When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello everyone, I am new here but have a 95 Civic EX as my daily driver. It is completely bone stock and recently I started having problems with the car starting. I would listen for the fuel pump to prime, sometimes it would take a few seconds after turning the key, sometimes I had to turn the key a few times before it would prime. But once it primed, it started right up and ran great. This continued for several months and then I researched and bought a new Main Relay. The new relay gave me the same exact symptoms. Just this weekend, the pump stopped priming at all.
So troubleshooting, I thought maybe the pump went bad or the wiring was bad. I pulled the fuel pump out, jumped it to the battery, and it still fires up, so I know its good. I plugged a test light into the electrical connectors and got nothing. When I plug the test light into the main relay wiring harness, following the diagram below, I had power to pin 1 for the battery and pin 5 for the ignition. None of the other pins had power, even with the key on or cranking. I read other threads and tested the fuses 24 & 31 and both were good.
Can anybody help me out please? Thanks in advance.
It doesn't come on, even when the pump primes? Remove your cluster and replace the bulb.
With the key turned OFF, you should have voltage at pin 1, and only pin 1. With the key turned to ON(II), you should have voltage at 1 and 5 (as well as others, but let's stick with those two for now). Do you have voltage at 1 with the key off? Do you have voltage at 1 and 5 with the key to ON(II)?
Could be the ECU when the capacitors in the fuel pump priming circuit fail.
Common problem.
Borrow a known good ecu from somebody with a 93 - 95 civic for a test (P-28).
Check junk yards if you need a replacement about $125.
It doesn't come on, even when the pump primes? Remove your cluster and replace the bulb.
Aw man, you are adding to my list! Haha jk, I will do that sometime after I get it running again.
Originally Posted by NotARaCist
With the key turned OFF, you should have voltage at pin 1, and only pin 1. With the key turned to ON(II), you should have voltage at 1 and 5 (as well as others, but let's stick with those two for now). Do you have voltage at 1 with the key off? Do you have voltage at 1 and 5 with the key to ON(II)?
Just checked again, I only have power to pin 1 while key is off. When key is turned to ON(II) I have power to 1 & 5 but no others. Next step?
Could be the ECU when the capacitors in the fuel pump priming circuit fail.
Common problem.
Borrow a known good ecu from somebody with a 93 - 95 civic for a test (P-28).
Check junk yards if you need a replacement about $125.
Ummm . . . I dont know anybody with a car like this. Still a little new to my area. Is there any way to test the ECU? I pulled it out just to look at it today, it was clean and dry and everything looked good, but obviously that doesnt mean that it works.
no burnt spots or corrosion or leaky capacitors= usually good. crack open the relay and look for burn marks/cracked solder joints.
When I looked at it there didnt seem to be anything wrong. All solder joints were clean, no cracks. I know they are notorious for going bad at the solder joint, but when I put a new one in, I still had the same problem. Plus with not having power at the wiring harness, I thought that meant that my problem was somewhere besides the relay switch.
So you have power going in at 5, but not coming out at 8? That's indicative of a relay failure. Set your voltmeter test for resistance, and test between 5 and 8. What reading do you get?
If you're getting voltage at 5, then his ignition switch is fine.
Ok, so my battery died yesterday so I had to throw it on the charger overnight. After work I checked the car again, and when I plugged in the relay harness again I turned the key a few times and then the pump primed. The car runs now, but I know its only intermittent. Now I have power to pins 1, 3, & 5. With the key on, but no others. I didnt test resistance since it actually worked this time.
What do I do now? Can I still figure out what is wrong when it is actually working?
sounds like a loose connection somewhere if plugging things in/messing with the battery made it work
Well really its been an intermittent problem for the last month. Sometimes when I turn the key it wont prime, but after a few turns it will. Also the few times where it wouldnt start at all, I would come back after 8 hours and it would start right up. I have no idea what to do now.
So of course when I went to my car this morning, the pump did not prime and it wouldnt start. I didnt have any time to troubleshoot before work, but when I get home I am going to mess with wiring and see if there is a loose connection or something.
So I will check a local junkyard to see if I can find another ECU for a 93-95. Is there any other recommendations on where to buy one and how much it would cost?
So after checking this out again, I have noticed that whenever I put my test light on terminal 8 it engages the fuel pump. I guess because the test light is grounded? Im terrible with electronics . . .
So after checking this out again, I have noticed that whenever I put my test light on terminal 8 it engages the fuel pump. I guess because the test light is grounded? Im terrible with electronics . . .
All right guys, I am back at this again. I went to a junk yard today and got another ECM out of a 95 Civic to try. I have plugged it in and now the fuel pump is priming consistently every time and it engaging as soon as I turn the key. Success right?? Well apparently there is another problem now as the car still wont start. It will crank, so I loosened the bolt at the fuel filter and gas starting coming out, so that tells me I do have fuel pressure. And I just pulled all of the spark plugs and checked each one for spark. So I have fuel & spark, and the engine is turning over. Now I dont know what to check.
Install a new properly gapped spark plug into a disconnected to plug wire and ground the plug threads firmly on the valve cover. What color is spark? It should be bright white.
Install a new properly gapped spark plug into a disconnected to plug wire and ground the plug threads firmly on the valve cover. What color is spark? It should be bright white.
OK I will give that a shot. I did that with the existing plugs, but obviously they were older and im not sure if they were gapped properly. They looked like a yellow spark.
Originally Posted by RonJ@HT
CEL codes?
Well I think we determined that my CEL light is burnt out, so I still dont know if it has any codes or not. I have an OBDII scanner, but Im pretty sure this is OBDI. I just found the post on how to flash the codes so I will give it a try.
07-19-2015, 12:02 PM
95 Civic - Fuel Pump Wont Prime
