I ACCIDENTALLY DELETED MY ENTIRE POST

1990 Civic DX
B20Z swap
OBD1 conversion
wire tuck

I did everything myself


ENGINE BAY


HARNESS(i am not trying to take this apart)


THINGS CHECKED, TESTED, & PROVEN GOOD:
main relay(had two. reflowed solder joints on one)
fuses
grounds
switched out multiple ecus
fuel pump
ignition switch
swapped the engine bay fuse box bc mine was cracked

So, let me tell you what's going on... I'm not getting power to the fuel pump but it's working bc i jumped the power wire directly to send fuel to the engine. but it would only turn the engine over and i tested for spark and got nothing

I did the main relay test, everything went smooth... and the harness test and ended toward the end of the test where i highlighted and did voltage readings



im starting to run out of ideas


now it turns a little bit and then stops and starts clicking repeatedly. no engine lights. the engine light wont cut off obviously without the proper electricity flowing through the appropriate wires

 

I had a 90 hatch that had power to the clip/plug under the rear seat but not out the other side i just spliced it n it was good to go. Easy check. Good luck.

 

Just because the main relay clicks, doesn't mean it is 100% working. There are actually 2 relays in the main relay so 1 might be clicking and not the other.

There is a yellow/black on the main relay that sends power to the fuel pump.
i'm not sure if that is the same wire you are finding 'dead' under your seat, but it sounds like it.

There is also another wire on the main relay that is black/yellow. If you don't have power on that wire, then the yellow/black to the fuel pump won't get power when the relay shuts.
The black/yellow gets power from a fuse fed by the ignition switch.


The valve cover ground doesn't ground anything electrical. the valve cover is insulated with rubber gaskets everywhere it contacts the cylinder head. The purpose is to prevent galvanic corrosion.

 

I have the same problem with my F20B swapped 88 hatch. For now, I've just jumped two wires on the main relay plug to keep the fuel pump always on while the ignition is on. It's a lame/temporary fix, but it works. Still troubleshooting.


I've replaced my main relay twice (one new relay, one junkyard relay) to no avail.



If you want confirmation that the fuel pump works, your engine starts, and there are no fuel leaks, put a wire between the black/yellow and yellow/black wires on the main relay plug.


Edit: 4drEF ninja'd me lol

 

When you put two dissimilar metals (like aluminum and steel) in electrical contact, one of the metals will corrode over time. Even though the valve cover is insulated from the head and the rest of the block by gaskets, the oil joins them together for an electrical connection. It's not a great connection, but it is enough to cause corrosion over time. Water has this effect also so many people add a ground strap from chassis to the radiator when they use an aluminum radiator. You can even buy sacrificial anodes for radiators so the anode becomes the weak link and corrodes. These anodes are found on most home water heater tanks as well.

 

so you def suggest me to get a ground from the vc? :/ :C

EDIT: also, do relays just die from a car sitting over a few years? the fuel pump ran just fine before i pulled the engine out a few years ago

 

Yes, heat humidity from a closed car warming and cooling.

 

okay, so... i bypassed the fuel relay by sending the power straight to the battery bc i changed it out and it did nothing. the fuel pump IS NOT bad.

idk where the issue with the fuel pump is at with not getting power. i cant have constant power to it, right? or am i wrong? my check engine light stays on so im going to try a different ecu and then look to see if i have spark.

the engine is turning.... got the fuel to the engine.... still no start

 

I would trouble shoot the POWER INPUT to the main relay and if it's good then the POWER OUTPUT to the fuel pump.


If it is cranking, you can check if it's a fuel issue easily by shooting starting fluid into the intake. If it stats up on starter fluid then you have a fuel problem.

 

it's more than likely an electrical issue somewhere. im not getting power to the relay or from the relay except in the other wire than the one that i need to power the fuel pump.

tried a different ecu

checked for spark... got nothing

4drEF i already put fuel in the motor. bypassing the power straight to the pump showed me that the pump still works. just didnt want to spark. where do i find the power source input that leads to the relay

 

Right here
https://honda-tech.com/forums/showpo...67&postcount=6

 

Why waste time testing the relay, just pull it out; re-solder the joints and if it works great if not get a new one. Takes like 15 minutes.

 

So you are suggesting to remove the relay, open it up, reflow the solder, close it up, and try it?

Why waste time throwing parts at it?
If he just verifies INPUT power on the black/yellow wire then he might find that the ignition switch is bad. How does reflowing solder help that?

 

Doesn't have to throw parts at it, just some solder; I already had a soldering gun and solder, and 20 minutes to do it; you'd think he would spend more time fiddling with a voltmeter; overkill but most of these relays go bad anyway, not a bad idea. I personally don't like sticking my head under the dash for too long but it's up to him whether or not e wants to test the wires.

 

Do the main relay fix the trouble ?

If not, i would test the main relay harness just like in this thread :

https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/checking-main-relay-pics-2535047/

 

well, i thought i cornered the problem with the ignition switch. that is a NO GO. still struggling to get this thing started

now it just turns a couple times and clicks like crazy. fuel pump STILL not priming on its own. and im not getting spark when i bypass the power straight to the pump

and obviously the engine light is not cutting off

 

make sure you got all your grounds tight, mainly the one on your t stat housing.

 

grounds are all tight, tested and grounding out a perfect voltage directly from 12v

(changed the OP to get everything all together to make reading/HELPING easier

 

is there anyone out there?

 

Do you get any work done with the main relay yet?

Looking at the voltage tests you put up from testing the main relay harness, it really does look like a bad main relay.
You can give a go at reflowing, but no guarantees there. Since you are reading 0.75 on the output it seems that the relay is working, just not well at all.

If you don't have a main relay handy, you could jump the black/yellow to yellow/black just to test it out.
This should get the 12V to the pump just like the main relay is supposed to do.

 

ive tested both main relays ive got and ive reflowed one of them and both successfully pass continuity. like i said, they are BOTH good. isnt the yellow/black wire already supposed to have its own voltage??? not transferred from the relay

ive also jumped the power to the harness. something is messed up in the main harness or the jumper harness. its gotta be.


also, whats the .75v got to do with the relay? its tested directly off the harness, not with the harness AND relay together

EDIT: also, the number 8 wire thats yellow/black is the one that needs 12v on key ignition. not wire number 3

 

no new suggestions today???

 

The .75 you see on the yellow/black SHOULD BE 12. You know this, I know this, ... great.
If you temporarily hook 12v to that yellow/black so it properly feeds the main relay 12v is what I'm asking for you to do. It is easy so let's make sure the rest of the system works so there are no surprises.

What is SUPPOSED TO HAPPEN is when you turn the key, the main relay energizes and two circuits complete. One of them is the fuel pump circuit. What is supposed to happen is 12v from the yellow/black (which you currently only have .75v) will connect to the black/yellow that runs to your fuel pump.

BTW: Ive already told you where to look for the actual .75 problem. I've never suggested you mess with the main relay by reflowing or anything... That's not necessary since you obvious have a voltage input problem on the yellow/black

 

there's two sets of yellow/black. one has two wires in one plug. thats the one that gets the .75v, wire 3. the wire that's supposed to get the 12v is the number 8, also yellow/black wire that gets ZERO voltage

 

Go read

http://www.tegger.com/hondafaq/mainrelayoperation/