Tach and fuel guage stopped working......?

The tach may be toast. There are glass resistors in a small circuit board inside, and I've found at least two tachs with cracked components, opening the circuit. If you can borrow a known-good tach, try it; if it works, that's the problem. A good speedo repair shop might be able to fix a bad tach, or you may find a used one affordable. Pantera and Mangusta tachs are identical.

Regarding the fuel sender, there is a curved wound-wire potentiometer as part of the sender inside the tank. The wire is very thin and sometimes breaks as the contactor rubs across the turns. The late sender is still available at the vendors, is not outrageously expensive and fits your early car's tank perfectly. The late assembly includes a fuel-out line built-in, fixing the two main tank problems in the early car: rust pinholes in the welded tank line that does not allow a full tank to be drawn into the engine, and a plugged and inaccessible filter-screen on the end of the welded line inside.
The simplest way to replace the sender is to first remove the left rear quarter window which is only held in place by friction of the rubber gasket to the body. A flat blade screwdriver can be used to carefully pry the whole window and chrome frame loose. On a few cars, the left 'gill' overhangs the window frame and must be removed before the window assembly can be removed. And sometimes, repaint overspray glues the edge in where imperfect masking was done.
Next, remove the engine screen cover and the left solid engine cover. This exposes the fuel tank top and sender wires. Mark the wires and disconnect.
Unscrew the ring of screws holding the old sender in, and lift it up and out the opening left when you removed the window.
THe new sender goes in reverse of the removal. I suggest plugging the old line and transfer the fuel line to the new sender fuel-out pipe. This all sounds complicated, but the entire operation is a matter of maybe 30 minutes, once you've done it a few times. Many of us remove the glass from the chrome frame and only replace the frame. This allows easier fuel tank/sender/wiring trouble-shooting in the future, and it's much easier to clean the big vertical rear window. Having the glass in place does nothing for or against the aerodynamics of the Pantera.

Wont they start working in the spring when you wake the cat up from its hibernation?

Check your fuel sensor (get a wiring diagram)on mine bk/white stripe is the gas gauge needle 0 ohms is full 200+ ohms is empty unplug the wire and ground it to a good ground and look at the fuel gauge if the needle moves the meter is good and so is the wiring to it.

Next pull the sending unit out (Jack is right pulling the quarter window is the best way but) on my 74 #6656 you can get the unit out of the gas tank if you do it carefully.

On mine the sending unit float sank (Bennet Auto Supply $19 universal fit Sunpro Gas sending unit float is very close if you want one now), the vendors sell the correct float. I have no idea about the tach and why both would quit at the same time. I will look at my diagram and if I see something I will reply again... good luck

An important consideration. Did these anomalies crop up at exactly the same time?

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An important consideration. Did these anomalies crop up at exactly the same time?

Yes, I parked the car for the winter. It sat for approx. 1 month inside in my shop, (everything worked fine when I parked it), then it was a sunny day so I took it out for a drive last Sat. and both the Tach and fuel guage had stopped working at the same time. Got me baffled. I must admit that I know next to nothing about wiring etc.
Thanks

As another addition to this: The battery was disconected for the entire time. I have checked all wires on my wiring diagram and everything is as it's supposed to be.

FWIW, trying to pull the sender out of a gas tank by fitting it between the tank & roof usually causes bending of the float arm. I have TWO senders here that broke at the sharp bend entering the rheostat, and dunno if its weldable. The float arm wire is a hardened type steel and does not tolerate much (sometimes none at all) bending.
Also, having the window out allows easier R & R of the large fuel hose that connects the outside gas filler to the tank. If you have a '73-up and yours hasn't cracked yet, know that its only a matter of time. Radiator hose will NOT work as a substitute- it needs fuel-proof hose.

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Originally posted by 72panterasteve:

quote:

An important consideration. Did these anomalies crop up at exactly the same time?

Yes, I parked the car for the winter. It sat for approx. 1 month inside in my shop, (everything worked fine when I parked it), then it was a sunny day so I took it out for a drive last Sat. and both the Tach and fuel guage had stopped working at the same time. Got me baffled. I must admit that I know next to nothing about wiring etc.
Thanks

It would lead one to believe that the two would be tied to a single item failure then. They do share fuse #12, along with the other gauges. I would wiggle or replace fuse 12. Make sure the contacts are bright. Wiggle the wires on the back of the fuse panel at fuse 12 to burnish them.

Along with that, burnish up the ground contacts on the stud under the dash, just to the left of the speedometer. There is a big bundle of black wires that terminate there.

I go along with Dave. Two diffent failures with a common thread, fuse 12. Replace the fuse just to eliminate a problem fusethat looks ok.

When I had the OEM fuse panel, a glass fuse was intermittently broken inside the tip. It looked perfect & tested ok until I jarred it. Yours could be broken inside the tip of the fuse & open all of the time. Two problems & both powered by #12, start with the fuse & work backwards.

