GlennH

First of all I checked all the old posts regarding no start problem.

Car has 40k original miles and ran great. Excellent car. Yesterday morning, went out to start it. Able to crank the engine but it doesn't start.

Battery is fine.
Checked for spark and there is spark.
Cleaned and tightened the ground on the thermostat housing.
I checked all the fuses, both under the hood and under the dash. All were fine.
Checked the main relay and all soldering points look excellent. No cracks detected. The car was in a mild California climate until 2014 when it came to Arizona

When put key on the ONII position (but without trying to start the car), I couldn't hear the fuel pump prime.

Based on this helpful post http://www.clubcivic.com/forum/threa...l-pump.210565/
I did the following.

Removed the main relay under the dash and connected Terminal A1 to Terminal A7, using a wire. I could hear the fuel pump run, even without having the key in the ignition
Then I connected Terminal A5 to Terminal A7. I could NOT hear the fuel pump run.

Next, with the main relay in place:
1.Turned key to ON(II).
2.Grounded the A7 and then A8 terminal (Grn/Yel wire) individually to the metal frame under the dash.

When I grounded A7 nothing happened.
When I grounded A8, I could hear the fuel pump.

Since the fuel pump is running, I'm guessing the fuel pump is not the issue.

How can I determine whether the issue is the main relay under the dash or the ECU unit? or maybe there is some other issue?

Also, in the link to the helpful post that I noted above, it indicates that fuse 24 and fuse 31 should be checked.

Does anyone know what these fuses are and where they are located? The fuses under the dash only go up to fuse 27, and fuse 24 is for the electric window. Also, I don't find a fuse 24 or 31 under the hood.

Thanks for your help

ChrisS

Based on your information, I think it's the main relay. (Jumpering terminals = working fuel pump)
How did you inspect the main relay's solder connections? (Pull the plastic cover off and look at the connections using a loupe; any discoloration in the solder could be cracking)
I'm pretty sure the main relay also supplies power to the ignition circuit.

Simple ECU test: turn ignition switch to ON, check engine light should light up, wait 5 or 6 seconds, check engine light should turn off.

picture of main relay solder connections with cover removed:
-circled in red = cracked solder
-circled in yellow = suspected cracked/heat stressed solder
(from my 1991 CRX Si with maybe 200k)
[ATTACH=CONFIG]84953[/ATTACH]
detail:
[ATTACH=CONFIG]84954[/ATTACH]

GlennH

Thanks Chris appreciate it. I took out the relay again and double checked the solder joints with a magnifying glass, based on your photos. The solder joints still look like new on the relay. Maybe because it has low miles and was kept in a mild climate.

I guess it could be the relay. Maybe the cracks in the solder are not obvious or noticeable.

GlennH

I also posted my problem at clubcivic.com. In case anyone is following this thread and also to possibly help someone who has a similar problem in the future please check clubcivic.com for status of the problem. 29 posts so far.

http://www.clubcivic.com/forum/threa....232885/page-1

If anyone has additional input, but doesn't want to sign up at Club Civic, please post your advice here. I'll be checking back.

Thanks again for any help.

GlennH

I replaced the C14 Capacitor on the ECU (desoldered the old one and soldered in the new) and haven't had a no start issue during the last two days. Recommend, for anyone who hasn't done so, replacing the C14 capacitor, as this one is known to fail in older ECUs, and failure could lead to a damaged circuit board. In my case the capacitor looked fine on the outside and circuit board was undamaged. If anyone needs a C14 capacitor, PM me and I'll mail one for three bucks, including postage.

GlennH

Update

Car is running great. The capacitor was definitely the problem

"What are ECU capacitors & why it is important to replace them":

http://www.phearable.net/blog/ecu-capacitors.html