| bassemir | -- 08-26-2019 @ 10:08 PM |
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I am a new owner to a 1935 Ford Convertible Sedan so I don't know a lot about its history. It has a 6v positive ground set up (no 12 v conversion). I am currently investigating my gas gauge that does not appear to be working. The tank has at least 5 gallons of gas (I have never filled it so I don't know the capacity). The tank does not look like the original because it is so clean. I have had the dash gauge out and was able to see the gauge deflect by applying a 1.5v penlight battery. Two 1.5v batteries gave it a little more deflection so I believe the gauge is okay. With the gauge in the car I get no needle deflection (needle below empty). I have 6.5 volts at the top gauge terminal (when the ignition is on). The lower terminal runs back to the sending unit. I've looked at other posts and read how others have pulled and replaced the sending unit, or replaced the cork, etc but I was hoping to do a little more investigating first. I disconnected the wire on the gauge that runs back to the sending unit. It measures about 7 ohms from that wire terminal to ground. That does not seem like much to me but I don't know what the sender range should be. I momentarily connected the gauge terminal for the sending unit to ground and my gauge pegs past the Full mark. I only did this momentarily to avoid possible damage to the gauge. So I concluded when the tank is full, the sending unit must be close to 0 ohms (or grounded). Using a series of 1 ohm resistors (to simulate the sending unit) I put 14 ohms between the sender terminal and ground. The gauge reads over the full mark. I am puzzled with this. With 14 ohms to ground it reads full but with the sending unit wire (which reads 7 ohms to ground) the gauge is unresponsive. Does anyone know what the ohm range is for the 1935 sending unit? I know I know, I should just pull the sending unit out.... but I thought I would see if anyone had another suggestion. RichB
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| flatheadfan | -- 08-26-2019 @ 10:53 PM |
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Rich- A few things. If you have a '35 you should not have an electric gauge. The '35 has a fluid gauge similar to the temperature gauge in appearance. From what you describe, you probably have a '36 tank which requires an electric fuel gauge sender. This is a common swap. As for the fuel gauge you have, it sounds like it is a repo gauge which has a long history of being junk. Assuming you want to keep 6 volts you will need a '36-'55 Ford tank sender. If you go to a 12 volt system an original '56 tank sender will work. Three pictures. The second is a '36 dash gauge with a fuel gauge. The third is a picture of an original Ford sender needed for the dash gauge. The first is the common junk replacement. Hope this helps Tom This message was edited by flatheadfan on 8-26-19 @ 11:01 PM
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| bassemir | -- 08-27-2019 @ 6:46 AM |
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Thanks Tom for the feedback. I did some more research based on your input and read how these '36 electric gauges worked with a bi-metal stripe that opened and closed to control the current to the meter. The 7 ohms on the sender unit wire I was measuring was probably the resistance of the coil in the sending unit. Unless the sending unit is a repro that uses a resistance set up instead of the bi-metal approach. I have a dual gauge, the oil pressure and fuel gauge together. Since getting an original gauge and sending unit for an hydrostatic set up is not likely, I guess I need to pull the sending unit out of the tank to understand how to get things working. Thanks for the response. RichB
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| 40 Coupe | -- 08-27-2019 @ 9:35 AM |
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Getting a hydrostatic sending unit and gauge for 35 is very doable. You mention your tank appears very clean. It is possible it is a replacement tank. None of the replacement tanks have the fittings necessary to use a hydrostatic system for 35. At this point you may be better off repairing the gauge and sender you already have. If the gas line to the engine comes off the front of the tank, then you have a replacement tank since the 35 hydrostatic sending unit has the fuel line attach it it and is mounted on the top of the tank.
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| bassemir | -- 08-30-2019 @ 1:38 PM |
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Here is a quick update: I pulled the sending unit and it appears it is an original like the picture Tom posted above. However, I am missing the float. I can not tell if it is floating (or sunk) in the tank. I jumpered it to the gauge and it appears to work.... sort of. As I move the float arm, the gauge moves from empty to a little more that half a tank. It did not move all the way to Full. Hey, that is better that nothing. I need to find a float and see if I can securely attach it to the float arm. Any suggestions on where to get a float? Thanks guys. RichB
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| MG | -- 08-30-2019 @ 1:48 PM |
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Amazon has them > https://www.amazon.com/Brass-Ford-Fuel-Sending-Float/dp/B01GFDB428/ref=sr_1_4?keywords=gas+tank+float&qid=1567197995&s=gateway&sr=8-4 and > https://www.amazon.com/gas-tank-float/s?k=gas+tank+float
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| TomO | -- 08-31-2019 @ 7:36 AM |
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If your sending unit looks like the one in the 3rd photo that Tom posted, you can get a float from C & G ford parts in CA. https://cgfordparts.com/ufolder/cgcat.php?searchtype=Search&x=x&year_choice=36&searchtextdesc=fuel+sending+unit+float&searchnumber= If your sending unit does not give the full range of the dash gauge, the contact points could be dirty. Use your ohm meter to check from the center contact to the case, the reading should be close to 0 ohms as you should be just reading the resistance of the heating coil. It should not vary much from empty to full. If it does, pry the cap off and carefully clean the contacts. I have attached a photo of the inside of a KS fuel sending unit. Tom
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