92 XLT tach problem (jumps to 3000 rpm)

[RinTX]

While this isn't exactly a "crisis," I'd like to get the dash back together ASAP, so if there is any sort of test I can perform to isolate it to the tach itself, I can start calling wrecking yards and get on it with it.

(NOTE - I added other search terms in () to make it easier for others to find, including "guage" because that's how some seem to spell it ):

The fuel gauge (gas guage) is not working, but testing it by disconnecting the pump assembly at the harness on the driver's rear frame by the tank indicates a problem in the pump assembly - it goes to "Full" when disconnected. I'm only including this info in case it might be relevant.

The tach (tachometer rpm) is doing the "jump to 3000" thing when the key moved to the on position - key on, engine off, prior to starting - and then remaining in the 3000-4000 once started, regardless of RPMs. I removed the tach, cleaned the cluster connection pins and tach-motor-to-circuit-board mounting screws, nuts, and pads, and reinserted it into the instrument cluster. Didn't fix it. I've found vague references to "a thing under the battery," etc., but nothing concrete. Any suggested tests, fixes, tips/tricks, anything? I can get a replacement at a wrecking yard, but I'd like to isolate it to the tach itself before I do this.

Thanks for any and all help.

 

[LBarr2002]

tach

It could just be that the tach is bad. I've gone through a couple dash panels in my 91, and my friend had a 91 bronco that the tach went crazy in too...they just don't last forever. In the bronco, when you stand on it the tach would just spin around the gauge, in mine if its over 3,000 rpm...sometimes it wraps around through 6000 and back to zero. If you have a way to just plug in a different tach and test it I'd do that.

I got a whole dash panel for $50 from a local junkyard...try that.

almost forgot...the float in my gas tank got a hole in it...sunk to the bottom of the tank, always read empty...is that your problem?

 

[Creager]

http://www.explorerforum.com/forums/showthread.php?t=129889

me and 410fortune answered your questions already

 

[1Byounkin]

I'm having the same problem with the same thing. Not working fuel guage and no tech. Stays at 6,000 rpms. Fuel guage same pass full. When key off the needle on the fuel guage moves to F but after you turn the key on the needle drops pass (to the right). The tech did the same thing started at 3,000 rpms than went to 4,000 (all without moving the gas petal) than final the needle on the tech drop to 6,000. Now stays there. If you rev the engine to about 3,000 (you have to guess) the needle will move up from 6,000 up to 5,000. Very slow movement, even letting off the needle slowly moves back. Engine runs great everything works, just not the things listed.