After you find the fix, replace the fuse panel with Pantera Electronics’ ATO fuse panel. It is so easy. Definitely worth it! Watch the demo: http://www.pantera-electronics.com/fuse%20panel.htm

The pink wire (from fuse #12) that is the +12v for the fuel gauge is also the +12v for the temp and oil gauges. If the temp and oil gauges work, but not the fuel gauge, check the pink jumper wire that ends at the fuel gauge. If ok, then trace back to the sending unit. It could be a bad ground at the fuel tank or a bad sender.

Fuse #12 also feeds the brake lights and the turn signals.

The tach is fed from the UNFUSED side of the #12 fuse. Check the wire connection on the UNFUSED side of the fuse block at the #12 fuse. The tach feed wire will either be white or light blue.

The GEN warning light (in the speedo) is fed from the tach +12v wire. If the GEN warning light illuminates when the ignition switch is turned on (RUN position), then the tach is getting +12v, although it may not be making a good connection on the back of the tach.

John

An update:

I got the fuel gauge working. It was just a coincidence that it stopped the same time as the Tach. The problem was the float had a pinhole in it and was filling up with gas, so I changed the float and hence - no more problem!

The Tach is another matter. I have now tried a second Tach from my other Pantera - same problem. Grounded it directly to the battery, checked and cleaned the #12 fuse as suggested, checked all grounds just in case, all connections are tight, and it still won't work at an idle but does as soon as I step on the gas and rev it up!??

I have a new distributor and coil - an aftermarket "ready-to-run". All wires are tight. Could it be a faulty coil with perhaps the primary circuit not working properly? I might add that the engine runs like a clock. Plenty of power and it never misses a beat. The resistor wire has been by-passed as suggested by the distributor manufacturer.

I am at a total loss as to what is the problem.

Steve

If you're running an electronic distributor such as an MSD, the std Veglia tach may be erratic or not work at all without a tach adapter. Is the engine using points 'n a coil as stock? The only known exception is the Ford Duraspark 2 electronic adaption; most tachs work fine with them.

I am running an electronic distributor, but not MSD.

The Tach worked fine for over four months with the distributor that I bought but has since acted up after putting the car away for the winter and starting it after approx one month in storage.

Do you know if an MSD tach adaptor will work with other distributors? Maybe that't the problem!?

Steve,

There may be a problem with the wire (or connection) that goes from the tach's negative terminal to the coil's negative terminal. It's kind of a pain, but you could try a jumper wire from the tach to the coil.

John

Glad to hear you got the fuel sensor working what type of distributor is in your car?

The distributor is a Pro Comp.

Dist and coil part numbers: PC 7004 and PC 2041

I've heard nothing but bad about anything with the name pro comp. As others suggested, recheck all the connections at the engine end of the circuit.

Being in the Electrical Trade connections are normally an issue oxidation happens. Look at or download the directions for the distributor to get a good start. I would remove and clean all terminations from the distributor all the way to the tach make sure you include the grounds, if you can't get to them plug and unplug a few times rub them with an eraser, scotchbright just get them clean. If it still does not work take an ohm meter and check the connections to make sure the wires are still good. I run the stock dual point in my car so all I can help with is the stock wiring that you can find on this site, or on Panteraplace.com. Good luck. One last thing if it worked when you parked it and you have not done anything it should work when you try it... if not the options are environment (oxidation) or heaven forbid creatures eating wires (happens in my trade a lot).

I think that I have narrowed the tach problem down to the distributor not putting out a proper signal at low rpm. Everything else seems to check out.

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Bennet Auto Supply $19 universal fit Sunpro Gas sending unit float

Anyone know which vendor if any has just the float? I checked out the websites and cant find it. Its for a 75 pantera. Thanks

As far as I know, ALL Panteras can use the same sender and float regardless of year. Practically any FIAT, Alfa or other such car dealers sell an identical float- I'd look for one from the early '70s to be sure. All the vendors likely have them but with such a small, cheap part, its not economical to advertise them. You'll actually have to call & talk to one or more. Junkyards sometimes don't even charge for floats; bring a set of small metric sockets.

Thanks Bosswrench...I will call some verdors to see if any have it. Small part but important. I can always try local cars parts great idea.

I received a fast response from a place in nevada...You can bake out the fuel in a closely regulated oven Or send it to me and I can do it for $50.00, or buy a whole new sender unit.

So I got around to replacing my fuel sender. Bad float, wires broken, sock gone. So it wasnt a big deal to install it. But, I know I have 3 gallons of gas in it ( I put 3 in today) and the fuel gauge red light is on and the needle is on E. If I unplug the wire for the light it will shut off, when I unplug the white/black and touch it to a ground the fuel gauge jumps to Full. I bought it from wilkinson. Is there something I am missing?

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