I have a 1993 Accord ex-r that has been sitting in my garage for a short while. I jumped it about 2 weeks ago when changing my stat, and it started up no problem first try.
When i went to jump it again about a week ago, i mixed up the jumper cables and crossed the terminals on the batteries. Needless to say, my car wouldnt jump.
At first i would get absolutely no reaction from my car. I tested my battery - it is ok. I replaced a blown 80A Battery Fuse in the engine compartment, and now i have power to my car, but the engine just cranks and cranks and doesnt start.
It seems to me that my fuel pump is not starting up when i turn the ign on, i dont hear any kind of whirring. I personally don't think that its the pump itself, but i could be wrong. I have been accusing my main relay.
I have been reading thru my Hanes Manual, many forums online, trying all the test etc that i can and am not having luck.
When i do the continuity test, (hook battery up to terminal x and y and check for continuity at a and b) i never find any voltage, but when i initially hook the battery up to the relay it clicks a couple of times. Does that make sense, or am i maybe doing the test wrong?

I guess my biggest question is what kind of damage will likely result from my criss-cross jumper cable fiasco? If the battery fuse blew would it have ended there and not gone any further downstream? is the main relay the likely next victim? could it have reached my fuel pump?

Any feedback is greatly appreciated.

 

I just fixed the main relay in my 1992 Accord EX-R. Not sure if that is your problem, but here is what I did.

My Accord one day would not start, but it would crank, it acted like there was no spark or no fuel. Never had that problem before. So I left it in the garage and decided I would not drive it anywhere until I fixed the problem. Over the next few days I tried starting it several times and it always cranked but sometimes it would start, and sometimes it would not. So it looked like it might be an erratic electrical problem.

I previously had a distributor problem 5 years ago causing no spark and I suspected that might be happening again, so I wanted to make sure the spark plugs were getting power. I pulled off a spark plug wire and connected it to a spare spark plug that was grounded with an alligator clip wire, and I tried to start the engine. During cranking in a dark garage I saw a normal spark at a slow regular rate. So it looked like the engine was getting spark.

I could have next checked for fuel pump flow but I did not do that, that can be done by pulling out one of the fuel injectors. I was also considering removing the back seat to check the fuel pump power connector located there to see if voltage was present during starting, but I did not do that either.

I did some internet searching and decided the main relay was suspect. I watched the engine indicator lights during an attempted start and the check engine light (looks like a engine icon on my car) did not go out and there was no normal relay click sound from under the dash, and I did not hear any little sounds from the fuel pump in the gas tank. Before a normal start with the key in the position just before "START" the check engine light will come on and then go out after a second or 2.

After this, I removed the main relay from its normal location and got it to dangle from its connector (a LOT of work) and tried to start the car while watching to see if any of its circuit board connections were sparking, indicating bad solder joints on the circuit board. No sparks seen. Then I unplugged the relay and looked at the solder connections on its circuit board. The solder looked good. But then I used a magnifying glass and I could see a tiny circular crack around 2 of the soldered pins. I resoldered those and a few other connections that looked like they did not use enough solder. I plugged in the relay and SUCCESS the engine reliably started many times over the next few days. I think the car is now fixed, but I will not drive it very far for a while, in case the no-start problem comes back.

If you decide to check out the main relay, be careful when working under the dash, I cracked a rib while laying across the driver door sill to work in that area. The sill can put a lot of force on the ribs. I used some cushions but I guess they were not thick enough. After that, I removed the drivers seat so I could have more room to get under the dash. Even then it is very hard to work under there if you are 5'10" or bigger. I had to use just one hand most of the time.

When I put the main relay back, I left it out of the original plastic box that is bolted under the dash. I left it hanging there but secured by a wire between the clutch and brake pedal brackets. That is because I wanted the relay easily accessible if it malfunctions again and I need to repair or replace it. Also the relay should not get very hot there because of air circulation. When the relay is in the normal plastic box location it can get very hot after an hour or so because of heat building up and not allowed to escape, and that is probably what caused the solder joints to partially melt and go bad.

 

Thanks for the input Frank. I did re-solder a few points on the relay circuit board that looked a little suspect and have still had no luck. I also installed brand new spark plugs as part of my process of elimination, and that hasnt seemed to help. Granted, I have not tested the spark plugs to see if they're getting spark, which i will do next just for the sake of it, but that wouldnt solve my issue of not hearing the fuel pump start up.
I'm tempted just to install a new main relay to see what happens, but it's $80 and non-returnable haha so i'm trying to rule out any other solutions/confirm with reasonable certainty that the relay is the issue.

