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Registered
Join Date: Aug 2020
Posts: 109
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12.5v at battery only 2.5v in engine bay?
My 76 911s conked out on the drive this morning after starting fine.
The MSD and BitzEFI megasquirt aren't showing their usual array of led flash. The fuel pump also doesn't stop after 5 seconds. The starter motor operates fine n strong and other 12v circuits seem fine. The multimeter is only showing 2.5v at the fuse carrier and small red wire (msd ignition key circuit) in the engine bay. What could cause a low voltage? Cheers! |
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05-07-2021, 06:36 AM
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Somewhere in the circuit you speak of is a parasitic point of resistance causing a voltage drop.
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1980 911 - Metzger 3.6L 2016 Cayman S |
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05-07-2021, 07:23 AM
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ROW '78 911 Targa
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Could be a loose screw at the front fuse panel on the switched red power wire that runs back to the CDI and rear fuse panel. (Originally Fuse 11 counting back from headlights)
Or, Could be a bad jumper on the back of the fuse panel between fuse 11 and 12 too. Check voltage to both is the same with ignition on. (12 feeds 11)
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Dennis Euro 1978 SC Targa, SSI's, Dansk 2/1, PMO ITBs, Electric A/C Need a New Wiring Harness? PM or e-mail me. Search for "harnesses" in the classifieds. Last edited by timmy2; 05-07-2021 at 10:55 PM.. |
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05-07-2021, 09:47 PM
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Join Date: Aug 2020
Posts: 109
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thanks, now sorted. PO added a 'new' earth to the RH firewall however it wasn't fully back to metal. Took it apart, cleaned it up and now have the 12v plus back at the MSD and MS1 so both now behaving and no obvious lasting damage! Cheers folks.
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05-08-2021, 01:40 AM
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Heinz
