Questions and Answers

Volkswagen Jetta Won't Start Hot Q. Hi, I have the above car and I am currently having problems with it starting it when it is hot outside, generally when it is out in the sun and is over 80° F. This has been happening for about the last three weeks, since the temperature has been warmer. The engine will turn over and it sounds like the fuel pump is pumping, but it just won't start.

Once it cools down later in the afternoon, the car will start right up. I had no problem with it starting in the winter and it will start right up when it is cloudy or below 80°. I previously had a problem with it shutting down while running, and I had it serviced and the mass air flow sensor was changed. Have you heard of this happening with other Volkswagens?

• 1994 Volkswagen Jetta GLS III
• 2.0 liter engine
• Automatic transmission
• Fuel injected DOHC
• 62,300 miles
• ABS, P/S, A/C, Cruise

Thanks,
Roy

A. Two possibilities come to mind in this situation. The first is that the baseline setting/adjustment on your Mass Air Flow sensor (MAF) is incorrect. This can cause an excessively rich fuel mixture which will flood the engine in warm weather. The second possibility is that the temperature sensor for the cold start injector is faulty, or the cold start injector is stuck open.

You can try disconnecting the electrical connector to your cold start injector and see if it starts while hot then. You may have to depress the gas pedal to the floor to clear a flooding condition for a little bit. If it still doesn't start, you can remove the cold start injector and reconnect the electrical connector.

Crank the engine over and observe whether or not it sprays fuel. If it does, disconnect the electrical connector again and try cranking. If it still sprays fuel the injector is faulty. If not, the problem most likely lies with your temperature sensor.