Thanks

 

test the input and output of the main relay. if there is no power going in then you have an issue with the wiring or ignition switch. If there is power going in and not coming out, it's the relay. if you have power in and out and still no pump, check the pump wiring under the back seat. if you have 12v to the pump and still no pump. It's the pump or pump assembly wires.

Where you say you tested it as described in the manual, what did it tell you to do if you found no voltage?

 

The tests i conducted weren't from my manual, but ones i found online, i think mainly from this message forum as well as a couple of youtube videos. here is an example https://honda-tech.com/honda-crx-ef-...-pics-2535047/ (every test i found seemed to be the same). is this what you mean when you say to test power in and out?

i'm a fairly intelligent guy but not a genius when it comes to electrical or cars, especially not when you put those two together. The diagrams confuse me a little because they show an image of a relay and a schematic of a relay, but the relay terminals are numbered one way on the schematic, but then the image has them numbered in a different order. Also on some of the youtube videos and diagrams, the colours of the wires don't match exactly with what's on my harness, which i assume doesnt really matter but just makes it a little more confusing.

 

ok so i found a good page with some tests: Main Relay Fix, Troubleshooting (Honda, Acura) and how to solder
i carried out the three relevant tests and here are my results (in order in which they appear on the page):

Harness test(?)
I had voltage on all 3 checks, but the odd thing was with the second check, terminal 2 (ground) to terminal 5. My voltmeter seemed to show a negative voltage here? (dial moved backwards). I got good voltage when i used the body as a ground instead of terminal 2, but using terminal 2 as ground worked fine on the other two checks...?

Relay Bench Test
Did not find continuity on any of the three checks. maybe im doing it wrong? i'm using a voltmeter as my "continuity checker" and getting no reading on it. If my voltmeter method seems legit, that probably means the relay is bad? confirmation?

Main Relay Circuit Test
i did not test #2 or #8 because i'm a little uncertain as to how i check for a ground... i also didnt check #6 cuz i cant hold my voltmeter and press the clutch in and turn the key to 'start' on my own...
#1 and #5 had voltage, but #7 did not. The page where this test is from says that #7 is the fuel pump circuit, which would make sense given the fact that i cant hear my fuel pump start up when i turn the car on.

Does anyone think that there is enough evidence here pointing to a bad relay to spend $80 and hope it works?

Thanks

 

The cost of the main relay should not be quite that high, I looked on rockauto.com and for a 1993 Accord it appears to be $23.99 to $39.79 plus shipping, it looks like the same part used for my 1992. Rockauto calls it the fuel injection relay. I have never used rockauto but my friend uses them often for Volvo parts.

It would be an idea to check any fuses that might be related to PGM-FI, ECU, or fuel pump. On my car which is very similar there is a 10 Amp ECU fuse under hood in the main fuse box under the hood, and another 15 amp ECU fuse under the dash on the left. No fuel pump fuse seen on my car.

 

Check the relays ground, terminal 2 black, for continuity to chassis ground, must have full continuity, if not check ground lead(s) going to thermostat housing bolt. 94

 

the fuses were, of course, the first things i checked when trying to diagnose the problem. the only blown one i found was the 80A battery fuse in the engine which i replaced.

 

i have continuity from black(2) to my chassis, but only when the ign is turned on. hopefully that is proper? also, i have read in a few places that i should have a ground wire bolted to my stat housing, which is not the case in my engine. i DO however have a cable coming off the negative battery terminal bolted to the car body/frame/whatever just beside the battery. same thing different location, yes?

 

That ground should be there at all times, to test, run a jumper from that ground lead to chassis ground, just push a stripped portion of lead into the ground terminal on the PGM-FI Main Relay ground, black lead, and ground the other end.

Has the thermostat been replaced, was the ground left off?

" i DO however have a cable coming off the negative battery terminal bolted to the car body/frame/whatever just beside the battery. same thing different location, yes?"
It is not the same, that ground is the main batt. to chassis ground. 94

 

I tested the ground on my relay again, and still nothing with the ign off.

I did change the stat recently, but do not remember any wires whatsoever, so i took another look in my engine, and my battery has a cable coming off that splits. one cable bolts onto the frame right next to the battery (like i told you before) and i followed the other to... somewhere else on my engine, forgive me i dont know exactly what it is. the wire DOES look kinda messed up. the pic im attaching isnt very good but hopefully gives you an idea. maybe this blew when i mixed up the jumper cables? that could make sense as to why im not getting a ground without the ign turned on, and possibly the larger problem concerning my engine not turning over?
i have already ordered a new relay because it was reasonably inexpensive and was at a loss for solutions... i will check out lordco (my local auto parts retailer) to see about getting some new wire to replace this one.

