The fuel, oil, and temp gauges on my 81 f250 share a common trait: they are inconsistent, together. When one reads low (more often than not), all three read low. I suspected and cleaned contacts at the cluster connection and ignition switch, with no (consistent, of course) effect.
These gauges share a common path through a voltage regulator (bolted to the back of the cluster) which seems to be a permanent part of the printed circuit. Could this regulator be the source of the problem? How can I test it? Can it be replaced, and how?

 

yes the regulator(CVR) is defintly your problem. it is bolted to the printed circuit,carefully remove printed circuit connector, it just snaps on the regulator and remove the 1/4" head screw.have replaced many for this same problem

 

It just snaps on the regulator? Are they all like that? I tried to disconnect mine, but the connections seemed permanent. I didn't pry any harder for fear of breaking it. Is the regulator something I can get at the auto parts store, or a dealer item?
Oh, yeah, thanx for the response!

 

only place i've got them is at dealer. the "ribbon" of the circuit board just lays on the CVR and snaps in place at two places, mabye try removing screw first then try to disconnect it

 

be careful

 

Before replacing.... Thoughly clean the contacts and tighten the regulator contacts
to the foil trace and to each other.

 

Will do, will follow up. Thanx.

 

Bought an instrument voltage regulator (IVR) today, $20 (I know the guy at the counter). Installed it and the fuel/temp/oil gauges would not work at all! I fussed with things a bit and eventually got the gauges working but no better than before, at best.
I've tested the printed circuit and IVR connections with volt and ohm meters, and everything seems fine. If I unbolt and remove the IVR from ground with the engine running, the fuel gauge will peg and the temp and oil gauges will read high. From this and other tests, I'm satisfied the cluster is well-grounded through the wiring harness.

According to my 77 factory manual, the IVR is supposed to put out an average of 5 volts, and it is adjustable - the book doesn't say how, but there is what looks like a small **** on the unit which may be there for that purpose. Before I stumble through this myself, does anyone have any input?

 

Gettin' deeper into this. I disassembled the new unit today (btw, it's a borg-warner r306, I believe) (an incredibly simple and cheap device, must have a profit margin of 1,000%). Here's the news: it appears to be adjustable. There is what looks like a small **** next to the output connection - if you turn it clockwise with a set of needle-nose pliers, you will increase the closing tension on the points inside. If your gauges are reading low (like mine), you may be able to increase current to them, which should raise (???) their readings. If you try this (I haven't yet, I'm not an authority on this, do not know the proper procedures ), go slow and use a volt meter to measure output. According to my factory 77 shop manual, output should be an average of 5 volts.
Sidetrack - The reason for the rinstrument voltage regulator is to drop voltage from 12-14 to 5, which is the operating level of Ford fuel, temp, and oil gauges since the early '60's..
Best news: you can build your own SOLID STATE regulator with cheap stuff from Radio Shack. This is what I'm going to try, and the reason why I'm not (wasting time) adjusting the stock regulator. I believe forum rules prohibit me from refering you to another website, so just do a search for "ford instrument voltage regulator", and look for the words "solid state" and "turbotbird" in one listing. You'll find required materials, written instructions and photos. It looks good to me! Will build and follow-up within 7 days.

 

good luck,will be interested in what you come up with. I'm an retired Ford tech(35yrs)
so i have had a lots of experience with Ford gauges and cvrs, i must say of all the many i have replaced i never had one that did not fix the gages for your symptom.
you got one on me. never to old to learn

 

Hedgeapple! I read the article. Tired of buying CVR's at 30 bucks a pop I too will drop by Radio Shack and pick up the parts to build this IVR. I cannot see clearly the circuit for the 5V output as it relates to the resistor. The directions seem to show the resistor connected between the output post on the regulator and the ground? Any electronic experts out there who could shed some light on this? I could see if the resistor was installed in the 5V leg between the source and load. But connecting it across from the output to the ground would create a short circuit (resisted)? The parts are cheap and I have plenty of burned up CVRs so I guess I'll just experiment. I also plan to mount the resistor outside the case on the plastic insulator so it will operate a little cooler.

 

IT WORKS! IT WORKS! Built and installed the sucker today. I'd never soldered anything in my life, but I followed the verbal instructions I got from the salesman at Radio Shack (right here in Newton, KS), and IT WORKS!
My gauges still read low, which means 1) the new unit quite possibly DID work (what can I say, Gary B.?); and 2) my gauges need adjustment (initial factory adjustment may've been done at too high a voltage? Or perhaps I've damaged them?). At any rate, I'm going to research gauge adjustment/calibration.
william, the resistor does indeed connect the output (5v) to ground. I grounded it, along with the regulator's ground, under the screw (6x32, w/nut and lockwasher) I used to attach the regulator to the case. It helped me to view pictures 7 and 8 (three total) full size.
In contrast to the instructions, I put the screw head inside the case and the nut outside. You'll know why when the time comes for you. I did grind off the exposed theads flush with the nut, and taped over the result with electrical tape to protect the printed circuit. I also bent the mounting bracket so that the nut would clear the printed circuit altogether, and enlarged the hole in the dash (plastic) behind the regulator to avoid pressure on the regulator.
Folks, If you can learn to solder and are willing to follow the given directions carefully and slowly, you can do this. It took me three hours, and I can take a 30 minute job and knock it out in 5 or 6 hours, just like that. If you already have a soldering pencil, resin-core solder and flux, the remaining items required may cost $10. Compare that to $30 at the parts house IF you're lucky, or $68 list at you Ford dealer.

 

great,glad to hear it works. very interesting, there must be something else there but it works and that is the main thing. hope i was a little help.Gary

 

Well, you got me moving. thanx!

 

hedgeapple! Excellent! Good job and thanks for posting back! That resistor business was driving me nuts!