Welcome to the North American Subaru Impreza Owners Club Monday May 10, 2021
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Electrical & Lighting

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 02-20-2021, 02:36 PM   #1
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default STi swapped GC: no CEL, no fuel pump, everything else works

Hi everyone,

Trying to fix my swapped GC one last time before I send her to the scrapyard.

Hit a bump and the motor died, turns out it was one of the SBF's under the hood. Threw a new one in, fired right up but blew again in under a minute. Threw a solid wire bridge just to get home but it melted the wire instantly.

got home replaced the SBF again, car ran for a few seconds then died.

Now only the fuel pump relay clicks, but dont hear the fuel pump acually turning on.

No CEL at all. Main relay is not clicking, not sure if it is triggered by the ignition, or by the ECU. Subaru wiring diagrams are **** so can't rely on them at all to diagnose anything.

Has anyone encountered the same issue? I swapped out all the relays in the car (20 of em!) and checked every fuse. Really don't want to spend 300 on an ecu when the scrapyard only pays 400 for the entire car.
* Registered users of the site do not see these ads.
guciodog11 is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 02-20-2021, 09:56 PM   #2
Cougar4
Scooby Guru
 
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
Winestone

Default

Check the wires by exhaust pipe manifold as see if there are burned harness wires.
Cougar4 is offline   Reply With Quote
Old 02-21-2021, 10:16 AM   #3
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

I already removed and inspected the entire engine harness, no burnt wires or shorts anywhere. Thanks!
guciodog11 is offline   Reply With Quote
Old 02-21-2021, 01:38 PM   #4
Cougar4
Scooby Guru
 
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
Winestone

Default

Was the fuse that was blowing out SBF-5? The main relay is controlled by the ECU so make sure all power sources to the ECU are good.

Last edited by Cougar4; 02-21-2021 at 01:45 PM.
Cougar4 is offline   Reply With Quote
Old 02-21-2021, 01:57 PM   #5
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

Yeah it was the IGN fuse. Not sure if it's called SBF-5 on a GC body but it blew a few times. It is fine now though I replaced all of them.

How can I check power to ECU? I hear the fuel pump relay clicking, but I cannot rely on wiring diagrams to determine if the fuel pump is switched on by the ECU or something else. The fuel pump is not turning on at all, regardless of fuel relay status.

EDIT: http://www.northursalia.com/modifica...04_STi_ECU.pdf
According to this, are pins 19, 5, and 6 supposed to be hot on ignition on? They of course didn't include of power is coming into or out of these pins ugh

Last edited by guciodog11; 02-21-2021 at 02:05 PM.
guciodog11 is offline   Reply With Quote
Old 02-21-2021, 02:39 PM   #6
Cougar4
Scooby Guru
 
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
Winestone

Default

The pin numbers you stated don't make sense to me for power. Lets see if power is getting to the fuel pump relay and out of it since you say it is working. Power goes into the relay on the blu/red wire and out on the blk/yel. Verify power is on those wires while the relay is ON.
Cougar4 is offline   Reply With Quote
Old 02-21-2021, 02:42 PM   #7
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

Sorry, I meant pins 19, 5 and 6 on connector B135 labeled as control unit power supply, and backup power supply.

I'll check this out in a bit, I appreciate the assistance!
guciodog11 is offline   Reply With Quote
Old 02-21-2021, 03:40 PM   #8
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

Just tested it out. My wiring color is different, so i based it off this: https://imgur.com/vHgE6AH
1995 impreza wiring diagram

With ignition off, Yellow/Green was hot

With Ignition on, Yellow/Green, BlackRed, and Yellow were hot.
For some reason LightGreen/Black had 25mV instead of zero.
guciodog11 is offline   Reply With Quote
Old 02-21-2021, 03:47 PM   #9
Cougar4
Scooby Guru
 
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
Winestone

Default

The low voltage you saw is just the ground connection to activate the relay. Most ground connections will have a little voltage drop on them when they are active.

Since voltage is good there then check the voltage at the pump connections. If the input voltage at the pump is low then there is a problem in the wire connection between the relay output lead and the pump input lead connection.
Cougar4 is offline   Reply With Quote
Old 02-21-2021, 05:13 PM   #10
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

Quote:
Originally Posted by Cougar4 View Post
The low voltage you saw is just the ground connection to activate the relay. Most ground connections will have a little voltage drop on them when they are active.

Since voltage is good there then check the voltage at the pump connections. If the input voltage at the pump is low then there is a problem in the wire connection between the relay output lead and the pump input lead connection.
Made some progress just now! Turns out I only bought a spare main relay, I did not replace it. Swapped out the main relay and checked the contacts. Interestingly, when the ign is on, the relay clicks, connects the 2 switches as expected. however when key is removed, the relay does not deenergize!