 

Using a multimeter, test for ohms on each side of that piece of cable. It should be 1 ohm or less.

 

ummm so the reading seemed to vary depending on exactly where i held the probes, not sure if that's because of the condition of the wire or because the multimeter i have is a cheap analog piece of junk, but the short cable that is in good condition seemed to be between 1-0, and the blown cable seemed to be between 1-2. i also noticed that (along with the wire looking frayed) alot of the rubber casing to the blown cable seems to have been melted away

 

replace the negative cable then, it shouldn't have any resistance above 1 ohms

 

replaced the negative cable. again, not the highest quality mulimeter so im not getting exact readings, but doesnt seem to be much for resistance now when i test.
still not getting any volatage from #2 black on my relay to chassis with ign off, but getting voltage with ign on

 

received me new relay in the mail. still not getting voltage between #2 black and chassis until i turn ign on. still not hearing my fuel pump charge up or whatever, still no engine start.
going to remove my back seat and check out fuel pump wiring

 

It's entirely possible the ecu got damaged when you switched the battery cables.

The way the relay works is it provides power when the ignition is turned on. The power closes the circuit and allow power to the fuel pump. However the ecu still has control over the main relay. It may be damaged and not allowing the fuel pump to turn on.

You should remove it from the bracket and open it up and see if there is anything damaged or burnt inside.

 

thanks for the advice. i will take a look at the ecu today, as soon as i figure out where it's located.
i took my rear seats out and tested for power at the fuel pump harness. seemed to have anywhere from 8-12v with ign on.

 

This is a pretty comprehensive video on testing for voltage drop on a fuel pump.

 

interesting video, but it specifically states that the fuel pump has to be running, which is the problem im having with my car.
like i said, i will take a look at my ecu today, but could that really be the issue of the fuel pump?
i jumped #5 & #7 on my relay harness and did find voltage at the fuel pump harness. my Hayne's manual says that this points to a faulty fuel pump. i saw a youtube video of some random guy in his garage saying an easy/surefire way to test the pump itself is to remove it and basically hook it up straight to a battery to see if it works at all. does this seem legit? i already have my seats out so it wont take much more to remove the pump. i believe i can remove it through the access panel behind the seats.
also, i will take a look at the ecu today.
going to try to convince a friend who is a lot more car-saavy than i am to come help me today.

 

ecu board looks ok to me. not sure if i need to look for hairline cracks in the solder like when i was checking out the main relay, but there are no obvious signs of a short.
searching online for some tests that can be performed

 

just noticed this little 3-pin plug in my engine fuse box looked a little, off... can't really tell if it looks burnt or not, just kinda looks like its got some crud on it, but everything else around it is clean.
not sure what its for, but i found a diagram on google of a fuse box that looks similar to mine and based on that diagram, this might go to "main harness"? (C256)
can anybody confirm what this connector is and whether or not it looks blown?
on the one hand, im hoping this could be the simple solution., on the other hand, if it is, i'd be pretty frustrated with myself for not having found it earlier... (also sorry that my pics are all so big, i guess thats just the settings on my phone?)

 

so upon further inspection, the "crud" is a light coloured substance with the consistency of a lotion or something like that. seems strange. it seems to be all inside the connector

 

saw this in another thread: "You need a multimeter.

Unplug ECU connectors A and B. Test for continuity to body at A26, B2, A23, and A24 in the ECU connector. With the key in ON(II), measure voltage to body ground at A25 and B1 in the ECU connector."

i think i need a new multimeter because the leads on mine are kind of falling apart. i was getting continuity on A26 each time i tried, A23 & A24 i got readings half the time. in all cases, the readings were around 20 ohms. i didnt get anything from B2 any time but the prong on the connector is super small so im not sure if my multimeter lead even got in there.
i didnt get voltage between ground and A25 or B1.
i have seen diagrams that show two ways of numbering the pins, srtaight across and going up/down/up/down... i preformed the test using both numbering methods, and to be honest i get the same results either way.
I still have no idea where the ECU has a ground connection. ive been trying to trace the wires from the ECU but i kind of lose them between the dash and engine. it almost looks to me like those wires that are gunky might be coming from the ecu. could they be ground wires?
if im not getting a good ground to the ecu could that be the cause of all these problems?

i also tried jumping the 2-pin connector in an effort to get a code readout from my check engine light, but the light does not flash, just stays steady on (tho semi-dim). would this by any means mean a code 0?