Fuel guage not working properly and charging system also

quote:

My fuel guage ('74) is only reading just over half full when I fill up the fuel tank. Any suggestions to remedy this? The tank was out of the car and painted. Could it be just a case of dirty connections or a bad ground?

Hi Steve,

Yes, it could be dirty connections or a bad ground. Try a jumper from the tank's ground terminal to a good ground. Other possibilities are the fuel sending unit, float catches on something in the tank, fuel gauge, or wiring. See the wiring diagram and other info in this thread:
http://pantera.infopop.cc/eve/...0077274/m/2871090216

quote:

Also, my charging system does not seem to be charging the battery. The guage reads in the plus when the engine is running however the brand new battery goes dead. When the headlights are turned on even when the engine is not running the guage also reads in the plus rather in the minus as a draw on the system.

Sound like the charging system isn't charging, and the wires on the ammeter are reversed.

You can take your alternator and have it checked. Does the GEN light in the tach work when the key is turned on without the engine running? If it doesn't light, the white (IIRC) wire that feeds it may not be connected (should have 12 volts with the key on), or the blue wire may not be connected to the light.

Check these items and report back to us.

John

Hi John,

re:

(You can take your alternator and have it checked. Does the GEN light in the tach work when the key is turned on without the engine running? If it doesn't light, the white (IIRC) wire that feeds it may not be connected (should have 12 volts with the key on), or the blue wire may not be connected to the light.)

Thanks very much! I checked the blue and white wiring and they were not even hooked up! I would have never thought of that! Also, the Ammeter was also hooked up backwards as you suggested.

As for the fuel guage:

(Yes, it could be dirty connections or a bad ground. Try a jumper from the tank's ground terminal to a good ground. Other possibilities are the fuel sending unit, float catches on something in the tank, fuel gauge, or wiring. See the wiring diagram and other info in this thread:
http://pantera.infopop.cc/eve/...0077274/m/2871090216)

I did as you suggested with the ground and cleaned all connections. The wiring diagram that I have shows a yellow wire going to the fuel guage - (I have found a "stray" yellow wire near it not connected to anything) - but the fuel guage has no connection for that yellow wire. It is still not working properly so I guess the next step is the sender.

On another note:

I have an aftermarket distributor - NOT MSD - in the car and I would like to get the Tach working. Would I have to use an MSD Tach adaptor or would it even work with this distributor? I think it is Protronix or something like that. (a cheap one anyway)

Thanks again,
Steve

Hi Steve,

Does that mean that the charging system is working, and the ammeter is reading correctly?

The fuel sender should have one yellow wire and one white/black wire. The white/black wire is for the quantity, and the yellow is for the low fuel warning light. Make sure that you have the correct wire connected to the correct terminal on the sender. Review the wiring diagram again. There could also be a wiring error at the fuel gauge. What color wires are connected to the fuel sender?

Connect the tach wire to the negative terminal of the coil.

John

Pantera-Steve, Wilkinson recently reproduced the '73-up fuel gauge sender, which fits all Panteras regardless of year and is cheaper & much more available than in the past. All the vendors now have this in stock. The OEM sender assembly (plastic case, resistence wire and slider attached to a long wire float-arm) can fail in numerous ways- all virtually unrepairable.
One more thing you CAN check before writing a check is whether the float has become fuel soaked and thus doesn't 'float' on top of the fuel anymore. Used floats are available from most of the vendors as well.
To easily remove (or work on) the sending unit, first remove the left-side rear quarter window assembly. It does NOT bolt in- the only thing holding it in place is friction between the body and the rubber gasket (and maybe some paint overspray). A large flat-blade screwdriver will pop it right out. Then remove the engine screens and the sender will easily slide out the opening. Trying to horse a sender out & back in between the roof & tank will almost guarantee damaging something.

Hi John,

RE:

quote:

Does that mean that the charging system is working, and the ammeter is reading correctly?

The fuel sender should have one yellow wire and one yellow/black wire. The yellow/black wire is for the quantity, and the yellow is for the low fuel warning light. Make sure that you have the correct wire connected to the correct terminal on the sender. Review the wiring diagram again. There could also be a wiring error at the fuel gauge. What color wires are connected to the fuel sender?

Connect the tach wire to the negative terminal of the coil.

>Yes, the charging system is now working, but the ammeter bounces around a lot. I understand that this is common for Pantera ammeters to do.

>The fuel sender has just the yellow/black wire on the guage. Under the guage pod there is a yellow wire not attached to anything but the guage does not have a location to attach it. (no prong). On the sender both the yellow/black wire and the yellow wire are connected properly as per the wiring diagram. The guage seems to be wired correctly.

>Thanks for the tach wiring info also!

>And Bosswrench, thank you also. If I can't get the fuel guage accurate enough then I will check out the vendors as you suggest.

>As I stated before, the car came in boxes and the tank has had no fuel in it for at least 8 yrs but as far as I know, the sender was never out of the tank.

Steve

The yellow wire connects to a light at the gauge. It needs to be a lamp socket with two connections. One side is power from the ignition switch and the other side is the yellow wire which completes the ground at the sender when the tank is low. The float arm is probably hanging up on the baffle inside the tank.
Forest

Hi again,

Finally had the time to get back at it.

The fuel guage is still not working.

re:

[quote]One more thing you CAN check before writing a check is whether the float has become fuel soaked and thus doesn't 'float' on top of the fuel anymore. )

I have pulled the sender out of the tank. The float does not seem to be fuel soaked at all. I hooked the wires up to the sender while I had it out of the car - held in my hand - and watched the guage. I moved the float slowly through its entire movement and the guage worked all the way from empty to full. As soon as it is put back into the tank it only reads max. half full. (I had just filled the tank with gas so I know that is not a problem). The sender assembly was originally installed about 180 degrees around so I copied the location from my 72 Pantera and installed it the same way. It does not hang up on any baffles in the tank - I checked several times while installing it. I am baffled!!!

Any more suggestions?

Thanks in advance,

Steve

Try it outside of the tank in a bucket of fuel.

Anybody have a picture of what wires go where?

I have black, yellow and a white/black wires.

I have two terminals on each side of the pickup (one towards the driver, one towards the rear of the car), and one ground terminal attached to the sender body.

Thanks in advance.

Rocky

Chuck,

This should help.

John

John -

That's exactly what I needed to see. I got the black wire right!

Thanks

Chuck

I had the exact same problems recently and they traced it to a short in the steering column.

The charging system was gooing dead and the gauges would all either read incorrectly or all go blank.

The local electronics shop fixed it for 240.00.