1st post here. What do you guys make of this ?

I have a '93 Civic that won't start when it's humid. Even if it is just a really humid day, the car won't start. ( I'm in Austin, Texas BTW, so its not like Florida humid )

I have replaced the fuel pump and main relay with new OEM parts.

It was suggested to me that my ignition switch might have a short, but I didn't heed this advice since the car turns over fine, but just wasn't getting fuel.

Now I suspect it could indeed be the ignition switch.
Is there a way to test the ignition switch without pulling the steering wheel and airbag out ? ( It looks as if the steering column housing can't be removed without removing the steering wheel. )

Thanks

1993 Civic 1.5 L Auto with around 127,000 miles

 

I was in luck today since it is humid. This gave me a chance to test a few things. I jumped the main relay, and the fuel pump turns on fine and stays on.
The car has spark - but a very weak orange spark in all cylinders.

Now i have yet another question : If I jump the main relay, the fuel pump kicks on fine and i'm seeing that there is spark ( yes - weak, but enough to start )
So fuel + spark = fire right ? Why is the engine still not firing when i jump it ?

When I place the main relays back ( the new one as well as the original ) the fuel pump is silent.

 

When you turn the key on but don't start, the CEL should come on for 2 seconds, during that time the fuel pump runs. Then after 2 seconds, the CEL goes out and the pump stops. Another test of the ignition switch is to pull up the hand brake and watch the BRAKE light while trying to start. It should stay on all the time the key is at II(run) or III(start).

Orange sparks are not going to cut it. Take the distributor cap off and try to draw sparks from the coil output to a grounded test wire. You should have blue sparks that can jump more than 1/2 inch. If the sparks are weak there, replace the coil.

In dry weather, start engine and mist water on the spark plug wires while it idles. If that makes it stumble or die, replace wires. Also check the cap for cracks and susceptibility to dampness.

 

Thanks for the feedback. I'll try everything you suggested.

I know i'm repeating myself here but :

What has me puzzled is that if i jump the main relay, the fuel pump stays on - it just keeps going without shutting off .( which is possibly bad to do ? )

So fuel is getting to the engine right ?

I have the spark that is weak, but it seems like enough to at least make the car 'cough' and try and start, but nothing. I turn the key and crank the car with the main relay jumped and the fuel pump running, but the car just revs.

 

Well, the CEL comes on and the BRAKE light functions correctly, so I'm totally puzzled.
I guess the ignition is OK.
I also checked the fuses and they are OK.
The distributor has a new cap and rotor as well as plug wires. I didn't get around to testing at the cap itself today.
That's next.
( Im going to just install an entire new distributor, since I keep having weak spark.)
The spark is weak, but i'm sure it's enough to make the car fire when i jump the relay ....so i'm still puzzled.

It's so puzzling how that a car can be stopped dead in its tracks by a rain cloud overhead and not even a speck of rain anywhere in sight. Weird !

 

I'm going to replace the distributor this weekend. That might explain one of the reasons the car doesn't start, but it doesn't explain the fuel pump not coming on. The main relay is only a few months old too ( yes it is aftermarket, but i also have the original one too )

So I guess you guys are stumped on this one as much as me.
And this only happens when it is humid - even very slight humidity.
Weird !

 

Even a guess would be appreciated guys. I spoke with several good mechanics and they cant figure it out either.
Thanks.

 

I had a 1993 Honda Civic DX D15B7 1.5 Liter a year or so ago. If it only does it when it is hot or cold or raining, it is your fuel relay. These are easy to fix, just re-soldier 2 points and it will start every time.

Take your main relay from under your dash on the far driver side. Remove the circuit board from the plastic housing. Look for the 2 dry cracked solder points, and either re-solder the connections or put new solder over the top (the first method lasts longer). Put it back together and put it back under your dash and plug it in! problem gone!

Worked like a charm in my old 93 Civic D15B7.

Here is a link for more info:
Main Relay Fix, Troubleshooting (Honda, Acura) and how to solder

 

Thanks for the tip, but I'm positive that's not the problem. I did a thurough check of the main relay and its fine. I have talked to another mechanic and he days it might be that relay is not getting enough power to function.

Appreciate it though !

 

I tested every terminal combination as described in the Chilton guide and tested for continuity and they alk checked out fine and every combination produced a ' click ' as it was tested .