gas gauge question

[Don Jordan]

My gas gauge will go to full then like a switch was turned it will go off to empty. It doesn't come on all the time and doesn't stay on once it is on. I thought it could be the ground. I grounded it at the sending unit and under the dash. No change. I was looking at the schematic and it has a 1 and 2 but I don't know which is which. Could I hurt anything by just switching the 2 wires? I have an extra wire under the dash that is the same gauge and color as the one connected to the gas gauge. I can't find where that goes. I am just so frustrated. I don't know why I manage to keep having unique problems.

[captden29]

unique problems are part of this hobby. we all get them. sharing the solutions is what this forum does among other things. both my 54 windsors have gas gauges that do not work. I just use the odometer to track miles so I don't run out. if I were you I would not start switching wires or hooking up wires that may not belong there. often the sending unit is the problem, but like so many things in these old cars, the problem can be somewhere unexpected and elusive.   capt den

[_shel_ny]

I believe that if you look real close that the terminals are numbered at both ends. They must be connected correctly for proper operation of the gauge. That may not be causing your problem. It will not hurt to swap those 2 wires. That being said, I am not responsible for the results

 

You can eliminate the wiring as a cause of the problem by unhooking the existing wires at both ends, and running a couple of long wires from the gauge, out the door, and back to the tank for a temporary test.

[Old Ray]

unique problems are part of this hobby. we all get them.

 

Yes, yes and more yes !!

 

You can eliminate the wiring as a cause of the problem by unhooking the existing wires at both ends, and running a couple of long wires from the gauge, out the door, and back to the tank for a temporary test.

 

Yes, yes and more yes !! What he said.I

 

I wouldn’t be hooking up random wire unless I knew where they went.

       

So maybe think about it this way, the gas gauge isn’t, it is a meter that measures the amount of resistance in that circuit, the fuel sender isn’t, it is a variable resistor that is adjusted by the float. The “power” flows backwards from what you would think, through the gauge measuring the amount of resistance from the sender and then to ground.         

 

 

[Don Jordan]

I got a volt meter with really long leads. I'm going to run a continuity check and see if all the wires match. I just swapped out the gas gauge and the next step will be to take out the sender. One thing at a time. I know from my experience it's going to be something small.

thanks for the input.

[Don Coatney]

Has your gas gauge ever worked or is this a new issue? If new was any work done to the gauge system prior to this?

[Don Jordan]

Good question. When I first bought the car nothing worked. I spent a lot of time with cosmetics and mechanics so I never paid much attention to the little stuff. I drove the car north for about 600 miles and it worked off and on and I just lived with it. I switched the wires on the sending unit on Sunday and the gauge went to full. The car has not been running at its best so I haven't had a chance to go anywhere to see if it registers all the time. Right now I can't rule out the sending unit. If it comes down to it I will take the sending unit out of my other car and see if that changes anything.

[Old Ray]

 I spent a lot of time with cosmetics and mechanics

 

Sorry Don, I just can’t let this go by.  Would this be referring to cross dressing technicians?  

[Don Coatney]

Good question. When I first bought the car nothing worked. I spent a lot of time with cosmetics and mechanics so I never paid much attention to the little stuff. I drove the car north for about 600 miles and it worked off and on and I just lived with it. I switched the wires on the sending unit on Sunday and the gauge went to full. The car has not been running at its best so I haven't had a chance to go anywhere to see if it registers all the time. Right now I can't rule out the sending unit. If it comes down to it I will take the sending unit out of my other car and see if that changes anything.

The quickest way to having two non working gas gages is to remove the working unit from one car and install it on another.

 

If you do a forum search you will find several threads with information on what the ohm reading should be on your sending unit through the entire movement. I suggest you take logical troubshooting steps to correct this problem as opposed to blindly swapping wires and sending units as that most likely will create more problems than it will resolve.

[Don Jordan]

Merry Christmas. These old cars are going to be the death of me. I finally get it to run right and the gas gauge goes out. It will shoot up to full and then slowly go down to empty. Sit for a while and then go back to full. I have an extra gauge so I took it with a battery and hooked it up at the back of the car. Same result: goes to full then down to empty. Is there some sort of test to perform on the gauge to tell if it's working properly? I've done so many tests with the ohm meter that I'm at the end of whatever wit I had. Next step is to take the gauge out of the car that works and see if that will fix the problem. I just have trouble believing I have two faulty gas gauges.

I know it's Christmas but I would appreciate any feed back. - thanks

[Jim Yergin]

I am no expert but I would think it is more likely a problem with the sending unit in the tank. Maybe the float on the end of the arm has come off and the arm just swings up an down on its own. Had that happen on an old Mustang I once owned.

Jim Yergin

[Don Coatney]

I believe I gave my thoughts on the other thread about this same issue. In case you missed it my comment was

 

 

The quickest way to having two non working gas gages is to remove the working unit from one car and install it on another.

 

If you do a forum search you will find several threads with information on what the ohm reading should be on your sending unit through the entire movement. I suggest you take logical troubshooting steps to correct this problem as opposed to blindly swapping wires and sending units as that most likely will create more problems than it will resolve.

 

[Dan Hiebert]

Ditto on Don's and Jim's suggestions. I believe that would be the sending unit. I'd do the troubleshooting before swapping anything else out. Fortunately I've never had to monkey with mine, but I believe it is accessed through a small panel in the middle of the trunk floor, so you don't have to drop the tank.

Hey Don - sorry I missed you, but duty called. Major PITA getting back from the Thousand Islands today, but home safe and sound. Hope you have a great Christmas at your son's and I hope to catch you on a future trip.

[Don Jordan]

I swapped out the sending unit. Same result. Tomorrow I will swap out the fuel gauge. I just thought there might be a test I'm over looking. I just thought it odd that when I did a continuity check I got the same reading on both posts of the fuel gauge. Just doesn't seem right. Sorry to bother you guys.

merry Christmas all.

[55 Fargo]

Mrry Christmas. Not sure you have done the following, test both leads to sender unit from gauge, check hot wire to gauge itself, verify the gas tank grounded?

I would try this sender without installing, make sure all wiring and connections are good, tight and clean. If you have a spare gauge, bench test sender unit to verify.

Go with a systematic process of elimination. Good luck and keep us posted

[TodFitch]

If you've swapped the sender and the dash unit and still have the problem, I'd suspect wiring. If either of the two wires has a break or a bare spot that is occasionally connecting or shorting you will have problems similar to what you describe.

[Don Jordan]

It was the gauge. I put one in that I know works. It was that easy.