’s going to be some who say that vapor lock can’t occur on a fuel injected engine, but that’s BS. I’ve seen vapor lock occur on FI engines. And the van you drive is a good candidate for a vapor lock problem because of how the engine is crammed under the hood, and where the fuel rails sit down in the valley of the inatake manifold. This area gets extremely hot as the engine operates. And here’s what happens.

As you drive, the fuel pump is delivering fuel to the fuel rails for the injectors. As this fuel sits in the fuel rails it gets heated up. But not all the fuel is used by the fuel injectors. That which isn’t used is returned back to the gas tank via the fuel pressure regulator. As this heated, unused gas is returned back to the gas tank it begins to heat up the gas in the gas tank. This cycle continues until the gas in the gas tank reaches a temperature where when it returns back to the heated fuel rails it then it becomes volotile. When this happens, the gas in the fuel rails begins to boil and you get vapor lock where the fuel pressure is lost and the engine loses power and stalls. If you allow the engine to sit for awhile, it cools down enough to where the vapor lock no longer exists. And the engine starts, runs until it gets hot enough again where the vapor lock reoccurs.

Now if you want to find out if this is what’s happening, it’s easy to do. The next time this occurs, open the hood, and take a bottle of water and pour it on the fuel rails. Now try starting the engine. If the engine starts, there’s a vapor lock issue.


Thanks for the tip. The engine dies and acts just like a vapor lock is happening. Is there a fix for this or do I just have to live with it? Thanks.