The crack in the distributor cap may be small enough not to be very visible
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Couple questions. How long ago was this? Also, who has checked it? Professional mechanic?

If a professional mechanic has not checked it, that's my first suggestion. If they have, I'd suggest taking it to another shop, because this one isn't doing a good job.

You may also try the "Car Talk" guys on NPR. I don't know how hard it is to get through to them but it could help. Their number is Call 1-888-CAR-TALK (888-227-8255)

Here's a Popular Mechanics blog answer about a car that doesn't start in the rain:

http://www.popularmechanics.com/blogs/automotive_clinic/4202330.html
Source(s):
http://www.cartalk.com/menus/show.html

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Backfiring after something like that sounds like one or more cylinders aren't firing. My guess is that there is still water in the D-cap, or possibly some corrosion that built up along a wire connector from the water. Take a peek at the boots over your plugs looking for corrosion(this also has the added benifit of making sure they are on good and didn't get shook loose). Then take a look in the d-cap and make absolute sure there is no water in there.
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An often overlooked problem is the automatic fuel-shutoff valve. Most cars made in the past 20 years detect a colision and automatically trigger a fuel shutoff valve to prevent fires. What can happen is that valve sometimes can get overly sensitive. I've seen cases where driving over a pothole has either partially or fully triggered it. There is usually a reset switch located in one of the taillight panels on the inside of the trunk (most commonly on the same side as where the gas cap is located). Check it and reset if necessary.
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If the car stalls and runs bad or won't restart after hitting a puddle, it's likely that water splashed all the way up to the distributor or coil, and is causing excessive arcing until it dries out. If the distributor is mounted at the front of the engine, it really should have a plastic shield over it. If getting out of the car and drying off the ignition parts with your T-shirt fixes the problem, you know the solution is replace or shield those components, or avoid puddles from now on - without causing an accident.
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I'd tend to suspect ignition as well, so make sure there is spark before moving on. If it that checks out, check for fuel pressure next. Probably OK, but that is the #2 thing to verify before you go on. If Fuel pressure is also OK, there may be a mechanical problem with the motor. (I will skip testing the injector system to verify fuel delivery for now.)

If the puddle was big enough, the engine could have actually ingested enough water to hydrolock and bend a valve, rod, crank, or crack something. Take a look at the air filter and see if it is soaking wet, or if there is evidence of water in the intake system. If so, good chance that happened.

The best way to check for sure is to run a compression check. Buy or borrow a tool that threads into the spark plug holes to do so. Some auto parts stores have free tool loan programs.

Compression tester:

http://www.sears.com/shc/s/p_10153_12605_00902171000P?vName=Automotive&cName=Tools&Equipment&sName=Automotive%20Testing%20Equipment&psid=FROOGLE01&sid=IDx20070921x00003a

Fuel Pressure Tester:
http://www.sears.com/shc/s/p_10153_12605_00902169000P?vName=Automotive&cName=Tools&Equipment&sName=Automotive%20Testing%20Equipment&psid=FROOGLE01&sid=IDx20070921x00003a
Source(s):
Experience.

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The water could have damaged the mass airflow sensor. I had one go bad on my 1998 Ford Explorer and it was hard to start and would backfire and stall easily. According to an article I found, you can't clean the MAF on your vehicle, it would need to be replaced.
Source(s):
http://autorepair.about.com/library/a/1d/bl827d.htm

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How big was this puddle? Did it cover the exhaust pipe? Did he stop in it and get stuck? If so, I would check for a gasket problem or piston ring issue from too much back pressure from the water blocking the exhaust pipe. Or, you may have got water in your gas tank somehow due to the incident, try and additive first but you may need to drain and refill your car to get it back in order.

If you can not start the car and keep it running try starting fluid and spray it into the intake to keep it the car running. If it works and you stop spraying it and it dies then it is a fuel issue.

If not check the timing, see how off it is, if you can keep it running long enough. You may have a faulty cam position sensor, or even your timing belt may have slipped out of position. This would cause backfiring. Backfiring is a timing issue almost all of the time, but poor fuel can cause backfiring too.

Hope this helps.
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First, check the battery voltage. Some modern cars will not properly fire their spark plug if the battery voltage is too low. A short somewhere may cause this by slowly discharging the battery. Hook up a booster charger and watch the amp load and voltage. As the voltage goes up, the amp load should taper off to essentially zero.

Then, try this: get a timing light, preferably an induction pickup unit, as the in line kind won't work on many modern vehicles. Attach the light to each plug wire in succession and see if you get any spark at all. If the light flashes rhythmically or semi-rhythmically (timing lights may 'miss' when the plug is firing correctly), move to the next plug. If you are getting good spark on all plugs, look for the timing mark. At this point, you ought to go down to Auto Zone or your local favorite parts store and buy a manual for the vehicle. If the timing is correct, then you have a compression problem. Compression meters are readily available. You screw them into the spark plug hole and crank the engine over to see what the pressure is.

The information you gave me leads me to think that you have some spark or the car would not produce enough heat to backfire, you have some compression or there would be little exhaust flow, and some of the valves, at least, are working correctly. The backfiring indicates fuel flow.

To tell you the truth, my favorite right now is the plug wires or the plug itself. Either can develop cracks. Modern ignition systems don't need to short to quit working; they just need to get the capacitance screwed up. Unfortunately, the best way to test for that problem is also a pretty stupid idea, so do not do this unless you are absolutely certain you know what you're doing, but the easiest test is to pull each plug in succession, lay it against the engine block, step way back and have someone turn the engine over. If there's no spark, the plug or wire is bad.

Heck, plugs and wires are so cheap you can just replace them all for little money, and, on an older car, it's a good idea anyway. Just make sure to get the appropriate wires and plugs for the car, which is not always the most expensive set.

Hmm. I believe that vehicle is actually a Mazda under the skin. If so, the plug wires go deep into the top of the engine, in a sort of well in the valve cover. It is *very* easy for water to get in there. Pull the plug wire boots and inspect them for moisture. When you replace them, use canned air or an air compressor to thoroughly blow the well out *before* you replace the plug as you do *not* want that stuff in your engine. As I said before, replacing the plugs is not expensive, and whether you do or not, when you put the boot back in, put a little of the spark boot grease around the flange at the top to reduce the odds of moisture getting in there in the future.

I used to own a Mercury Mystique that never ran right until I replaced all the plugs and wires with good, high quality ones. All the plugs and wires checked as good before I replaced them, but the Mazda ignition system is very high voltage and easily develops problems that may not show up when you are testing it.
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