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924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
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Posted: Wed May 06, 2020 9:49 pm Post subject: |
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Yeah, those 1000 and 1500Ohm wires are the ballast resistors/wires.
Definitely confine your investigation to the wires to and from the relay. Odds of a new relay being NFG are low, if not zero. Testing all the leads should resolve the issue.
If that pesky green/white wire has zero resistance to the tach and coil as shown on the wiring diagram, that should be enough.
One thing I'm not completely certain you've checked: can you verify you have +12V on relay terminal 15 when ignition switched on, and a good ground on pin 31 of the relay at all times?
In addition to needing the tach signal, those are the control circuit for the relay; very easy to have a break there.
Finally, might also help to share pics of the wiring diagram printed on the side of your fuel pump relays (both original and replacement) - make sure those are correct and match the wiring diagram... _________________ Vaughan Scott
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winddude
Joined: 15 Jan 2020 Posts: 61 Location: Vancouver Island
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Posted: Thu May 07, 2020 4:05 am Post subject: |
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924RACR wrote: |
One thing I'm not completely certain you've checked: can you verify you have +12V on relay terminal 15 when ignition switched on, and a good ground on pin 31 of the relay at all times?
In addition to needing the tach signal, those are the control circuit for the relay; very easy to have a break there.
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I get 9.6v from 15, the ignition terminal with ignition on. I get 1.2v from the tach signal with ignition on. |
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winddude
Joined: 15 Jan 2020 Posts: 61 Location: Vancouver Island
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Posted: Thu May 07, 2020 4:11 am Post subject: |
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Original relay, I believe, and the replacement KAE 3.300.300
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924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
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Posted: Thu May 07, 2020 4:26 am Post subject: |
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winddude wrote: |
I get 9.6v from 15, the ignition terminal with ignition on. I get 1.2v from the tach signal with ignition on. |
But what about the ground? _________________ Vaughan Scott
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'82 931 Plat. Silver
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winddude
Joined: 15 Jan 2020 Posts: 61 Location: Vancouver Island
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Posted: Thu May 07, 2020 9:36 am Post subject: |
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The ones near the relay board are a little corroded, I'll have to work on getting in there to clean them. However I was checking voltage off of that ground terminal.
Engine to body is a little corroded might need to be replaced.
Also interesting battery to body, goes battery to engine...
The green and white wires I have <1ohm between the coil and relay board and tach and relay board. |
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924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
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Posted: Thu May 07, 2020 9:31 pm Post subject: |
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Definitely clean your grounds before going any further. _________________ Vaughan Scott
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'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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winddude
Joined: 15 Jan 2020 Posts: 61 Location: Vancouver Island
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Posted: Wed May 20, 2020 6:44 am Post subject: |
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cleaned all the crounds, and terminals on the back of the relay panel. That was a big job on hooking all of them and getting them back up.
I did resolve the issue. I had the tach hooked up backwards... opps. Working now. |
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924RACR
Joined: 29 Jul 2001 Posts: 8815 Location: Royal Oak, MI, USA
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Posted: Wed May 20, 2020 8:41 pm Post subject: |
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Good job! Well done... _________________ Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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