Dear Car Talk:

I have a car-repair problem that three local shops can't fix. My 1996 Toyota Tacoma (two-wheel drive, 2.4-liter engine) won't start after it's been running and the air temperature is 80 degrees or higher. It cranks fine, but won't catch. I have to let it cool down for several hours, and then it starts normally. A tuneup didn't help. This has been going on for three summers, and is getting more consistent. Any ideas, so I can tell the repair shops what to replace? -- Tom

Well, my first idea is to stop telling the shops what to replace. I assume you were the one who told them to try a tuneup. Most mechanics would know that a tuneup would never fix this particular problem. The most useful thing you can do, Tom, is reproduce the problem for them.

Since it happens only after it's been running for a while in hot weather, you're going to have to wait for a hot day -- a hot weekday -- when they're open. Then take the truck out for a long drive, and drive right into the entrance of the shop -- so you're blocking the exit. Then shut off the engine.

Once it's misbehaving for them, they'll be able to perform some crucial tests and approach it in a logical way. For instance, they can pull off a spark-plug wire and see if it's making spark. If it's not, they know you've got an ignition problem -- and they can test for a bad coil, a bad igniter or perhaps something like a crank angle sensor.

If the truck is making a spark, then they'll know you've got a fuel problem, and they can test your fuel pump and fuel pump relay.

And if they approach it logically and systematically like that, they'll figure out which part is actually faulty, replace it, the truck will start up for them, and your problem will be solved. And then you can deal with the angry mob of customers you blocked in, Tom. Good luck.