Honda won't start when hot

I maintain my mother-in-law’s 1990 Honda Civic. It is in very good condition and has only 54,000 miles. This summer is has it has begun showing a problem starting. It starts great and runs great when it is cool (mornings and evenings) but will not start in the hottest part of the day. It stays outside so there is no avoiding the heat. It does not have any problems starting or running when the car warms up from operation, only when it has been sitting in the hot sun. I have heard that this model Honda has a problem with the main relay that can cause this problem as it ages. Can anyone verify this for me? If so I will try this fix first. I will be glad to hear any ideas from any one interested.

You sure describe the common problem with the main fuel pump relay on Honda’s. And because of this, that’s the first suspect.


As usual, Tester is correct. What has been described is the classic symptom of main relay problems with Hondas of that era.

Yep. Also, known as the PGM-FI relay. Just google.

Thanks to all who answered my question and I also searched past postings on this subject and found a wealth of information. Thanks to Click and Clack for making this resource available.

Great Show,
AJ called in on 7/4/09 about his 1992 Honda accord not starting when it was “hot” outside.
Been there done that with the same model and year car.
I feel for him going to all the mechanics that could not fix it. I surfed the net and found out what was wrong.
“IT IS THE MAIN RELAY”. I bought a new one for $35.00 and replaced it myself. Never had the problem again. It seems as thou when it is “HOT” outside, the factory Main Relay solder breaks down? and will not work until
it cool down inside the car. I hope you can contact him with this simple fix.

Actually, it’s Thanks to the responders who make “this resource” possible. Think of it as symbiotic relationship.
You are Welcome.
Hellokit, a responder.