Fuel pump controller and fuel pump is energized upon ignition, however it sounds very "rough", as if it were not getting enough juice to it. Cranking is fine however it's apparently not getting any fuel. Havent checked coil voltage yet, I don't have anyone to help me today.

My guess that it's some sort of grounding issue?
guciodog11 is offline   Reply With Quote
Old 02-22-2021, 06:35 AM   #11
Cougar4
Scooby Guru
 
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
Winestone

Default

There may be a slight delay for the relay to turn off after the ignition is turned off. Check the voltage getting to the pump motor and make sure it is getting 12 volts. If that is good then you may need to replace the pump. I doubt there is a ground issue.
Cougar4 is offline   Reply With Quote
Old 02-22-2021, 01:41 PM   #12
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

Thanks for the help! I'll check it out if the snow ever melts in NY
guciodog11 is offline   Reply With Quote
Old 03-19-2021, 06:06 PM   #13
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

Swapped out the fuel pump with a brand new Aeromotive 340. ECU has power, throttle body whines when in on position but still no start. Threw in a new crank position sensor still nothing....

I swear, Subarus make BMWs seem like the most reliable cars in the world. Im about to burn this pile of **** to the ground.
guciodog11 is offline   Reply With Quote
Old 03-20-2021, 12:14 PM   #14
Cougar4
Scooby Guru
 
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
Winestone

Default

You can spray some starter fluid into the intake to see if that helps fire up the engine. If that helps then check for voltage getting to the fuel pump motor while cranking the engine to see if the pump is getting power. You should be able to hear the pump turn on briefly when turning on the ignition but not the starter.
Cougar4 is offline   Reply With Quote
Old 03-21-2021, 08:20 PM   #15
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

i smelled gas around the intake mani so I'm fairly positive it's getting fuel.

The pump clicks on for 1-2 seconds when IGN on however it's quiet, MUCH quieter than the walbro it replaced.

Still might need to replace the cam position sensors. Other than that I have zero clue what the issue might be.

Thanks!

Here's a screenshot of Romraider, max values are during cranking.
https://i.imgur.com/p3HWZKF.png
Coolant temp sensor is working, as is crank position (RPM). injectors are firing, throttle body opens without a problem, battery voltage is also good.

Last edited by guciodog11; 03-21-2021 at 08:56 PM.
guciodog11 is offline   Reply With Quote
Old 03-21-2021, 09:26 PM   #16
Cougar4
Scooby Guru
 
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
Winestone

Default

Here are the questions you need to ask yourself and verify they are working...
1. Do I have spark?
2. Do I fuel getting to the cylinders?
3. Do I have proper compression in the cylinders?

I assume you have verified that you have spark. You haven't proved, to me at least, that fuel is getting to the cylinders. The easiest way to verify that the engine still won't start with a added fuel is to spray a small amount of starter fluid into the intake to see if that makes a change. If that doesn't cut it then you need to check compression and the valve timing.
Cougar4 is offline   Reply With Quote
Old 03-22-2021, 09:53 AM   #17
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

Haven't checked compression, although car was running fine before electrical issues. I'll check nonetheless.

Can I just take the coil pack connector off and check the pin voltage? I hope it's still 12v instead of whatever voltage the plug itself needs. Made the mistake of disconnecting ign wires once when I was a kid and that wasn't fun.

Ill pick up some starter fluid soon and give it another try.

Also, is there some sort of ignition relay separate from the one that provides power to sensors and ECU?


Thanks for your help!
guciodog11 is offline   Reply With Quote
Old 03-22-2021, 12:41 PM   #18
Cougar4
Scooby Guru
 
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
Winestone

Default

You can check the voltage on the ECU pins going to the coil while the ignition is ON and the resistance while the ignition is OFF. I believe there is an ignition relay used in models before the year 2000.
Cougar4 is offline   Reply With Quote
Old 03-22-2021, 01:37 PM   #19
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

Checked 1995 wiring diagrams and didn't see anything for ign other than the main relay. The harness merge probably switched things around since it went from a distributor to COP. Ill do some more digging hopefully today.
guciodog11 is offline   Reply With Quote
Old 03-24-2021, 09:53 AM   #20
guciodog11
Scooby Newbie
 
Member#: 160264
Join Date: Sep 2007
Chapter/Region: Tri-State
Location: S.I, NY
Vehicle:
95 20G'd EJ255 GC8

Default

Ok boys and girls, whoever is reading this thread and has similar problems, learn from my stupid mistakes!

PSA: It helps to connect your fuel rails the right way. The fuel pressure regulator goes on the RETURN side not feed!

Motor is happy and purring loudly now

Thanks Cougar4 for putting up with my BS and helping me to get up and running!
guciodog11 is offline   Reply With Quote
Old 03-24-2021, 08:12 PM   #21
Cougar4
Scooby Guru
 
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
Vehicle:
2001 LL Bean Outback
Winestone

Default

You're welcome for the help and glad you found the problem.
Cougar4 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 12:18 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2021 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.