Hello, so Ive got a 91 civic DX that has been excellent to me except a small nagging problem that occurs randomly every few months. Ill be driving, and it will just quit. When I try to restart it, it takes anywhere from a few minutes to a few days to run again.

Here are the specs:

91' Civic DX
400,200km (I know)
new spark plugs
new pcv valve
new oil filter/new oil
new fuel filter
new air filter

The car has been running great, Ive owned it for a year now (ive put about 25000km on it), but this problem has been occurring since I bought it.

Heres my best description of what happens; you'll be driving at any speed in any gear, and it just completely dies. Everything electrical in the car remains on, but the engine light comes on and it just wont start. It will be still driving at some speed, and I'll even try dumping the clutch and "push starting" it while it still has speed, and it still wont fire. Its almost as though its not getting enough fuel, and I cant figure out why. I have noticed though, that it has only ever done it in humid conditions. It will start and run fine in minus 40C (with no block heater , but seems to give me problems in humid weather. This leads me to believe that its something to do with water or vapor getting into some electrical component or computer somewhere. Ive also heard that its a common problem that humidity can get into the silver bonding compound that bonds the ECU to the board. (?) This could all also be luck of the draw and have nothing to do with humidity altogether.

These are the diagnoses that I have ruled out:

-Fuel pump - you can hear it come on when you turn the key to ignition
-Spark plugs - just replaced them this fall, they should be good
-fuel filter - just replaced
-battery/ignition - just tested battery, 14.4, working good.

My best guess is that its is the ECU, what I was wondering is if anyone had any decent advise on this before I pay to have it checked out.? I realize that there are other topics pertaining to this problem, but they were not exactly specific enough for me. Any help at all would be greatly appreciated, I love this little car and want to keep it and fix it up eventually.
Thanks

 

When it won't start, pull up the brake handle and make sure the BRAKE light on the dash stays on while trying to start. If not, the ignition switch is likely the problem. If it does, do a spark test. Also check that the CEL cycles on and off like it should when you turn the key on and don't crank. Turn the key on and don't crank and check the LED for any codes. All this testing has to be done only while it won't start.

It could also be simply the spark wires or cap shorting out when damp. That is easy to test, idle the engine and mist water on them.

Bottom line is don't replace ECU until everything else has been ruled out. It is almost never the problem.

 

hey! thanks a tonne for your reply, it has helped narrow it down even more. now that I think about it, there has NEVER been any brake light that comes on when I pull the E brake! im thinking this is the problem. Last night I pulled the entire distributor out and did some spark tests, cleaned out the distributor/rotors and contact points. I also checked the entire thing for cracked wires or damage. It seems to be working well, all the brass contact points are good. My next tests today are going to be on the coil. I suppose if the problem is with the switch, the coil and dist. wont be getting any power. Thanks again for the timely response, I really appreciate it. Ill post how it goes today, wish me luck.