2000 Honda Odyssey, 130k miles.
Started off as intermittent no-start. About once every 10 starts it would crank but not start. Usually within a couple hours after a no start it would start up normally again.
When the car does turn on it runs beautifully.
I've noticed that the battery (new 6 months ago) seems to die very quickly. It's good normally, but if my 2 year old plays in the van with the dome light on for 20 minutes the battery may need a jump.
A few months ago the trunk open light came on while driving and has never gone off. Replaced the latch twice and that didn't fix it (may be a completely separate issue, but just trying to give all the details).
Check engine light came on (P0172) showing the engine was running rich. No effect on how it drove. Traveling mechanic said it was "wet spark plugs". He removed the fuel pump fuse, turned the key for a few seconds, and put the fuse back. The check engine was off and the car happened to start so he thought he solved the problem. Pretty soon the light was back and the intermittent no-start continued.

Left the van at a shop for a week and of course it started up just fine every time they tried so I took it back.

Some of the lights on the dash have never worked since we got it 5 months ago (the clock backlight (if there is one) and the backlight for the gauges). Additionally, some of the little lights behind the buttons (AC, window defrost, etc.) sometimes work and sometimes don't. Unclear as to if the buttons are functional when the lights don't work. Recently it appears that the climate control temperature dial completely stopped working. I can control how much air blows, but the air is always blazing hot. This was not a gradual thing, just all of a sudden one day it only blew hot air. The dash lights were not working at the time. The rear control AC did work, just not the front AC.

I haven't been able to start the car at all today. If I hold the key forward for a while it'll grind a bit while trying to start.

Fuel pump was replaced 7 months ago and I hear it turn on when I turn the key. Green key light on the dash turns off after a few seconds (as I believe it is supposed to).

A couple of things I've read that I'm considering- main relay and ignition switch. I've got both these parts on order in case they solve the problem.

Any help is appreciated!

 

The cranks but no start,,,,,is that after a hot soak (cars all warmed up and you stop to get gas or something and then it doesn't want to start)? Cold start in morning?

That trunk light will cause the BCM to not be able to sleep which will drain the battery much faster than normal.

This garage doesn't have a scan tool? They are idiots whoever they are to not at least look at a couple quick things to get direction on how to troubleshoot it. A scan tool will show the freeze frame which will have the data of the system when the code set. It will also show current information like the ECT and such. This is critical to fuel delivery which is your problem. For some reason the system is adding to much fuel. The ECT is critical as if it reads 10 degrees low it will set rich codes.

As for the lights you'll need to go after them. The head unit of the AC unit may need replacing but first try a reset of the system.
AC reset
Turn the system on full cold Max AC.
Radio OFF.
Turn ignition OFF.
Pull the HVAC (AC) fuse from interior fuse box. Leave out for 1 minute and replace.
Turn key to run/on position....NOT start.
Do not touch any controls. You'll hear the doors (actuators) being opened and closed. The HVAC module is learning the full open and full close positions. Wait until the system is completely done with the learning process. Less than a minute.
Start and test the system.

As for your current no start. You say if you hold the key to the start position you can hear the starter grinding. Is that correct?
If so then all the wiring from the ignition switch to the starter are working or the starter would not be doing ANYTHING. If the starter is not working the relay and ignition switch may well cure that problem. I would say it's the ignition switch.

 

Crank but no start was originally in the morning and only after a few days of not driving. Now it hasn't started for 2 days, but originally it was definitely just early in the morning.

Thanks for the AC reset instructions.

When I hold the key to the start position it cranks normally for 3-4 seconds then it tries to start and that's when I hear a grind.

 

Do you have a dvom?

 

Yup I do, what do you recommend?

 

Do you have diagrams? I have them for the 99 but not your 2000. How about a scan tool or fuel pressure gauge?