Tachometer problems
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Tachometer problems
Hi, I have a 87 f250 with a 6.9, the tach sits on 0 when the truck is not running when started it goes backwards to 4200 redline I already replaced the sensor at the injection pump. (help) Thanks in advance.
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I have a '91 with a similiar problem, except perhaps even more erratic (sometimes goes backwards like you describe, sometimes just goes really fast forward, way faster then the engine is actually revving). I also replaced the sensor, since that is apparently what usually goes out, and I tried to trace for shorts, but to no avail. Current thinking by my mechanic is that its the actual tach in the dash, but since that is ~>$300 and I usually shift by ear anyways, I haven't replaced it.
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Joined: May 2004
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From: Prince George, B.C.
It is possible that the Tach in the dash is doing this but I should also ask, how are the other guages functioning? A tach from the wreckers should be cheap.
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I don't know about Lil Abner's but all the rest of my guages work just fine. I haven't pursued used tachs, but probably will. I think its a pretty rare failure, so a used one should be a good risk.
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Iam also in the same boat with bbbranch just joined this forum no email privleges.My main concern for the tach is it sounds like my engine is revving to much before shifts ,(c6 auto) shifts at 27mph and 48mph 3:54 axle is this normal thanks
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(glad mine's a stick) 
If its affecting the shift points, then I would *think* that its more then the tach in the dash. Unless the trans is getting its info from the tach, but I would think it would be taking it from the sensor directly, which you've already replaced... hmmm...
Hopefully some smarter person can help you out
If its affecting the shift points, then I would *think* that its more then the tach in the dash. Unless the trans is getting its info from the tach, but I would think it would be taking it from the sensor directly, which you've already replaced... hmmm...
Hopefully some smarter person can help you out
Post Fiend
Joined: Nov 2004
Posts: 5,638
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From: Manitoba
Lil Abner do a signature re the info about your truck..... go to Quick links at the top and put all the info you can........ we all refer to that info for correct answers to your problems as there are several different systems for different years......thanks.