# Main Relay or Vapor Lock?

**URL:** <https://community.cartalk.com/t/main-relay-or-vapor-lock/62894>\
**Category:** Maintenance/Repairs\
**Tags:** civic, honda\
**Created:** [March 22, 2011, 9:24pm UTC](https://community.cartalk.com/t/main-relay-or-vapor-lock/62894 "2011-03-22T21:24:45Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![azamora](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@azamora](https://community.cartalk.com/u/azamora)\
**Post date:** [March 22, 2011, 9:24pm UTC](https://community.cartalk.com/t/main-relay-or-vapor-lock/62894/1 "2011-03-22T21:24:45Z")

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1990 honda civic lx  
  
 Won’t start after being in heat/hot sun. Starts after 5 min or when it cools down.

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**Author:** ![shadowfax](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/shadowfax/32/13026_2.png) [@shadowfax](https://community.cartalk.com/u/shadowfax)\
**Post date:** [March 22, 2011, 9:26pm UTC](https://community.cartalk.com/t/main-relay-or-vapor-lock/62894/2 "2011-03-22T21:26:40Z")

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Main relay. Easy to swap. Very common on that era Civic.

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**Author:** ![Goldwing](https://avatars.discourse-cdn.com/v4/letter/g/e68b1a/32.png) [@Goldwing](https://community.cartalk.com/u/Goldwing)\
**Post date:** [March 22, 2011, 9:27pm UTC](https://community.cartalk.com/t/main-relay-or-vapor-lock/62894/3 "2011-03-22T21:27:57Z")

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Buy a main relay and replace it. $30 - $40. You can replace it yourself.

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**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\
**Post date:** [March 22, 2011, 10:20pm UTC](https://community.cartalk.com/t/main-relay-or-vapor-lock/62894/4 "2011-03-22T22:20:49Z")

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If the main relay is not the problem then it could be a faulty ignition switch. Some Hondas are under a Recall for switch problems (yours is not) but by the same token, many non-recalled vehicles of the same make also suffer the same problems.

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**Author:** ![mcparadise](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mcparadise/32/32_2.png) [@mcparadise](https://community.cartalk.com/u/mcparadise)\
**Post date:** [March 23, 2011, 12:13am UTC](https://community.cartalk.com/t/main-relay-or-vapor-lock/62894/5 "2011-03-23T00:13:57Z")

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I’m betting on the main fuel injection relay. Under the dashboard. Common problem with older Hondas.