Completely at a loss....
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Completely at a loss....
For those of you sick of hearing about my fuel problems, trust me, I'm even more sick of writing about them. Here's what I did today:
1. Changed the AFPR to a new unit. Pressure holds steady now with no power to the injectors (harness unplugged).
2. I connected both sides of the injector harness, one at a time an pressurized the system. Both banks of injectors (again, only one side powered up at a time) emptied the fuel load of fuel delivered by the pump. To me, that's an incredible amount of fuel delivered by 4 injectors from a 255 lph pump.
3. I checked all of the injector harness wires that are visible and accessible and found nothing wrong; no wires rubbing metal or otherwise showing distress.
Now I'm at a loss. Clearly the injectors are grounding out. I was wondering if perhaps there is a circuit in the ECM that might have been compromised?
I really don't know what to do or where to go from here. Thanks guys for all of the input so far. Hopefully I can get this sorted out ('cause I really want to go out and smoke those new 315-35 GS-C's I just bought!!!)
1. Changed the AFPR to a new unit. Pressure holds steady now with no power to the injectors (harness unplugged).
2. I connected both sides of the injector harness, one at a time an pressurized the system. Both banks of injectors (again, only one side powered up at a time) emptied the fuel load of fuel delivered by the pump. To me, that's an incredible amount of fuel delivered by 4 injectors from a 255 lph pump.
3. I checked all of the injector harness wires that are visible and accessible and found nothing wrong; no wires rubbing metal or otherwise showing distress.
Now I'm at a loss. Clearly the injectors are grounding out. I was wondering if perhaps there is a circuit in the ECM that might have been compromised?
I really don't know what to do or where to go from here. Thanks guys for all of the input so far. Hopefully I can get this sorted out ('cause I really want to go out and smoke those new 315-35 GS-C's I just bought!!!)
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Originally Posted by MrNuke
Damn . I hope it's as 'simple' as something shorting out and causing your havok. Electrical problems always suck bigtime.
Hope you find it chief.
Hope you find it chief.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Unplug the ECM and the injectors, turn ign on , monitor the fuel pressure, plug each injector in one at a time and watch the fuel pressure. One or more that causes a sudden drop has a short to ground on the wire that goes back to the ECM. If fuel pressure drops rapidly with no injectors plugged in, then you have one or more injectors with a coil that is shorted to ground inside the injector. If no injectors or wiring has a fault, then plug the ECM in and see if the fuel pressure rapidly drops and if it does, you have a defective injector driver on the ECM board.
Last edited by jfb; Jul 27, 2006 at 12:29 AM.
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Originally Posted by CorvAdel
With all of the electrics connected, and with ig. on, did both banks of injectors dump heaps of fuel? ie did all 8 inj's open right up?
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Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Originally Posted by jfb
Unplug the ECM and the injectors, turn ign on , monitor the fuel pressure, plug each injector in one at a time and watch the fuel pressure. One or more that causes a sudden drop has a short to ground on the wire that goes back to the ECM. If fuel pressure drops rapidly with no injectors plugged in, then you have one or more injectors with a coil that is shorted to ground inside the injector. If no injectors or wiring has a fault, then plug the ECM in and see if the fuel pressure rapidly drops and if it does, you have a defective injector driver on the ECM board.
Thanks for the good info.
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Originally Posted by AGENT 86
If both banks fired, i would start looking at the ECM. jfb's advice should help you sort this out.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Originally Posted by jfb
Unplug the ECM and the injectors, turn ign on , monitor the fuel pressure, plug each injector in one at a time and watch the fuel pressure. One or more that causes a sudden drop has a short to ground on the wire that goes back to the ECM. If fuel pressure drops rapidly with no injectors plugged in, then you have one or more injectors with a coil that is shorted to ground inside the injector. If no injectors or wiring has a fault, then plug the ECM in and see if the fuel pressure rapidly drops and if it does, you have a defective injector driver on the ECM board.
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
Problem Solved!!!
Woohooo! The ECM injector driver was bad. I dropped in my spare ECM, and it all looks good; pressure is holding!
Thanks to everyone who read along and respoded to my issues!
This place is great!!!
Thanks to everyone who read along and respoded to my issues!
This place is great!!!
Racer
Joined: Nov 2004
Posts: 445
Likes: 0
Originally Posted by RRT vette
Good thing you had that spare ECM. Sometimes we do all the work thinking "it can't be the ECM", but sometimes it is.
Congrats silver86
Congrats silver86
This took a lot of patience, time, perserverance and some humility in asking for help.
Well done for hanging in there and nailing it!
Many others would have given up a long time ago and paid big bux to have some-one else fix this..
...and how good is this forum...!
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
It was just blind luck that I had that spare ECM. It came with the intake, runner, plenum set that I bought used off of Ebay and just happened to be the updated replacement for the 86 ECM. What are the chances of that?
Naturally, I broke a plug as I started putting everything back together again, but that I can certainly handle.
Again, thanks to everyone who went down this road with me; it was surely appreciated.
Naturally, I broke a plug as I started putting everything back together again, but that I can certainly handle.
Again, thanks to everyone who went down this road with me; it was surely appreciated.