 Tach wire at coil kills engine |
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| surfdogskier |
 May 18 2020, 05:42 PM
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#1
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Member  Group: Members Posts: 164 Joined: 20-May 16 From: East TN Member No.: 20,019 Region Association: None  |
Hey Guys,
So none of my needle gauges are working. Well, the tach does sort of. I turn the key and it buries all the way to the right. I know the purple/black wire from the coil should be going to the Tach. When I connect it to the negative side of the coil, my engine dies. I can't even start it with it connected. When I disconnect the wire from the coil, she fires right up. So, is my tach fried or something else. My speedo does not work or my gas gauge. However, the illumination lights work and the signals, high beam lights on the gauges. Looking for answers. Thanks, Jason 1972 1.7, carbed. |
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| GregAmy |
May 18 2020, 06:32 PM
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#2
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Advanced Member Group: Members Posts: 2,296 Joined: 22-February 13 From: Middletown CT Member No.: 15,565 Region Association: North East States 
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You sure you have it connected to the correct side? The tach goes to the "1" terminal, not the "15".
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| Spoke |
May 18 2020, 06:59 PM
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#3
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Jerry Group: Members Posts: 6,978 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None
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Disconnect the wire at the tach and see if it does the same thing. I had a similar experience and removing the tach wire at the distributor allowed the engine to run normally.
I disconnected the wire at the distributor and measured its resistance WRT to chassis and got a very low resistance (short). Disconnected the engine harness from the relay board and still got a low resistance. For some reason, the wire in the engine harness was shorting to ground. Ran a new wire from the distributor to the relay board connector and all was fine. |
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| jim_hoyland |
May 18 2020, 08:01 PM
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#4
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Get that VIN ? Group: Members Posts: 9,287 Joined: 1-May 03 From: Sunset Beach, CA Member No.: 643 Region Association: Southern California
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Could the tach wire be grounding out ? I had one do that
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| Beebo Kanelle |
May 18 2020, 10:02 PM
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#5
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Member Group: Members Posts: 248 Joined: 22-November 12 From: Houston, Texas Member No.: 15,177 Region Association: Southwest Region
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Its either one of two things: either the coil is wired backwards or, the tach is wired backwards
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| surfdogskier |
May 19 2020, 08:54 AM
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#6
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Member Group: Members Posts: 164 Joined: 20-May 16 From: East TN Member No.: 20,019 Region Association: None |
Thanks for the input guys. I will tinker with it this evening and post back with my findings.
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| VaccaRabite |
May 19 2020, 01:02 PM
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#7
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En Garde! Group: Admin Posts: 13,442 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
Yup, if you ground your coil from the TACH wire you will get no spark and the motor will immediately die.
Zach |
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