Starts fine when cold; increasingly difficult to start when hot – sometimes has to sit half an hour. Main fuel relay is not the problem. New plugs from the dealer. Any fire/fuel test done when cold is obviously going to be irrelevant. Could it be something as simple as water in the gasoline? Surely temperature isn’t going to effect something like a fuel filter? Do fuel injectors go bad? About 90,000 miles on this 1990 model.
Distributors go bad. Almost all of the ignition system is inside the distributor. This web site covers the problem rather thoroughly: It’s a good site for other makes of cars / trucks, also. http://www.tegger.com/hondafaq/startproblems.html I re-entered this url. I hope it works, now. Your mechanic could find some pertinent pointers there. There are several components to check out, not just the ignition module.
For others puzzled by this, here is the diagnosis a friend of mine just gave me: “It might be an ignition module. To test for that, when it gets hot and won’t start or run, pull the coil wire from the distributor cap and crank engine to see if you are getting a strong blue spark approximately a quarter inch long to a ground such as the engine block or head. You may get an orange spark which will be too weak to run the engine. You can also use a spark plug wire for testing but it requires inserting a metal rod up inside the plug wire to test for a spark. A screw driver with an insulated handle so that you won’t get shocked while testing. I’ve seen many ignition modules fail after they heat up.”
You’re not going to believe what this turned out to be – merely a vapor lock in the fuel tank. Factory cap got lost, replaced with a generic that apparently doesn’t allow as much breathing. Moved to a warmer climate and, wa-la, vapor lock. Loosening the cap to let the pressure off solves the problem now. Oh well, only $168 for the ignition module which probably would have gone bad eventually anyway.
It’s of interest as to how this was discovered? Was there a check engine light code? Was there a moment of serendipity, or what?