I posted this problem a while back but it has gotten worse (or atleast different). I'll recap but you'll have to read the whole post to get all the info. It's a 92 Civic EX

First time I had a problem was after a two hour road trip. Pulled into a store for 5 minutes and tried to restart but it would crank and not start. Waited a few minutes and it started right up. Classic main relay but it began to have other symptoms so I put the main relay in the back of my mind.

Then whenever it was up on jacks or parked on a large incline it would do the same thing even after being taken off of the jacks. This would happen whether it was warm or the car was cold.

As the summer got hotter, the main relay symptoms started coming back where the car would always start first thing when it was cold but if it was warm or had been sitting in the sun all day it wouldn't start for a few minutes. It just cranks.

Took the main relay out and saw one possible cold solder joint and several with very little solder at all. I reloldered all of the posts. I solder for a living and have been to several soldering courses in the air force so there is no chance that I made bad solders. As a matter of fact all of my solders are textbook.

Now the problem happens whether it is hot or cold and seems to be even more when it is cold. The CEL will sometimes come on for 2 seconds and go out when the key is turned to on and it will start right away. Other times it will come on for 2 seconds and not start. There are times when the light will come on and stay on and and not start and still other times when the light won't come on at all but will still start.

The latest thing it has been doing the past two trips is a slight "diesel" when it is shut off.

It has a new fuel filter that I replaced as soon as I got the car maybe 3-4 mos. I can't really hear the fuel pump all of the time but could that be because it's already primed?

Another bit of info which may or may not be related is that one day I had to accelerate kind of hard on the on ramp and the CEL came on. Got home and turned car off and back on and CEL was gone. Stuck the paper clip in the diagnostic port and the CEL flashed 1-1 at normal brightness and normal speed immediately followed by 1-1 really dim and really fast. So it was like 1.....1..(1.1.....1......1..1.1...). It repeated this infinitely.

Are the actual switches inside the relay sticky maybe or bad (weak) fuel pump? If the switches are sticky inside the relay would an electro safe spray solvent free them up?

Thanks in advance.

 

Sounds like codes 1 (O2 sensor) and 20 (ELD), which are unlikely to cause the starting problem.

When the engine won't start, listen for whether the fuel pump primes for a few seconds when the key is turned to ON and also check for spark at the plugs.

If you don't hear the fuel pump, then it may be intermittently faulty given that you resoldered the main relay. To verify, test whether the fuel pump fails to prime despite getting battery voltage when the key is turned to ON.

 

If you resoldered the relay properly then it would not be the relay as there is no indication that the relay will fail due to mechanical malfunction, only solder breakdown.

 

Yes, but any relay can become contaminated or sticky over time though this one is not in a location that would be prone to pick up contaminates.

Just now it wouldn't start again. CEL comes on and stays on (this time). Can't hear the pump prime. Took relay out and tapped it on steering wheel a couple of times. Car starts right up. Still couldn't hear the pump prime but that could have been because I had no one to turn the key for me and by the time I got back there it was done. I should have closed the door because the chime was ringing in my ears.(No dieseling after 30 minute trip this time)

Not sure if it was the taking relay out and reinserting, tapping it, or if it was the fact that it had been 4-5 minutes and was going to start anyway. Car had been sitting for 4 hours in the middle of the night so it was nice and cool.

I do need to check for spark. Being that the car will usually start in a few minutes, any troubleshooting has to be done quickly.

 

If it turns out that tapping on the relay can consistently make it start, you need a new relay.

Check the ground wires on the engine thermostat housing. The CEL should be on or off, never dim. That suggests inadequate power or ground to the ECU.

Also you could take your ECU apart to inspect and resolder any questionable connections. These have a double layer plated-thru board so solder failure is much rarer, but can still happen. Always disconnect the battery before unplugging or replugging the ECU.

 

Today, tapping the relay fixed it twice and failed to fix it once. For $44 at oreilley's I may as well get a new one and be done with it.

A funny thing I noticed today also was that when the key is turned to on the CEL does not come on at all and the car starts. If the CEL does come on, it's a 50/50 shot at starting even when it goes out after 2 seconds.

 

Prior to purchasing a main relay, inspect the main relay connector for damage to be sure it is not the source of the problem.

 

well, it started everytime today but the CEL would never come on at all like it is supposed to. Weird.

I'll wait to check the connector until it won't start again. I'm afraid to touch anything now that it's starting. I did give it a quick look when i first removed the relay but i'll give it a better look next time.