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1990 Civic DX Won't Start When Hot

Old 07-18-2011, 03:09 AM
jpj is offline
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Correct. To be clear, the first click happens when the key is turn to "run". Then one of two things will happen:

* The pump will not run and the 2nd click will not happen and the CEL will switch off.
* The pump will run and switch off with the 2nd click and the CEL will switch off.

It used to seem that there was a pattern but I've noticed that either of those two things can happen and the car may not start. The first point, however, guarantees that it will not start.
Old 06-02-2015, 01:35 PM
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Question 1989 Honda Civic won't start

I'm wondering if you ever found out what was wrong. I am having basically the same problem with my 89 Civic:

1. It starts fine in the morning or when cool;
2. When hot, it will start if I turn off the engine, and restart immediately, but won't restart if I leave it for a couple minutes.
3. It gets spark;
4. When it won't start, the CEL goes on and throws a code 16;
5. The car runs fine once it starts.
6. My mechanic has replaced the starter motor, spark plugs and cables, and distributor, and rotor cap (to the tune of hundreds of dollars);
7. I replaced the main relay. It's not the main relay.

I'm disinclined to take it back in to my mechanic without getting a better sense of what's going on. Any help would be appreciated.

Old 06-03-2015, 12:51 PM
jpj is offline
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Well, it's been so long that I no longer have that Honda. Sad, really. I miss it.

Your symptoms sound a little different than mine. My car just would not start on a hot day. Maybe one time out of a hundred it would start and, once started, it would run indefinitely. The problem was definitely the infamous Main Relay. The problem I ran into was that a couple of the parts stores I would go to had the incorrect relay listed as the main relay. To make matters worse, this other relay was located near the Main Relay in a more accessible place so I never thought twice about it. This caused me to write off the Main Relay as not being the problem early on. I ended up replacing many other parts with no effect. I don't recall how I figured it out, but once I found I had been replacing the wrong relay, I ordered a Main Relay online, replaced it (which was a bear; it was way up under the dash near the steering column), and it ran fine.

I had a lot of ignition related problems with that car over the years and I got to know it pretty well. For example, if it ran rough and stalled while driving, especially if it was raining, it was the igniter. If you've had the entire distributor replaced (which would cover the coil and igniter), I would revisit the Main Relay. Find some pictures online and verify. More than one parts distributor had the incorrect part on file for a "Main Relay". Even on some online shops had it incorrectly listed. If you're definitely getting spark, are you getting fuel (remove a plug and turn the engine over a few times. Does it smell like gas?)? The tell-tale sign for the Main Relay is that you won't hear the fuel pump "click" on when you turn the key into the "on" position (just before "start").

Best of luck!
Old 06-03-2015, 02:40 PM
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If the car starts fine but won't restart a few minutes after shut down on a hot engine like you stated, my guess would be that you have a leaky fuel injector. It won't start due to it flooding the engine.
Old 06-04-2015, 11:17 AM
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Actually I think my symptoms are the same. I live in Seattle and up until recently the weather has been relatively cool. My guess is that if the cabin temperature is above about 80 degrees it won't start. I've been paying attention to the clicking on the main relay and based on my sample so far, every time it won't start the main relay doesn't click (even once) and therefore the fuel pump doesn't turn on. I found a discussion online which provided an electrical diagram of the main relay. If it won't click even once it means either:

1. The main relay is bad;
2. The cable from the battery is faulty;
3. There's no current from the ignition.

If there's no current from ignition, then that's a separate diagnostic. It was interesting to hear that you didn't get the right part when you replaced the main relay. I'm wondering if that's the case for me. I think what needs to be done now is to check the various electrical paths to the main relay for continuity. I'm not sure if I'm up for that. Sigh. Thanks for your input.
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