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2007 Mazda 6 has trouble starting in hot weather

Hello all,

I have a 2007 Mazda 6, 4 cylinder, abt 30k miles. I bought it new in May 2007 and began having a somewhat obnoxious problem starting April/May 2009.

If I let the car sit all day in the sun (or possibly just with hot temps), the car will fail to start. I turn the key a little bit and I get electrical power and can open the windows, run the fan, play music, etc. I turn the key farther to start the ignition process and hear the first part of the startup (a sputtering sort of sound) as long as I keep the key turned - but the engine fails to start.

I’ve tried to fix and workaround this problem, but it persists and is obnoxious. Here’s additional information.

The problem doesn’t occur if the dash thermometer reads about 82 deg F or below (the dash thermometer doesn’t really report ambient temperatures correctly and reads high temperatures after sitting in the sun). I’m guessing the threshold temp for this to occur is 83 or 84 deg F.

If I put my fan on high for 3 to 10 minutes, I can almost always get the car started eventually. 3 mins is if the temperature is lower. Today the car temperature reading was 92 degrees and it took 7 mins of running the fan before I could successfully start the car.

I’ve tried using fuel line cleaner with no success. Still happens on empty and full gas tanks.

The battery failed a load test and has been replaced very recently.

I’ve taken the car to the dealer, but they haven’t been able to duplicate the problem (presumably because once whatever cools off, it takes quite a while to heat up again). So, under cool temperatures, this problem is impossible to find with whatever current diagnostics techniques mazda dealers use.

My current suspicion is something causing vapor lock, such as dirty fuel filters, a defective fuel pump or fuel injector, or faulty electronics.

Anybody have an idea what is wrong?


well i’m not an expert but if running the fan helps then explore that. do you mean the radiator fan or the cabin fan? if it’s the radiator fan then i think you may have a vapor lock issue. you could try parking in the shade…i live in Houston (where it’s hot) and i go by an area where hundreds of cabbies wait by the airport for a fare. i notice that most of them open their hoods while waiting…i assume to avoid vapor lock. if you are parking somewhere reasonably safe you might consider popping the hood and leaving it slightly open when you park.

hopefully some of the more technically inclined readers will have a permanent fix. i’ve had no starting problems even in temps over 100 degrees but i do have the six rather than the 4.

Did you ever find a solution to your problem??? I have an 07 mazda 6 and have the same exact problem. I have been dealing with it for about 2 months off and on and no one can seem to fix it. The dealer couldn’t fix it for me either. Hopefully you get this even though it’s 2 years after your original post. Thanks.