I apologize in advance for my lack of technical knowledge about my own car, but this problem is really driving me nuts, and I'm hoping someone here can help.

I have a 1994 Civic with just over 100,000 miles on it. Lately, it simply refuses to start on the occasional hot, humid day. The engine won't catch at all. If I wait an hour or two, it starts just fine, like nothing was ever wrong with it. Then it's good for a couple of weeks... until another random hot day screws it all up again.

I've taken it to my mechanic no less than four times, and at no point has he been able to even duplicate the problem, much less fix it. The car starts for him every time. It's maddening.

Does anybody have any suggestions as to the cause of this?

Thanks in advance,

Eric

 

Does it turn over and just not start, or not turn over at all??? If so I would bet it is the EFI Main relay, it's located under the dash on the drivers side. it's gray colored and has one or two screws that hold it in, it has a grey connector plugged into it. you should easily be able to get to it. if you need me to I will go out and take a picture of it...

My 1993 civic did that about a year ago. It's a $35 part from honda, you can only get it from the dealership, or at least that's the only place I could find it.

They are known for having bad solder joints on the circuit board in the relay, and on occasion on a hot day it will fail to engage, and your entire fuel injection system will not get power.

When this happened to mine, the engine would just turn over... initially a few times it would run for a second, then nothing... if I let it sit with the windows down, or doors open for a while so that the interior cooled down, usually took about half an hour, it would start fine....

 

That sounds mighty promising. Mostly it doesn't start at all, but on occasion it will *almost* catch but not quite. Like you, if I let the car cool down for a while, it starts fine.

If I really can trouble you for a photo of what we're talking about, I'd be quite thankful.

All the best,

Eric

 

Sure no problem... I know how irritating of a problem that was when it happened to me... That was the reason I joined HCF... and someone told me what to look for and all and it turned out to be exactly what the problem was...

Anyway, on mine it is a gray relay, on a metal bracket that is held inplace by one 10mm bolt. It is mounted against the drivers side kick panel, under the dash, Directly above the hood release, and directly beside the fise panel, as shown in the picture below... it will take some flexibility... but it's an easy plug and play... it may be helpful to take the old one lose, drive over to your honda dealer, pull it out and take it in to show them, so that they get the correct part.

you did mean that it just cranks but will not actually start right... and then after it cools it will start fine? because if it doesn't turn at all when you turn the key it could be something else... but if it is cranking and just not starting, then this is your most likely cause right here...

Thanks to my LG AX245 camera phone for being able to get in there to get this picture....

 

Ok, so i put the picture on my webshots account, but aparently the link is only temporary because now it's not showing up, so... try this one...http://img169.imageshack.us/my.php?i...7174500es0.jpg

 

You rock. I'll take all this to my Honda dealer. Thanks.

 

I have a 2000 Honda Civic SI and my car has the opposite problem. When it gets cold outside, it will start but won't stay started. I have to let it warm up for like 45 minutes before I can take off. I wonder if it is the EFI main relay also.. hmmm...

 

I'm not sure about the cold thing; I don't think it is the main relay though because a) usually happens when hot, and b) yours starts and then shuts off, with the main relay problem it will just crank and crank and crank some more, but wont start, because the fuel injectors have no power. Just a guess but maybe the Intake Air Temperature sensor is bad, or maybe the idle air control valve is sticking or clogged.

Sorry I said that mine would run intitally and then nothing, fpr some strange reason that happend only the first time I had the problem with the main relay, on subsequent problem days it never started until the interior of the car cooled off... You will notice when the main relay is working; that when you turn the key to run, but not all the way to start, after the fuel pump primes you will hear a click, if you do not hear that click the main relay is not working... that's how I determined for sure that it was the relay...

That's all I got on the cold start then die problem... maybe try posting a new thread with that heading... maybe someone else would have more thoughts on it...

 

Thanks a lot for this. It's been 2 summers since my Civic has been doing this and I even replaced the fuel pump thinking it was that. Now I finally got an answer. 'appreciate it.