I have a 1999 Honda Accord with @ 135xxx miles on it. The only problem, it won’t start when it’s hot! When it starts to cool down in the evening and in the spring, summer, and winter it starts without hesitation and runs with no problems. Does anyone know what could be causing this?
Excuse me, I meant spring, fall, and winter.
Well, clearly the Accord is a Canadian car… 
Seriously, though, I don’t know. Vapour lock somewhere maybe?
Does the engine even turn over? if not possible defective starter.
This is the classic electrical relay problem that Hondas and Acuras of that era are subject to. Since the relay is in the car’s interior (under the dashboard, near the steering column if I recall correctly) the super-heating of the car’s interior on a hot day will cause it to fail temporarily. Since this relay is connected to the circuit for the electric fuel pump, you are not going anywhere in 90s vintage Honda on a hot day!
Any good parts store should be familiar with this problem relay, and should be able to sell you the right one without any problem. Once you have the replacement in hand, it should be pretty easy to spot the old one under the dashboard and swap it with the new relay.
VDCdriver–as usual, logged out again by this problem-ridden new site!
I concur with VDC. This problem has been posted here many times, and there have been techs highly experienced with Hondas that have all immediately pointed to that relay for those symptoms.
Oh, yeah, I’m mountainbike. I’ve given up the struggle to stay registered.
I agree that the problem is the main relay and also that this site needs some work.
Currently logged in, but that’s subject to change in a heartbeat.
The main relay problem was beyond common in older 89-91 Civic/Accords. However it could be one of many possibilities. I am not convinced.
I thought by '99 they fixed that problem. I guess we need more info on what the car does when it won’t start.
It will turn over, kinda sounds like it’s flooded just won’t start.
I agree with the main fuel pump relay theory. This is a classic case. Replace the fuel pump relay, also known and the PGM-FI main relay, under the dashboard.
I agree that the problem is the main relay and also that this site needs some work.
Perhaps the site needs a main relay? 
For anyone who has a start problem on a Honda (or any car), you can go to www.tegger.com/hondafaq/startproblems.html. This site has some good info if you care to click and read.
Sadly the problem persists past '99. My '00 Acura had the same problem, the relay was replaced twice over the last year. I’ve found it advisable to park in the shade with the car level or facing down an incline. Doing that, the problem hasn’t reappeared.