PURPOSE: To fix the faulty main fuel relay (MFR) by means of resoldering several connections, which can be done with a 99cent soldering gun and save $40-50 from buying a new replacement relay.
BACKGROUND: The ever popular gripe with hondas and one of the top reasons why our cars won’t start, a faulty main fuel relay. The problem usually comes to surface during a sudden heat increase in weather, causing several of the soldered connections to crack within the relay. When you turn the key to the ON position, you should momentarily hear a click from the relay when the check engine light turns off.
here the relay is #18, which is located right beneath and to the left of the steering column.
TOOLS:
-phillips screwdriver
-flathead screwdriver
-10mm socket and extension
-soldering gun of your choice (99cent one will do fine)
PROCEDURE:
disconnect the negative terminal from the battery (why of course, we always do this, don’t we?).
remove the lower panel under the steering wheel. its just a few screws but you can refer to your manual (why we all have downloaded the helm’s and/or purchased a haynes manual didnt we?).
locate the relay and remove the 10mm bolt holding the relay bracket in place. the relay is in direct view, about six inches in and a few inches to the left of the steering column. you cant miss it. its actually mounted backwards with the bracket facing you and the label facing the front of the car.
reach under and unplug the connector on the bottom of the relay. you may need to contort yourself upside down there to get enough leverage.
now that you have the relay and mentioned what an interesting device it is, remove the entire cap by prying out the bottom with your flathead screwdriver.
here is what it should look like
notice the two larger soldered connections at the top middle and the one at the bottom middle. all three of mine had visible cracks.
now the fun part. take your soldering gun and tin it by letting a little bit of fresh solder melt on the tip. place it in the middle of the joint and wait for it to begin to melt. once it melts, swish it around a little so you get an even puddle. repeat on the other cracked connections.*
*note: ok now that you noticed i have unparalleled soldering skills, here is where your procedures may differ. since i am lazy and commonly known to have insane tendencies, i actually used a 150w/230w craftsman soldering gun to melt the crap out of it (cuz it was there).
the rest of you may opt to do it with a little more skill (is that even possible?), with the proper soldering gun and using a wick or vacuuming out the old solder to melt in fresh solder. it may take a tad bit longer, or you can do it my way in about 12 milliseconds.
clean the contacts. say, “damn that was easy” and reinstall the relay. reconnect your battery and notice how easily your car starts now. if not, you probably burnt something and this is where i take no responsibility for you listening to such a ghetto rigger like myself
When you turn the key to the ON position, you should momentarily hear a click from the relay when the check engine light turns off.
CONCLUSION: well its easy and it works. my car wouldnt start the other day and i noticed it was quite hotter that afternoon. proceeded to do the above and it started without a hitch. usually i have to wait like 15-20 minutes before it starts again.
you know i still get the delayed start. its only happened like twice since i soldered the relay though. click… click… no click… click… start. maybe i overheated it once or twice with a little too much power and really cooked it inside, or its just plain old. didnt look too easy to take apart without breaking something either.
a shot in the park here, i read over on h-t that its not rare for fuel injected vehicles to sometimes exhibit this behavior, exclusive of the main relay. the topic of discussion was the hard to start behavior of dsm 450cc’s. i just installed mine and for the first 10cranks/15minutes i got nothing but clicks, then it just magically started, just like the stock ones. its been two days and its been starting perfectly…
I believe vapor lock can cause this. On warmer days the gas in the fuel line inside the engine compartment may vaporize to some degree. So you have to keep cranking until enough fuel is delivered. Sometimes I even get on the gas pedal a few times. I’m not sure if that does anything though.
I did this on my car the other day and it has been working perfectly since, and I live in Az so it’s nice and hot here. One extra thing i did to it was instead of just swirling the Iron in the solder, I actually dabbed on a little more solder onto each connection.
you know i think i cooked mine too much. ive been getting it once in a while again, with no consistent weather conditions. whats funny is that once i start jiggling it (i didnt attach it back to the post), it starts immediately. i.e. i turn the key and nothing, leave it in the start position while jiggling at the same time and itll start. i guess the 220w was a tad too much for the internals. either that or the wires a little loose from all that fiddling. its ok i have a spare that i lightly resoldered lying around.
When I looked at mine I couldn’t see any cracks like you said you did on yours. That’s why when I did mine I added a little solder to each connection. As I touched the soldering iron to a couple of the points the amount of solder was so little that it all just stuck to the iron and there was none connecting the pin to the board, so I added more until it didn’t all stick to the soldering iron and there was a nice puddle connecting the pin to the circuit board.
basically i think the problem on mine was the lack of solder in these 2 particular spots or maybe just a cold solder joint somewhere.
I hope this works for me. But my situation is different. I didn’t have trouble starting. In fact it rarely had trouble starting. My motor just decided to shut off in the middle of the highway doing 60 mph. And after that the car won’t start. I hope the problem is as simple as resoldering the relay.
Originally posted by grillorugh I hope this works for me. But my situation is different. I didn’t have trouble starting. In fact it rarely had trouble starting. My motor just decided to shut off in the middle of the highway doing 60 mph. And after that the car won’t start. I hope the problem is as simple as resoldering the relay.
after that the next two most common problems would be the ignition coil and igniter. you can diagnose these with a voltmeter (5-10$ at radioshack or pepboys), with the instructions in the manual. only use genuine honda replacements.
I found out why my car died. I removed the distributor cap to test the coil and what did I see??? The rotor was completely loose! Apparently the rotor screw fell out and the rotor just spun off the spindle. I hope that’s why the motor shut off on the highway yesterday.
