This may apply to mid 80's - early 90's civics and accords as well. The pictures and instructions below are specific to 88-91 Preludes, but should other cars should be similar.
The Symptoms: Car will crank, and maybe run for a second, then dies quickly, and won't restart on a hot sunny day or after running the heater full blast for a while, and will start fine after cooling for a couple minutes.
The Cause: The solder points on the printed circuit board inside the main relay become cracked/loose over time and the heat causes them to expand just enough to break electrical contact.
(the main relay provides power to the fuel pump)
If you don't know how to solder or are unconfortable in repairing your own, you can probably take it an electronics store (not radio shack) and they can do it for you. Or just buy a whole new one.
What you'll need:
- Philips head screw driver
- small flat head screw driver
- 10mm socket
- rachet with 6" extension
- a soldering iron (I have a 30watt, but a 40w probably would've been better)
- some solder
- some time. If I had to do it again, I can get it out and back in, in about 30min. But you should probably give yourself about an hour to be safe.
Before starting, be sure you're ready to solder or have a replacement relay ready to go (your car won't run once you remove it).
Remove the coin tray covering the fuse panel.
Remove the 5 philips screws holding the plastic cover under the steering column. (1 in each corner, 1 where the coin tray was)
Unplug the 3 electrical connectors attached to the plastic cover, taking note where each one goes.
Using the 10mm socket and the rachet with extension, remove the 2 bolts holding the fuse panel up.
Work the panel out from under the dash. You'll have to disconnect some of the shorter wire connectors to get it all the way out.
Unplug the connector from the main relay. Use the small flat head screw driver to press on the tab that locks the main relay onto the fuse panel and slide the relay off.
Remove the plastic cover from the relay. You'll see the printed circiut board and all the solder points. Add a little solder to each making sure you melt the old solder.
Put everything back the way it came out and start it up!