sacii

I have tried searching for this problem in this forum, but have not found anything on point.

When I start my Honda, I always turn the key to the second on position and wait until I hear the fuel pump run and pressurize the fuel line before turning the key to the start position. Usually, the fuel line pressurization begins about 1 second after turning the key to the second on position. However, since the middle of December, sometimes the fuel pump does not begin pressurizing the fuel line for anywhere from 30 seconds to more than 30 minutes.

I believe the problem is somehow related to humidity. I am in central Texas where winter usually means higher humidity, fog and rain. The last two days have been very wet and the time delay today was over 30 minutes. Three days ago the weather was sunny and dry and the time delay was the usual 1 second.

Here are the diagnosis checks I have performed so far.

1. Currently, the ECU does not throw a trouble code.
   
2. Eight months ago, the original main relay (RZ-0132) was replaced with a used (1995 RZ-0159) main relay to cure a hot start problem. (For $10.90 including shipping this was a far better solution than resoldering the old main relay). Currently, the solder joints of the main relay are perfect and the main relay tests good. The relays close audibly when power is applied and there is continuity across the proper terminals.
   
3. Just for grins, today while the long delays were still occuring, I removed the main relay, took the board out of its case, ran a blow dryer over the board at high heat, reassembled and reinstalled the main rely. None of this had any effect on the time delay.
   
4. Currently, the main relay wire harness tests good. The correct voltages read across the proper outlet holes and jumping the 5 and 7 outlet holes starts the fuel pump. This also means the fuel pump is good.
   
5. Currently, the MAP and TPS sensors receive the proper reference voltage, so the ECU is receiving power and communicating with sensors. Just for grins, I cleaned the plugs and contacts of the MAP and TPS sensors with electronics cleaning fluid.
   
6. Five months ago, a new battery was installed with new battery clamps. Currently the battery connections are clean and tight.
   
7. Currently, the grounding connection at the thermostat housing is clean and tight.
   
8. Three months ago, the ignition cylinder lock assembly and ignition switch were replaced because the original cylinder lock was worn and sometimes failed to turn without a lot of jiggling. Additionally, the wiring harnesses from the ignition cylinder lock assembly failed one of the continuity tests. Currently, the wiring harnesses from the ignition cylinder lock assembly test good and pass all continuity tests. (Jiggling or pushing in the key while turning does not work in case anyone is tempted to offer such a solution).
   
9. Since my Honda always starts on the first try after the fuel line is pressurized, I can not see any reason to diagnose the starter motor, distributer, ignition coil, ignition wires or anything else related to spark.

Now the big question: What else should I diagnose to track down this strange intermittent problem.

Update: It is now one day after writing the above, the weather is sunny with 32% humidity and my Honda is pressurizing the fuel line and starting normally.

Update (June 1, 2012): I still have this problem intermittently. I suspect the ECU has a glitch, but I don't want to replace the ECU on a hunch. My car always starts, I just have to wait awhile.