Troubleshooting Electrical Bugs - refreshing ground connections
05-09-2004, 01:46 PM
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Troubleshooting Electrical Bugs - refreshing ground connections
Hello All,
Ref: 1983 928
From what I've read on the site, there are more electical problems than mechanical problems and after looking at the fuse box for the first time, I can see why.
Let me go from the specific to the general: I had a no-start condition. There was no fuel in the fuel rail. I assumed the fuel pump wasn't running; checked the fuse (ok); pulled the fuel pump relay and jumpered pin 30 (input voltage) to pin 87 (output voltage); still no response from the pump (even when the key was in either the "on" position or the "start" position with the engine turning. I jumpered a 12v wire and ground wire directly to the fuel pump and the pump was still non responsive ... so I believe the fuel pump is shot. If anybody has shopped around for a pump lately and found a good source that would recommend, I'd appreciate a reference.
But getting back to troubleshooting ... I disconnected the wired from the fuel pump and checked the voltage at the fuel pump (green-red and brown) and I found only 9.5V at the fuel pump. I guess it lost the 3V in the ground connection for the fuel pump.
Generally question ... is there a schematic or a diagram that shows all the physical locations in the car where wires are grounded to the chassis?
It seems to me that the first order of business is to clean and renew every ground connection in the car ... has anybody info on where to find that?
Thanks very much,
Tim
Ref: 1983 928
From what I've read on the site, there are more electical problems than mechanical problems and after looking at the fuse box for the first time, I can see why.
Let me go from the specific to the general: I had a no-start condition. There was no fuel in the fuel rail. I assumed the fuel pump wasn't running; checked the fuse (ok); pulled the fuel pump relay and jumpered pin 30 (input voltage) to pin 87 (output voltage); still no response from the pump (even when the key was in either the "on" position or the "start" position with the engine turning. I jumpered a 12v wire and ground wire directly to the fuel pump and the pump was still non responsive ... so I believe the fuel pump is shot. If anybody has shopped around for a pump lately and found a good source that would recommend, I'd appreciate a reference.
But getting back to troubleshooting ... I disconnected the wired from the fuel pump and checked the voltage at the fuel pump (green-red and brown) and I found only 9.5V at the fuel pump. I guess it lost the 3V in the ground connection for the fuel pump.
Generally question ... is there a schematic or a diagram that shows all the physical locations in the car where wires are grounded to the chassis?
It seems to me that the first order of business is to clean and renew every ground connection in the car ... has anybody info on where to find that?
Thanks very much,
Tim
05-09-2004, 05:37 PM
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http://members.rennlist.com/pirtle/zelec_cleaning.txt
Also search for Rennlist memeber Sharkskin. Once you find him, click on his webpage. He has a fantastic site detailing electrical maintenance.
Good luck.
Also search for Rennlist memeber Sharkskin. Once you find him, click on his webpage. He has a fantastic site detailing electrical maintenance.
Good luck.
05-09-2004, 09:19 PM
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Thanks for the plug, Rez. 
Actually it's the "Bzzzzt" section of my site and it doesn't mention all of the grounds, it's a detailed description of how I refurbished my fuse/relay panel. 
That link to John Pirtle's site would make a better "grounds checklist", no doubt about it.
Actually it's the "Bzzzzt" section of my site and it doesn't mention all of the grounds, it's a detailed description of how I refurbished my fuse/relay panel. That link to John Pirtle's site would make a better "grounds checklist", no doubt about it.
05-10-2004, 03:40 PM
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Tim;
The sites others have pointed you to have lots of good information on electrical system maintenance in general and ground cleaning specifically. I just wanted to add that the 928 Workshop Manuals (referred to on the board as WSM or repair manuals) have both wiring schematics that list the ground point relative general locations and photos of the ground points as well.
If you do not have the WSMs, search the archives for Jim Morehouse and you will find out more about where to get the CD version of same. Paper versions can be had from the Big 3 or eBay at various times, as they are general considered to be out of publication at this point.
I offer this info, as I stumbled around for awhile without the WSM and then again trying to find the source for the CD version. Thought I would save you the effort of doing the same.
Regards,
SteveCo in St. John's
The sites others have pointed you to have lots of good information on electrical system maintenance in general and ground cleaning specifically. I just wanted to add that the 928 Workshop Manuals (referred to on the board as WSM or repair manuals) have both wiring schematics that list the ground point relative general locations and photos of the ground points as well.
If you do not have the WSMs, search the archives for Jim Morehouse and you will find out more about where to get the CD version of same. Paper versions can be had from the Big 3 or eBay at various times, as they are general considered to be out of publication at this point.
I offer this info, as I stumbled around for awhile without the WSM and then again trying to find the source for the CD version. Thought I would save you the effort of doing the same.
Regards,
SteveCo in St. John's
05-10-2004, 04:47 PM
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Guys, thank you very much ... I really appreciate the help. I looked at all the links, did the searches, followed threads and have tried to get an inkering of what it takes to sort out some of these electrical glitches.
I have the WSM on a CD (I got it from a guy in the UK). I found the wiring schematic for the 83 and and I was amazed at how easy it was to located the electric fuel pump schematic. It is really well done. The problem is that the CD contains pdf files some of which are hundreds of pages long. It is really difficult to scroll through a document that long and get your arms wrapped around the scope of whats in there. Now that I know its in the WSM, I'll try to find that section on the CD.
Thanks again for the direction.
Tim
I have the WSM on a CD (I got it from a guy in the UK). I found the wiring schematic for the 83 and and I was amazed at how easy it was to located the electric fuel pump schematic. It is really well done. The problem is that the CD contains pdf files some of which are hundreds of pages long. It is really difficult to scroll through a document that long and get your arms wrapped around the scope of whats in there. Now that I know its in the WSM, I'll try to find that section on the CD.
Thanks again for the direction.
Tim
05-10-2004, 04:58 PM
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Tim;
The first few pages of each repair section in the WSM has list of repair groups and a table of contents for that section. I keep a printout of that handy to help me guesstimate the page number of the exact section I am looking for. Granted, it takes a bit of time to get used to the PDF page number vs. the WSM section/page number, but it does help speed up the process.
If you know someone with a copy of the Acrobat Creator, you could ask them to rejig the page numbers to match the format of the WSM or even add section markers to make navigation that much easier. Just food for thought. I think Mr. Morehouse's collection is section-ized and also text searchable....
Regards,
SteveCo in St. John's
The first few pages of each repair section in the WSM has list of repair groups and a table of contents for that section. I keep a printout of that handy to help me guesstimate the page number of the exact section I am looking for. Granted, it takes a bit of time to get used to the PDF page number vs. the WSM section/page number, but it does help speed up the process.
If you know someone with a copy of the Acrobat Creator, you could ask them to rejig the page numbers to match the format of the WSM or even add section markers to make navigation that much easier. Just food for thought. I think Mr. Morehouse's collection is section-ized and also text searchable....
Regards,
SteveCo in St. John's
