FAQ-51

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Thompson's Auto Repair and Towing Mesa Arizona

My car dies, stalls or loses power while I'm driving.

When a car dies and stalls or loses power while under power, it has to be related to the absence of fuel or spark. Here's a couple of questions you can answer that will help the shop find and fix your problem:

What happens if you floor the accelerator? If the engine dies quicker, that would indicate a lack of fuel.

Do you ever see black smoke coming from the tailpipe, if so when? This typically indicates the abundance of fuel or the lack of spark. Backfiring with black tailpipe smoke means the spark just came back, backfiring with no black smoke means a lean condition or the absence of fuel.

When it dies, does it start right back up? If so, that usually means the problem is electrical 'cause the absence of fuel typically creates the need to crank the car longer until the fuel system re-primes its self.

If it won't start right back up, if you let it sit for 5 minutes, will it now start? This usually indicates a bad fuel pump.

Does the amount of fuel in your gas tank have anything to do with the frequency of the problem? If the problem happens much more often with the fuel tank at or near 1/4 as opposed to the problem happening far less when the tank is over 3/4, that points directly to the fuel pump, IF it is located in the tank.

Last but not least, if the engine dies and won't restart, the driver can help the shop a lot if they are "willing to be taught how" to quickly determine what is missing, fuel or spark. The driver can be taught how to use an old spark plug to test for spark. You can be taught how to spray carb cleaner into the air filter area in an effort to see if an alternate source of fuel will allow the engine to start and run for a second or two until it uses up the fuel sprayed into the air cleaner. This would show fuel starvation as the problem.

If the problem is simply the engine loses power, a plugged catalytic converter can also cause that problem. A shop can test the cat by drilling a small 1/4 hole in the pipe just in front of and behind the cat. With the engine in park, raise the rpms to 2,000 and feel the air or exhaust coming out of both holes. Is exhaust coming out of the front hole at a higher speed and at a larger volume than the rear hole? If there is an obvious difference of pressure between the two drilled holes, the cat is plugged and needs to be replaced. If you decide to do your own test, you can close up the two drilled holes afterwards either by having someone weld them up ($10-20) or simply screwing a big sheet metal screw into the hole.

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