checking fuel sender

[Cornpatch MO]

My 64 Dodge project. guage does not work. Cleaned and coated the fuel tank and the sender cleaned but not checked . I made a ground strap for the fuel sender. Grounded the wire from the sender to the guage and no responce. I haven't got an ohm meter yet, but assumeing that the sender is ok. Then what is the next steps to check out. How do I make sure the wire from the sender to the guage is ok? Can it be checked out where it plugs into the printed circuit? It has been suggested that maybe my printed circuit is bad. I have installed a new electronic voltage limiter. Any help appreciated....................................MO

 

[Gpuller]

If you ground the sender wire your gauge should go to full if its good.
Not familiar with the '64 wiring.

 

[Cornpatch MO]

If you ground the sender wire your gauge should go to full if its good.
Not familiar with the '64 wiring.

I tried that, but still nothing..............Thanks...........................MO

 

[Gpuller]

I would say the gauge is bad if it wont go to full when grounded.

 

[Belle66]

I recently went through the same drill. I took the sending unit and with several alligator clip leads extended the cabling to where I could sit in the driver's seat and hold the sending unit. In this case it needs to be grounded. i then moved the unit from stop to stop and observed the needle on the fuel gauge in the dashboard. If you have a resistance meter you can see if you've got continuity through the sending unit and see if it changes as you move from stop to stop.

My car was reading low. So I used this method to adjust the resistance range and then the stops to get a better reading. Eventually the instrument cluster will come out again and I'll address the electrical issue back to stock at that time.

 

[Cornpatch MO]

I recently went through the same drill. I took the sending unit and with several alligator clip leads extended the cabling to where I could sit in the driver's seat and hold the sending unit. In this case it needs to be grounded. i then moved the unit from stop to stop and observed the needle on the fuel gauge in the dashboard. If you have a resistance meter you can see if you've got continuity through the sending unit and see if it changes as you move from stop to stop.

My car was reading low. So I used this method to adjust the resistance range and then the stops to get a better reading. Eventually the instrument cluster will come out again and I'll address the electrical issue back to stock at that time.

Good idea's. That would make sure wiring from sender to guage is OK..............................MO

 

[moparedtn]

I recently went through the same drill. I took the sending unit and with several alligator clip leads extended the cabling to where I could sit in the driver's seat and hold the sending unit. In this case it needs to be grounded. i then moved the unit from stop to stop and observed the needle on the fuel gauge in the dashboard. If you have a resistance meter you can see if you've got continuity through the sending unit and see if it changes as you move from stop to stop.

My car was reading low. So I used this method to adjust the resistance range and then the stops to get a better reading. Eventually the instrument cluster will come out again and I'll address the electrical issue back to stock at that time.

Excellent.
Wish I'd have "calibrated" my sender before installing in the tank...
Oh well, at this point (and after more than one attempt), at least the dang thing doesn't leak anymore.

 

[Torkmnstr]

The grounding gauge is a sure sign if your gauge is working. I am having the same problem right now. Grounded the gauge it went to full. Ohm meter on send shows that it's working. But still little to no movement on the gauge. Ground strap is there, So my search still continues!

 

[Belle66]

Torkmnstr,
I opened the sending unit and moved the wiper until I got a Full indication on the gauge. The resistance of the sending unit was around 3-5 ohms to produce a Full indication on the gauge. After that I bent the arm for float position. It works well. I now see the needle on the gauge nodding a bit. This has led to a theory as to why this is fairly common.
The theory is that the gauge is damped with an electrolytic capacitor. The original capacitor is old and has a developed significantly more leakage. This will require more voltage to the gauge and produce the nodding as the failing capacitor is going through charge/discharge cycles.
In about a year I plan to pull the instrument cluster again for a variety of reasons and will look for a leaky capacitor at that time.

Joel

 

[Cornpatch MO]

The Mopar sending unit Ohm meter range is 10 - 74 ohms

 

[Torkmnstr]

Yes, my sender was right on when I ran it with my meter

 

[moparedtn]

Ah, there's yet another thing I didn't think of - "Tired Capacitor Syndrome".
When I had my cluster out to fix all the dang lights and gauges and such (not much of anything worked, but now it all does), I replaced the gauge voltage limiter with the available solid state/electronic one. Instructions said the capacitor that accompanied the original limiter (to lessen interference in the radio, supposedly) was no longer needed.
Perhaps it still was after all?
Eh, my gas gauge works; it just shows about 7/8 when the tank is full to spitting gas back out the filler at me. I'll count my blessings and move on.

