Have a 91 Dakota with a tachometer jumping around like crazy. Driving the other day it suddenly went nuts, and felt like maybe there wasn't the power like there should be. Thought maybe the transmission was slipping or low on AFT. So checked while idling (seemed low, so added 1/2 qt before realizing may not have seated the stick solidly). Checked today, really full.

Drove about 10 12 miles, it was only the last mile that the tachometer started jumping again, although this time I didn't notice any shifting problem.

So any ideas? I'm not a mechanic, and don't really have one. Anything I can do? Is it going to hurt to drive it while it's jumping around? The engine doesn't sound like it's revving when the needles is jumping around.

Thanks

 

There is a lot of people who have this problem. Its normally the cable that runs from the tachometer down to the transmission. Once they wear out, they tend to nuts. Try a search, there is a lot of info in here.

 

I did a search first, but my question wasn't addressed. Is it going to hurt anything or cause problems if I drive it like that?

 

I get this too sometimes. Still running a couple months later...

 

Whew! Okay, thanks.

 

Your thinking about the Speedometer, it shows the speed.

She is talking about the Tachometer, it shows the RPMS.

 

Hate to tell you this Crazy4x4, but I do know the difference between a speedometer that shows how fast I'm going, and a tachometer that show RPMs; different both in look and function.

My question was about the tachometer. I was driving 45 miles per hours when the needle on the tachometer began jumping wildly between 2 and 8 (x1000).

 

I don't know how well this is going to relate to your problem, but I used to have a 90' Civic that had the same problem; turned out to be a bad cap and rotor. So maybe start there. Pretty cheap to replace.

 

Really? Definitely a place to start, probably need to be replaced anyway.

Uh, what "cap"? I know rotor...oh distributor cap. Got it. I can do that. I think. Replaced both in my old Datsun years ago.

Thanks

 

If you saw who I was quoting, I quoted oxygen454, so my statement was to correct his statement. He stated that the Tach is cable driven. The Speedometer is cable driven not the Tach.