Do this test and make sure that there is dielectric grease under ignition module and screws are tight also check ground from battery to engine as well as ground wire from rear of cylinder head to body and battery to body ground. Do these tests that i'm sending. If it's a short in tach or tach wire it may do what you are experiencing. Otherwise I have no further suggestions.
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Wednesday, December 16th, 2015 AT 6:54 AM