Testing 54 lincoln fuel sending unit


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By B-rad - 2 Months Ago
Pulled the sending unit outta the tank. Cleaned and painted the tank, and want to see if the sending unit is still good. Tried a few things but couldn't get any movement from the meter.
By Ted - 2 Months Ago
Have you tried grounding the sending unit wire to the vehicle?  If the fuel gauge works in doing this, then double check the ground on the fuel tank itself.  If no response to the fuel gauge when grounding the wire taht goes to the sending unit, then the wire coming to the back of the vehicle and/or the gauge itself is suspect. Other comments always welcome.
By miker - 2 Months Ago
Here’s an old post, it won’t answer your question, but gives you a starting point.

http://forums.y-blocksforever.com/Topic22135-1.aspx

Those are King Seeley gauges, as the post says they don’t work on the straight resistance most others do. That said, I think if I had a unit on the bench and went between the wire lug and ground I’d get some kind of reading on a VOM for resistance. But I’ve never done it so I don’t know.

If you run searches for King Seeley gauges you’ll find more information. Much of it will be other makes, especially Jeeps, but the trouble shooting info will apply. If no one surfaces here with an answer, that’s the next step. Final step is the gauge and sender on the bench with a 6 volt battery.

With that Lincoln Y block you’ll probably want a fuel gauge. LOL
By B-rad - 2 Months Ago
This would be a bench test since the unit is outta the tank and I have no idea what condition the wiring is in and no motor or battery. That said, I've watched some videos about testing other types of sending units but none are like this one. I need to know where to put each probe from the meter and move the float to check the numbers. I've put them in pretty much every place I could think of and didn't get anything other than 0 and 1. The car has been sitting since 65 and the tank was pretty sludgy. The sending unit is pretty clean now and moves freely so I'd like to reuse it.
By FORD DEARBORN - 2 Months Ago
There should be continunity through the sender while on the bench. I don't remember at all what the ohm value should be but perhaps something less than 100 ohms but more than 0? Maybe someone can chime in.  It's not a rheostat unit like the 57 and newer senders most are familiar with. It works on the principal of a bimetallic strip heated by a fine wire wound around the bimetal strip and a set of contact points. As the bimetal strip is heated, it will move enough to open the circuit thus allowing it to cool and reclose the contacts. The float arm simply adjusts the closing force of the movable contact. The gauge is similar in that it also had a bimetallic strip heated by fine wire wound around it and mechanically linked to the pointer.  If you do have continunity through the sender, then you may have to wait until the system in in the vehicle with all wires attached and battery installed, then go from there. There are ways to perform a bench test but you would need a fuel gauge and a 6 volt source or a potentiometer to limit the current in absence of a fuel gauge. However, in that setup, values of the components would have to be known so as not to accidently damage the sender.  It's been many years so hopefully I made some sense here - good luck.
By alanfreeman - 2 Months Ago
B-Rad.....I thought that you had said in a previous post that you intended to go to a 12 volt system for your Lincoln.  Somebody correct me if I am wrong, but I don't think that you are going to be able to use your 6 volt sending unit if you do convert your electrical system to 12 volt. There is a reproduction 12 volt sending unit available for a '56 Ford car but I am not sure if the bolt pattern on the flange will match up with your tank.  The last 12 volt sender that I saw had a bolt pattern on the flange designed to fit only the reproduction gas tanks.  Maybe someone else who has done a 6 volt to 12 volt conversion can give you better advice on getting your stock 6 volt fuel gauge working on 12 volts.  
By B-rad - 2 Months Ago
I was under the impression that I could put a restriction, or whatever it's called, in the wiring to the sending unit like the dash
By miker - 2 Months Ago
55 and earlier was 6 volts. 1956 only, at least on the Fords, was 12 volt gauges. One year only. In 57, the gauges were 6 volt and used a voltage reducer from 12 to 6 for the gauges only. Not the clock, radio, heater etc. So that oem unit should allow your 6 volt gauges to work after the 12 volt conversion.

