is this possible? gas guage....

[claybill]

i just got a new 40's car....drove it 10 miles and ran out of gas at 3/4 tank!!!!

i put 3 gallons in it and it is now 1/2 tank...??@?@??$%$?

is it possible for a gauge to read backwards? crossed wires or something.

maybe it is just a fluke...i 'll try it again.

bill

[rearview]

it's a metric gauge

[Jerry Roberts]

Yes , on a two wire sender the wires can be reversed and the reading will be backwards .

[BobT-47P15]

OK, Bill......now we want to know what this new car is. If you have already said, then I missed it. Yes, your wires might be backwards. You should be able to switch them on the top of the sending unit, rather than under the dash. Are the wires in good condition....no breaks or bare spots?

[Robin (UK)]

Has the car been switched to negative ground?

If so, maybe the owner didn't bother to sitch the fuel gauge wires.

What's the ammeter showing?

[Lou Earle]

the manuals for the 48 's hae info on what wierd reading means - like short or ground on a particular wire. I never have had many that worked all that well even when i had them then

[Plymouthy Adams]

try this:

[Young Ed]

My coupe gauge works fine. I removed the sending unit when I got it and dad helped me attach a new wire arm to it since the old one had rusted off with the float. Put a new float on there from my old dakota sending unit and away I went. All the gauges in that car seem to work great now.

[47heaven]

This fuel gauge is a never ending issue for me. I plan to troubleshoot this again, but just for the heck of it, why does my gauge always go past full (even when the tank is not full) and stay there as long as the ingnition is on? Is this a grounding problem? Crossed wires? Does anyone have the same behavior with their gauge?

[steveplym]

My gauge read the same way until I found out one of my wires were damaged and #1 was open. My new motto is "If in doubt, run new wires and check it out".

[steveplym]

This fuel gauge is a never ending issue for me. I plan to troubleshoot this again' date=' but just for the heck of it, why does my gauge always go past full (even when the tank is not full) and stay there as long as the ingnition is on? Is this a grounding problem? Crossed wires? Does anyone have the same behavior with their gauge?[/quote']

Does it ever move any lower than full at any time? I had the same problem and turned out to be a grounding problem.

[47heaven]

Does it ever move any lower than full at any time? I had the same problem and turned out to be a grounding problem.

No...it just stays all the way past full, without movement, until the ignition is shut off.

[Reg Evans]

Mine in my 40 Plym is doing the same thing. It's a 2 wire unit so I tried switching the wires around. Same f-in thing.

[steveplym]

No...it just stays all the way past full' date=' without movement, until the ignition is shut off.[/quote']

That is exactly what the gauge in my p15 did before I made a ground wire that attaches to the sending unit. It was placed between the sending unit rubber gasket and the unit itself, just used a round connector and used one of the sending unit bolts. I ran this wire down to the frame. Also replaced both wires running to the gauge as well.

Originally had Roberts rebuild the gauge and bought a sending unit from them several years ago. Up until a few weeks ago I had the same problem. Thankfully, due to some help I got on here I was able to fix it.

Good luck!

[Al Martin]

Hi Guys.

In my car (Dressed up P 20) my the polarity has been switched from 6 volt +ground to 6 volt -ground.

My Gas & Temp gauges is not working.

Only the Amp and Oil is.

Cold the ground swith have made the Gas & Temp gauges not to work.

And do any of you know where to get a working 6 volt wiper engine.

Please help.

Al Martin

[Plymouthy Adams]

You original temp gauge is mechanical..

The fuel gauge..should not be a problems as it is current driven device versus voltage..so polarity should not matter....I know on the two wire sender these will work + or - ground and 12 or 6 volt..they hve a 5 volt regulator built into them..

[Don St Peter]

No one has yet mentioned that if all checks out otherwise, the guage may need to be calibrated by using the procedure of para 13 page 130 of the Ply. service manual. I had very similar problems of mis-indication untill doing the calibration. Now it is right on.

Don

[47heaven]

That is exactly what the gauge in my p15 did before I made a ground wire that attaches to the sending unit. It was placed between the sending unit rubber gasket and the unit itself, just used a round connector and used one of the sending unit bolts. I ran this wire down to the frame. Also replaced both wires running to the gauge as well.