 

[Cornpatch MO]

My 64 Dodge project. guage does not work. Cleaned and coated the fuel tank and the sender cleaned but not checked . I made a ground strap for the fuel sender. Grounded the wire from the sender to the guage and no responce. I haven't got an ohm meter yet, but assumeing that the sender is ok. Then what is the next steps to check out. How do I make sure the wire from the sender to the guage is ok? Can it be checked out where it plugs into the printed circuit? It has been suggested that maybe my printed circuit is bad. I have installed a new electronic voltage limiter. Any help appreciated....................................MO

This gas gauge is kicking my a**! Exchanged the printed circuit, cleaned up the plug and pins where the wireing connects to the c. board. Put the instrument cluster back in the dash of my 64 Dodge and the gas gauge worked. A couple days later and it does not work... Now this is the part that leaves me clueless--to get any kind of responce from the gas gauge needle, my ign. switch has to be on or engine started---AND-- the headlights has to be on, hi or low beam. !! That leaves me with no idea what it could be. Can anyone help me on this?? Thanks.....................MO.

 

[Cornpatch MO]

This gas gauge is kicking my a**! Exchanged the printed circuit, cleaned up the plug and pins where the wireing connects to the c. board. Put the instrument cluster back in the dash of my 64 Dodge and the gas gauge worked. A couple days later and it does not work... Now this is the part that leaves me clueless--to get any kind of responce from the gas gauge needle, my ign. switch has to be on or engine started---AND-- the headlights has to be on, hi or low beam. !! That leaves me with no idea what it could be. Can anyone help me on this?? Thanks.....................MO.

OK, I think I have a clue. I find that the gas gauge will move the needle if I have just the park lights on. That means the Instrument light s have to be on. So, the gas gauge is getting its power thru the dash lights. I would guess a 12 volt " feed-back". I have changed the printed circuit on the back of the speedo , so it has been messed with.
Question: where is the gas gauge supposed to get it's power? Could it be from one of the studs on the ammeter? There are no wires hooked up to it as I am using a volt meter. My wiring diagram doesn't show the gauges, just to where the dash wires go to the printed circuit plug. Got any more info for me? Thanks..............................MO

 

[miller]

Power supply wire (hot) from the sending unit, goes from it, to one of the pins located on the printed circuit board on the instrument panel. That's how the fuel gauge works, along with the correct grounds.
On your diagram, simply locate that wire off the sending unit...trace it to the panel, to find the correct pin. Sounds like a good check of the circuit board...and grounds!

 

[Cornpatch MO]

Power supply wire (hot) from the sending unit, goes from it, to one of the pins located on the printed circuit board on the instrument panel. That's how the fuel gauge works, along with the correct grounds.
On your diagram, simply locate that wire off the sending unit...trace it to the panel, to find the correct pin. Sounds like a good check of the circuit board...and grounds!

Yes, I have done that. Found the correct pin (light blue wire) and that pin goes into the printed circuit which has a coating over it which prevents seeing where it goes. At first I thought I could just run a 12 volt power source direct to the gauge stud, but that wont work cause it has to run thru the voltage limiter and reduce to about 5-7 volts. I do have the electronic voltage limiter. Further complicating the circuit. Looks like I will have to take the instrument panel out again (bleh) and try to trace the circuit. I don't need any of the other dash gauges to work as I have mechanical gauges. Trying to think of a short-cut. Any other ideas? .......................................MO

 

[miller]

I don't need any of the other dash gauges to work as I have mechanical gauges. Trying to think of a short-cut. Any other ideas?

Suppose you could replace the fuel gauge...since, it sounds like you've changed the others.
But, past that...looking at the circuit board, should be fairly easy to pick out the connection from the correct pin, to the fuel gauge location. Yup...once you pull the panel. Then, simply check that lead with ohm meter. It's either in one piece, or not. Some, after finding a broken lead in those boards, have even soldered a wire in place for a fix. Be SURE to dis-connect the battery first, before pulling the panel.
Just a matter of finding any corrosion, loose connections, and so on. The A to B stuff.

 

[Cornpatch MO]

Suppose you could replace the fuel gauge...since, it sounds like you've changed the others.
But, past that...looking at the circuit board, should be fairly easy to pick out the connection from the correct pin, to the fuel gauge location. Yup...once you pull the panel. Then, simply check that lead with ohm meter. It's either in one piece, or not. Some, after finding a broken lead in those boards, have even soldered a wire in place for a fix. Be SURE to dis-connect the battery first, before pulling the panel.
Just a matter of finding any corrosion, loose connections, and so on. The A to B stuff.

Thanks all for your replys..very helpful.......
I did check into a add on fuel gauge from Speedway, Summit, and Jegs. They are available for Ford and Chevy , but not so much on Mopar. That is because Mopar uses a 10-70 Ohm sender I would assume. Seems like somewhere I saw a gauge that had adjustable Ohm range..maybe just wishful thinking. .........................MO