chandler58

1992 Honda Civic LX L4 - 1.5L 1493cc type D15B7 - MFI SOHC

got it to start with starter fluid but wont run. changed fuel pump no go. new relay still no. fuel pump doesn't prime. made jumper wire for pump and it work. CEL stays on. will the relay not work if ECM goes out? How could i test if ECM is at fault? If its the relay how can i test it? i did return new relay cause it didn't help. I have multimeter.

Battery died so i will buy a new one. What should i start with when I get it?

Thanks for any help.

delsolintegra

Could be ECU borrow one and try it.

Was the problem getting worse on rainy mornings ?

Moisture/condensation slowly deteriorates ECU circuit board in cars this old and it seems to kill the starting circuit.

Hondaguy83

Try new ecu and look for loose or open circuits. Get a wiring diagram

Hondaguy83

Before doing all that check the fuse. They tend to go out

bandit67

With the new relay in do you have 12 volts dc at the fuel pump ? Have you put 12 volts straight to the fuel pump and was assured it pumps? I think the fuel pump relay gets power on terminal 5 and sends it to the pump thru terminal 7. Check that out to be sure and if so, do you have power on 5? And YES, you did check the fuse first didn't you......

boostedxcivic96

If you checked all the fuse an nuthin is working then if u have not tried a new ecu, look at the ecu an see if your capacitor for the fuel pump is blown on ecu, if so an If you have doone soldering befor an kno you can then replace the cap, i had that problem an took me two days to figure it out i got a 2nd ecu an 4 months later my 2nd p28 stop running turned out the cap blew on that one to i sat down an replaced them now both work, wont hurt to take a look and see good luck man keep us updated

jdmem205

iTrader: (2)

Where do you look at in the ecu if the cap is blown in other words where is it located?

Hondaguy83

https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/checking-main-relay-pics-2535047/
That's for a 91 civic but
. Test relay for power and ground. Two wires going from relay to ecu. Ones power and others ground.g
Check to see power is going to your ecu from the relay.
Check to see CPU is grounding the relay,if it doesn't then u must have a bad ground or defective ecu . Please check contuinity of all wires before replacing parts.

91integraLSVTEC

i had this problem before on my DA. dead ecu was my problem.

delsolintegra

With my 93 del sol si auto it was the bad ECU that caused the fuel pump not to prime. I replaced the ECU with a used one and have been good for over a year.

I still have the old P28 ECU and tried to find info on possibly fixing it.
I think it's the A7 pin that operates the fuel pump but i don't know what capacitor or diode on the circuit board is in this circuit loop.

Visually I can't tell, I don't see any bubbling or burnt item on the circuit board.

Is it fixable or worthless?

HondaPartsHero

Check your thermostat ground


If its good check this

boostedxcivic96

on ecu board its c14 near the front of the ecu were you plug it in, an also try taking a wire an cut in to ur main relay ground an ground it off u door hing ive have that problem, then you can track back an you know its the ground

Hondaguy83

Go strait to a7 n test ground if it doesn't ground its a bad ecu or bad ground.

delsolintegra

Thanks man. I know a guy who is a excellent solderer and I think I'll have him changeout C14. Is there any other item on the board that he should look at ?

boostedxcivic96

that's the only one i ever had to replace on mine but id replace all capacitors to be safe there like $1.50 for one so wont be to bad to replace them all

sir2ya

I got the same problem right now, will definitely do all the troubleshooting posted here and I will def, let you know what it was. Hopefully is not the ECU.

chandler58

Thanks for the response. I will give it go.

chandler58

where could i borrow an ecu? its always rainy here.

chandler58

looked at the ecu and everything looked fine. Not saying that aint the problem but i dont know hot to test the ecu.

Hondaguy83

Open wire from relay to fuel pump thru pin 7 output on fuel pump relay.
Test power and relays grounds. This should be simple

sir2ya

try everything here, so ended up taking the ecu out and drying it with a blow dryer. started in no time. Now I need a way to make it water proof. The ECU cover had some corroded and water spots.

97_ek_coupe

As all the above posts said, ecu. Same happened to me, started like a champ with ecu from junkyard

chandler58

So I figured out how to test relay. It was bad. Bought a used one on eBay for $20. Popped it on, and voila fuel pump primed and car started. Thank you for all your help and confidence that I could do it myself. Aloha.

chandler58

update. so i put everything back together and car dont start again. it has something to do with the ecu blue/white wire going to relay. unbolted ecu again fiddled around with the wire and fuel pump now primes. im leaving it out as is cause it works. is this wise?