The other items will either need to be changed, or fitted with a voltage reducer of enough capacity to carry the load. I don’t think that works on the radio, due to the positive/negative ground change. But I know there’s solutions for the radio out there.
By B-rad - 2 Months Ago
Yeah. That solution is here already. The radio was removed before I got the car. Any idea if a reduced will work on a fuel sending unit? If I change the bulbs in the dash, will that solve the 6 to 12 problem? Gauges?
By miker - 2 Months Ago
Typically the voltage reducer goes on the hot wire that feed both the gas and temp gauge. Just how that works on the Lincoln you’ll have to find by tracing out the wiring diagram.
By B-rad - 2 Months Ago
Thanks Miker. I'll be asking a few more questions later on regarding the 6 to 12 conversion.
By alanfreeman - 2 Months Ago
Miker....if your logic is correct then why is the sending unit for the '56 Ford a one year only part described as "12 Volt" (Part # 9275-B) whereas the the sender for '49-'55 is described as "6 Volt" and a different (Part # 9275-A)?  If what you are saying is correct, that B-Rad's 6 Volt sender will work on a 12 volt system, then '49 to '56 should all use the same sender.   
By B-rad - 2 Months Ago
The question I have now is, is there a need for a reducer for the fuel sending unit if there's a reducer for the gauge?
By miker - 2 Months Ago
Alan,

For reasons not clear to me, 56 was the only year Ford ran the gauges on 12 volts. When I did the 12 volt conversion on my bird, I bought the 56 senders and gauges for both fuel and gas. I later read I could have used the 57 voltage drop resistor and kept the originals. My gauges were faded, so I would have replaced them anyway. Since voltage to both gauge systems is supplied to the gauge and the sender provides a variable ground (more complicated than that on the King Seeley really) the sender then only sees the voltage coming thru the gauge.

So adding that 57 part, or any number of others including modern solid state units, should run the Lincoln set up. Assuming both the gauges and senders are working properly. Very light load, so it’s a small unit. Heat dissipation is not a problem. For the heater blower, or maybe an overdrive solenoid it might be a large unit with a heat sink. Don’t know, I’ve never done that.


