Tachometer weird
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Joined: Jun 2010
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Tachometer weird
I have a 1987 BII. The tachometer goes from 0 to about 1400 rpm at start up but won't change upon acceleration or decceleration except when you shut down it goes back to zero. What do ya think...mechanical or electrical problem? 
Cargo Master
Joined: Mar 2007
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From: Arcadia, Fla
Probly electrical related. Start by checking the wireing at the TFI modual and finaly back into the cluster for bad connections and grounds. My guess is the tach itself is failing if the wireing checks ok.
I forgot if the 87 had the older style tachs, my 89 B2 is the newer style. If yours is the older style, you may want to check the tach's circut pc board for yellow glue that is turning brown(it holds the pc board componets from vibrating) and starts conducting electricty which causes a wierd tach readings.
The 80 to 86 F-series tachs had this problem and I fixed a few by removing that yellow/browing glue and cleaning off the PC board with a circut board cleaner.
I forgot if the 87 had the older style tachs, my 89 B2 is the newer style. If yours is the older style, you may want to check the tach's circut pc board for yellow glue that is turning brown(it holds the pc board componets from vibrating) and starts conducting electricty which causes a wierd tach readings.
The 80 to 86 F-series tachs had this problem and I fixed a few by removing that yellow/browing glue and cleaning off the PC board with a circut board cleaner.
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Tachometer weird
Thanks for the response. The tach is connected to the circuit board in the instrument cluster. Haven't gone into it yet because of the work involved in removing the cluster. Will do as suggested about the TFI wiring etc. then if no success will check out the circuit board. Thanks again. 
