Tach problem
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Junior User
Joined: Sep 2007
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Tach problem
I just installed a sunpro mini tach II in my truck and have some issues. At idle everthing is fine, but as soon as it gets to around 2400 rpms it will not go any higher. If I rev past it jumps to about 3000 when the engine gets there. If I decelerate it comes down as it should. Any ideas? Coil maybe. The truck is a 73 f-100 390
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I just installed a new tach in my truck. It ran backwards. It ended up being related to the MSD ignition sytem. Called them, and they sent out a set of resistors. Keep installing till one of them works. If you have an aftermarket ignition, call the tech line, they should help you out.
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Josh
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Returned the tach today and got a new one. This other tach does the same exact thing, hangs up around 2400, and once the get to about 31-3300 it jump up. It has a stock coil could this be the problem?
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Joined: Jan 2004
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From: Colorado
probably bad wiring. I was messing around when installing a tach in a truck, and wanted to see what it would do with improper / bad connections on the wiring and it did exactly what you are describing. Check all of your wires, the one going form the tach to the coil negative, the one that is keyed power, the one that is dash lights, and the ground wire.
2 new parts with the same problem is probably a problem with the wiring.
2 new parts with the same problem is probably a problem with the wiring.