Originally had Roberts rebuild the gauge and bought a sending unit from them several years ago. Up until a few weeks ago I had the same problem. Thankfully, due to some help I got on here I was able to fix it.

Good luck!

The wires were replaced already so I know they are good. I also tried to run a wire from the sending unit to a part connected to the frame in the trunk. I still didn't see any inprovement.

Now, for the record, where exactly are you connecting this grounding wire onto the sending unit? There are two terminals, which I labeled A and B. A is positive and B is negative. I assume that I connect it to B or does it matter?Also, how I'm understanding you is that the grounding wire is connected between the head of one of the terminal screws and the gasket, not the gasket and the tank. Is that correct?

Also, where exactly did you ground the wire to on the body?

Just so you know...my P15 is now 12v neg ground. I also have a 12v to 6v reducer connected between the gauge and the hot lead.

Let me know if I'm understanding you right

[Young Ed]

A & B aren't positive and negative. They both go to the gauge. Your ground wire should go from one of the screws that holds the sending unit to the tank to a good ground.

[47heaven]

You original temp gauge is mechanical..

The fuel gauge..should not be a problems as it is current driven device versus voltage..so polarity should not matter....I know on the two wire sender these will work + or - ground and 12 or 6 volt..they hve a 5 volt regulator built into them..

Tim, a while back when I tried to run 12 volts straight through to my gauge, it started smoking. If you say that the gauge can handle 12v, then why did it smoke? Was my 5v built in regulator not working?

[steveplym]

A & B aren't positive and negative. They both go to the gauge. Your ground wire should go from one of the screws that holds the sending unit to the tank to a good ground.

Yeah that is correct. If you run a ground wire to #1 or #2 terminal screw that will create a different problem.

The screws that hold on the sending unit onto the tank is where you want to connect the wire and run to ground. Pick any of those and run down to the frame, clean off the paint where you connect it too for a good connection.

I drilled a hole in the bottom of the frame rail and connected the wire there, ran it up through a hold I drilled in the trunk floor.

Be sure to place the ground at the sending unit between the unit and the gasket, not between the gasket and the tank.

[47heaven]

Yeah that is correct. If you run a ground wire to #1 or #2 terminal screw that will create a different problem.

The screws that hold on the sending unit onto the tank is where you want to connect the wire and run to ground. Pick any of those and run down to the frame, clean off the paint where you connect it too for a good connection.

Okay...just confirming here...so the ground wire runs from one of the sending unit mounting screws and it needs to be in between the screw head and the gasket and not the gasket and the tank. Correct?

My question is if this is what needs to be done to get it to work now, how come it wasn't done like that originally or was it?

[Plymouthy Adams]

Darin..I was not there to observe..I have no clue as to why your gauge may have smoked. Proper connections are paramount in testing/calibrating this device. I have tested these devices on the bench and found them to be accuarate with both voltages..the only observation is that with 12 volts the heat cycle of the regulator is quick to open slow to close and you may see the slight flicker in the needle during this time. It takes about 5 cycles to indicate full deflection of needle and about 15 seonds to see it start to return after power is off 12 or 6 volt application. Further these can be calibrated right in place for full scale deflection and rest positions. The built in regulator coupled with the two coils that pull in opposite direction at the same time as driven by the moving wiper across the sending unit resistor is what makes these gauges slow to rise and rock steady reading even over the Baja Desert should you chose to enter yor car.

Further I understand from an earlier post that your dropping resistor is of the Runtz style and might I add will not effectively drop the voltage for the gauge and IF the load were such that it would, it will still allow surge voltage way above your 7.2 volt normally seen by this circuit as designed by the manufacturer. This surge will been seen every time the circuit is closed by the regulator contacts...say couple times a minute minimum.

[steveplym]

That is correct.

I know that my tank has been painted as well as the mounts, etc. My understanding is that originally the ground came from the tank itself, but after painting the tank, etc. the gauge lost its ground. This is a way to replace that.

[Reg Evans]

Tim,

Would you please come over here and fix all my malfunctioning gas gauges. I'm gettin kinda tired of all the unexpected journeys on foot.