B-rad. Wire the resistor to the wire feeding the gauges (in my bird the hot wire went to the temp and then to the fuel gauge). Now that whole circle only sees the 6 volts. They are not polarity sensitive.
By B-rad - 2 Months Ago
Thanks again Mike. I owe you a whole lot of beers where you come down this way. It'll be a while before I get to the point of converting but, having the knowledge out there sets me at ease. When you coming outta the rain?
By miker - 2 Months Ago
Haha. As soon as the grandkids looking at colleges down there, and the grandkids going to colleges down there clear out, I’ll be back. Grandpa’s Christmas gift to them. Much cheaper for grandpa if I’m not there. LOL
By B-rad - 2 Months Ago
So what I'm hearing out there is that there's not a way to check a fuel sending unit with a meter???
By FORD DEARBORN - 2 Months Ago
What makes this difficult to answer is your sender is a different design than the rheostat type sender most are familiar with. The safest and most simple way would be to have a known good gauge on the bench to hook up in series with your sender and a 6 volt power source.  Simply move the float arm and see if the gauge follows. Establishing the ball park current through the sender would be another way to make the sender respond but if the current is not right, there is the risk of damaging it. Unless you are familiar with this type of work, I wouldn't advise doing it.  The gauge itself would be very easy to test on the bench with a flashlight battery or if in the vehicle, the electrical system would need to be functional. When the electrical system in the vehicle finally becomes functional, the instrument testing will be a piece of cake. 
By B-rad - 2 Months Ago
OK, thanks for the info. So if I have a 6 volt battery and hopefully the gauge still works, how would I conduct the test? I can set it up in the car and hope the gauge works to test. No idea how to wire it to test.
By FORD DEARBORN - 2 Months Ago
If the battery was installed  in the vehicle then the system would be live. Since your engine is still out of the vehicle, I would be concerned with all the stray wires dangling about and possibly shorting out or grounding out making sparks and smoke. One of the ways to at least test the gauge for movement was mentioned earlier in this thread. That is, with the ignition in accessori, very briefly touch the wire that was attached to the sender to ground. The gauge, if working, will start to move to the full position. I would guess that the gauge probably works as they are very reliable. If ever there is an issue, it's usually the sender. If indeed you do get the battery in the vehicle, then why not, with sendere in hand, ground it , then attach the wire to it and see if the gauge responds by moving the float arm?  
By B-rad - 2 Months Ago
I could put battery in the interior of the car and hook jumpers to the back of the gauge and jumper from other side of gauge to sender , also in the interior, move float and look for gauge movement?
By miker - 2 Months Ago
Yes that would work. But make yourself a jumper up with an inline fuse for the non grounded terminal battery terminal. When I’m doing what your doing (or doing check out on a just rewired car) I start out with about 5 amp fuse, go to a 10 for dash lights, parking etc, and finally a 20 amp for everything else in turn. A lot easier to blow a couple small fuses out in the open than to go looking. Or having a direct short and melting something. Once I know all is ok, I’ll actually hook the battery up and check the starter solenoid and starter.
By B-rad - Last Month
OK. So I brought a 6 volt rv battery into the interior of my Lincoln. I have a 6 foot long set of cables with clips on the ends. I tried to hook them up to the back of the gauges but couldn't reach it. I was wondering if I could just use another gauge that was accessible? I tried the temp gauge but wasn't sure if I was hooking it up right. I didn't take into consideration that it's still pos ground. I grounded the Batt neg to chassis and one of the cables coming from the gauge to Batt pos. The other cable from gauge to sending unit. The temp gauge went from cold to hot, but very slowly. It didn't move again when I moved the float, so I'm wondering if either that gauge won't respond to what I'm hooking up to it or if I am hooked up wrong or the sending unit is bad. I'm just checking the sending unit now because I cleaned put the tank and want it to function correctly when I put it back in.
I also have a question about if this sending unit will still work when I convert to 12 volts neg ground.
By FORD DEARBORN - Last Month
It is  usually very tight behind an instrument panel. Since at this time you are only trying to check the fuel and temp instruments, it may be easier and safer to feed the accessory circuit through the radio feed wire. I don't have a wiring diagram for a 54 Lincoln car but usually the radio feed comes from the accessory termial as does the gauges. If you disconnect the radio feed from the radio and apply your 6 volt negative supply to the radio feed wire and the positive to ground, both gauges should have power so you can then test the two instruments in the usual manner. Also, what ever else is on the accessory circuit will be livened up too.  I would strongly take Miker's advise and install a fues inline with your power source just in case. Good luck and hope this helps. 
By miker - Last Month
I like FD’ s idea of back feeding the radio line. Make sure everything that’s loose is isolated and don’t forget the fuse on hook up. I’d start with the positive side grounded, like original. See if the gauge moves. Seems to me in a prior post you said the gas gauge moves from E to F when grounded. So you’re really just testing the sender and its compatibility with the guage. If it works, reverse the leads. I don’t think the King Seeley’s are polarity sensitive. But you’ll know.

It’s also not really important if the gas gauge is that accurate. What’s important is that it reads empty just before it runs dry. I’ve had numerous vehicles that went long miles on full, and then dropped quick. It tells you to go buy fuel. You know when it’s full because you just put the cap back on at the gas station.

Since you didn’t get any ohm readings thru the sender, don’t be surprised if it doesn’t work. But if no one here knows a rebuilder, I know there’s been a couple come up over on the Ford Barn or the HAMB.
By KULTULZ - Last Month

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By B-rad - Last Month
Miker, I was hooked up to the temp gauge, not fuel gauge. I don't know if the temp gauge will react to the fuel sending units stimuli or if it's different from what causes the temp gauge to react normally. It was way easier to get to the back of the temp gauge.
By miker - Last Month
I get that. But without knowing the spec for both senders I wouldn’t assume they’d run the same gauge. Especially with the King Seeley’s and the feedback mechanism in them. But as FD points out, if you backfeed the harness from the radio wire you should power up the whole “accessories” side. You might also power up the “run” side. So no loose wires to ground under the hood or anywhere else. Now you can check the sender at the wiring in the trunk. Separate ground jumper from sending case to body, and wire from gauge hooked up to sender. You can also briefly ground the wire at the trunk and see if the gauge moves. If it does, and not with the sender, you know the sender is functioning.

Don’t forget the small fuse in the battery feed. Even a little RV battery can short a lot of amps to ground, enough to melt wires or start them on fire.