I have a 1990 Civic EX with a 5-speed manual and a 1.6L engine. On hot days, there's no spark. I've changed the plugs, wires, cap, rotor, ignition coil and ignition ignitor. When it does run, it runs a lot better now with all the new ignition stuff, but if I let it sit in the summer sun, then try to start it, there's no spark.

If the car is already running, it doesn't quit. It doesn't seem to have anything to do with the engine being hot, since I can drive it all morning on a cool day, and it will start right-away.

Any ideas?

Thank you

 

When it doesn't start do you have 12v to the yellow+black wire going to the distributor?

 

Won't start on hot days always think main relay first. Then consider other stuff. When it won't start, turn the key on don't crank-- does the CEL come on then go out after 2 seconds like it should?

 

Thanks for helping me with this.

To measure it, I pulled the plug, just above the distributor. The Yellow+Black wire gets 12v with the ignition on, and drops to 10-11v when cranking. To measure it without unplugging it, I'd have to tap the wire. Do I need to do that?

 

The CEL stays on when the key is in the #2 position.

I'll need to wait until morning when the car is cool before I can check that it turns off after a few seconds.

 

Okay, so based on all this, I pulled the main relay this afternoon and re-soldered all the solder joints on the PCB. I didn't see any obvious broken ones, so I'm crossing my fingers that this is the problem. By the time I put it all back together, the temp dropped to the high 70's from the low 100's. The big test is tomorrow afternoon, when it gets hot again.

I'll report back.

Thank you.