Gas Gauge Sending Unit

[rockfoot]

Couple of questions... First; is there an ohmic value that the gas gauge sending unit for a 55' should display when read out (to ground by an ohmmeter) that is "normal"? A range? Is there any other bench test for the sending unit other than actually hooking it up to the gas gauge? I am getting a reading, sometimes and sometimes not. I do not have an analog meter...these digital meters don't really give you the whole story sometimes....
Second: It was mentioned in a post some time ago about the corks (floats) of these sending units getting deteriorated by the ethenol in todays gasoline.... is there a coating or protection for these sending unit corks? What is the fix? [?]Thanks in advance.

1955 President one owner
Moncks Corner, SC

[whacker]

Here is the fix for the cork float:

http://www.gudim.com/ReplacingCorkFloats.html

[Transtar60]

That looks like the same brass float used on Ford ranger fuel gauge sending units.
Local Ford dealer parts department said, there was no replacement float available. So I had to buy the entire unit.

BTW the brass float was 10years old when it developed a leak and failed where the hole was soldered shut and filled with gas.


3E38
4E2
4E28
5E13
7E7
8E7
8E12
8E28

59 Lark
etc

[rockne10]

I took a plastic float off a used jeep sending unit and adapted it by simply bending the tip of my original unit to keep the float attached and ambient.

[stuvw2mny]

NO NO NO, digital meters don't work worth a darn on the sending units. I would only trust an analog meter because the senders are wire-wound resistors upon which a contact from the arm is supposed to make contact. Do a search on gas gauge senders in the forum. Lots and lots of previous stuff on them, including ohmic values, which I don't have at hand right now. If the unit and dash gauge are good another problem area is grounding between the sender (at the gas tank) through the frame back to the dash gauge. These 40+ year old components and ground connections are now failure prone and really hard to diagnose. Good luck!

[rockfoot]

Yeah... I am acutely aware of the analog/digital meter problem...I dropped my old Simpson 260 the other day and it scattered about three ways from h***!! I have to get me a new analog meter. I guess..The situation is that the gas tank is on the bench and the sending unit is out..I have some time before I am ready to put it back in... I did several searches and didn't find what I was looking for... that is why I posted..

1955 President one owner
Moncks Corner, SC

[hopinfox]

I recently replaced a sending unit cork with a carb float. I went to the local NAPA and chose from several and found one with holes that the float arm made a snug fit (with a little bending). It works but adjusting for accuracy takes a little work.

M.hopinfox/Kennesaw,Ga.
62 Hawk
63 Champ
64 Commander
64 Hawk
jealous wife

[starlightchamp]

If car is still 6 volts, ohmic readings will range from near zero to 100. I f car is 12 volts, readings are from 33 to 220 ohms. The current goes in one lug, through the meter elements, out the other lug to the rheostat (variable resistor) element in the tank which is grounded at one end.
Most trouble comes from poor tank grounding. Run a wire from one of the sender attachment screws to a known chassis ground.
Dick Curtis
Santa Barbara

[gordr]

quote:Originally posted by rockfoot

Yeah... I am acutely aware of the analog/digital meter problem...I dropped my old Simpson 260 the other day and it scattered about three ways from h***!! I have to get me a new analog meter. I guess..The situation is that the gas tank is on the bench and the sending unit is out..I have some time before I am ready to put it back in... I did several searches and didn't find what I was looking for... that is why I posted..

1955 President one owner
Moncks Corner, SC

A moment of silence for your Simpson meter. They were the real thing.

If I remember right, the resistance range of the sending unit should be from about 50-150 ohms. If the max/min values fall FAR outside that range, there is something wrong.

Getting Inside The Sending Unit:
These things have a wire-wound resistance unit, built upon a tapered phenolic strip. The idea is to relate the rate of resistance change more closely to float level instead of float arm angle.

The wiper (which is grounded) is a phosphor-bronze spring leaf, and the actual contact point is simply a little dimple stamped into the end of that leaf. When new, it makes contact with only 1 or 2 adjacent wires on the resistance board. After many years of use, the little dimple wears off, and what's left is a slightly raised ring around a small hole. This now spans several wires on the resistor board, and the effect is to make the gage read erratically, as any tiny movement in the arm translates to a major jump in resistance. It's like taking stairs two steps at a time. I've been able to repair these successfully.

The repair:
1. Open up the sending unit by grinding or filing flush the three "rivets" holding the can to the base. Carefully pry the can free with a pocketknife.
2. Examine the resistance unit. If the wires are broken or all messed up in the travel area of the wiper, you may as well discard it right now. If the resistance unit appears to be intact, go on.
3. Look at the wiper. Chances are you will see a hole in its end, where it has been rubbing the resistance strip. That hole will be surrounded by paper-thin metal. Ream the hole out until you reach the base thickness of the metal, and file off any burrs.
4. Now you have to make a new contact button. If you can find a tiny brass rivet or brad with a round head, that should work fine. What I've used before is simply to take a piece of thin brazing rod or silver solder, melt the end to form a small round bead (file smooth as needed), and then clip off a short piece at the end. Insert your new contact button in the hole in the arm, so it just barely projects, and solder in place with rosin-core solder. Make sure there are no sharp edges on the finished button that can snag the wire on the resistor bar.
5. Now temporarily reassemble the unit, and test it to verify that you get a smooth progression of resistance as the float arm is moved.
6. If it tests out OK, reattach the can to the base. I simply use the MIG welder to put a spot of weld where I ground off the "rivets", which are actually swaged-over raised studs pressed into the base plate. If you don't want to weld, you could drill these out and use tiny screws and nuts to anchor the can, but that's more work.

I've done at least 3 this way, and they all worked fine when put into use.

Gord Richmond, within Weasel range of the Alberta Badlands

[JDP]

I bought my Simpson 260 on ebay, here's a few:

http://search.ebay.com/simpson-260_W0QQ_trksidZm37QQfromZR40QQpqryZsimptsonQ20260QQsatitleZQ22simpsonQ20260Q22

JDP/Maryland
64 R2 GT (Sid)
spent to date $62,839.60
63 Daytona HT/4 speed
63 Lark 2 door

[rockfoot]

Gord... Thanks to you for the kind words about the 260... It will be missed[V]...And for the "fix it" tips, too. I will definately look forward to repairing the sending unit, if need be. I was working on my old truck (91 D250, Cummins[])and had set the meter on the roof for some reason.. I was half in and half out, the truck was idling and the meter slipped off of the roof and hit my shoulder...with cat- like reflexes, I spun around and swatted that thing all the way across the shop... the results were scattered about the deck and it was not pretty[xx(]. So it goes... JDP, Thanks for the e-bay tip. I guarentee you that I paid a lot more than they are selling those on e-bay for.. I will definately get my next 260 off of e-bay. Right now though, I am on a ship here in Baltimore and will have to settle for making plans for after June.

1955 President one owner
Moncks Corner, SC