Fuel Sending Unit

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Otto Skorzeny
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Re: Fuel Sending Unit

Postby Otto Skorzeny » Mon May 31, 2021 5:54 am

Good job!.

I know you aren't going to take the sending unit out again but do you think that the float arm could be bent further to register even more accurately?

Coincidentally I installed a new fuel tank and sending unit in a '66 Mustang yesterday morning. Unlike Toronados that have parts that can't be obtained, Mustang parts are so common I had over three choices for sending unit and about 6 choices for a new fuel tank (any combination of zinc, Ni-Terne steel, stainless steel, and 16gal or 22gal)

It is quite satisfying to have a working fuel gauge. As you experienced, this car also idles and runs a lot smoother now that it can get all the gas it wants without sucking it through rust and crud.
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NicolasB
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Re: Fuel Sending Unit

Postby NicolasB » Mon May 31, 2021 9:58 am

Nice job (and car)! That old sending unit seems to have a “bit” of rust haha! It’s so nice when a gauge works since you have the peace of mind.

The float can be bent further down for better accuracy, but I didn’t do that since I was afraid that I am going to run out of gas before the gauge reaches “empty”.

NicolasB
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Re: Fuel Sending Unit

Postby NicolasB » Mon May 31, 2021 9:18 pm

So I just drove the car for a bit with a quarter tank, and the gauge needle moved around immediately when the fuel moved in the tank. On an incline and when pressing the gas the gauge reads empty. It only goes higher when I brake. Is that what you are experiencing as well Otto? It stabilizes when I am not moving or am traveling at a steady speed on a straight, flat road.

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Otto Skorzeny
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Re: Fuel Sending Unit

Postby Otto Skorzeny » Tue Jun 01, 2021 4:12 am

No. My Toronado gauge works as it should but the tank and gauge are original.

The Mustang tank is designed differently. There are no baffles but the sender is mounted at the front of the tank with the float extending to the center of the tank. Since the float is centered in the tank, the fuel level remains fairly constant regardless of the angle - sort of like the fulcrum of a teeter totter.

NicolasB
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Re: Fuel Sending Unit

Postby NicolasB » Tue Jun 01, 2021 9:32 am

Ah okay, yeah the new sending unit is very sensitive and moves immediately whenever the fuel sloshes around. Maybe when I fill the gas tank it won't be as bad as when it is only a 1/4 full.

NicolasB
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Re: Fuel Sending Unit

Postby NicolasB » Tue Jun 01, 2021 7:49 pm

Sooo, does anyone know how to replace the rubber fuel lines that go to the tank? Mine is routed inside the frame and seems like a huge pain to replace. Also the return line broke since it’s too dry and old and now I have to take the tank back down.

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Otto Skorzeny
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Re: Fuel Sending Unit

Postby Otto Skorzeny » Wed Jun 02, 2021 12:54 pm

It's a royal pain in the ass. Use a wire or electrician's fish tape to get through the frame and attach the new hose to it and pull it back through. Do the fuel line and the return line at the same time. Wrap them with electrician's tape every foot or so so they go through together.

Absolutely the dumbest fuel line design I've ever seen on any car.

bcroe
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Re: Fuel Sending Unit

Postby bcroe » Wed Jun 02, 2021 2:30 pm

The biggest problem with gauge accuracy is the float arm. The float
motion should be just enough to touch the top and the bottom. Note
on the left stock unit, the float will not even move till the gas level
drops by 1/3. Then it drops like a rock. The arm on the right has
been lengthened and bent to work over the entire range. It will tell
me within 1 gallon, how much gas is needed to fill the tank.

This is done to all my cars, along with proper calibration of the
speedometer. Bruce Roe
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NicolasB
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Re: Fuel Sending Unit

Postby NicolasB » Thu Jun 03, 2021 9:27 am

Update: So I was able to fix the leak I had in the fuel tank by sealing the hole with TankWeld where the original return line port was located (someone broke it in the past and used epoxy to keep it in place, but it broke again and wouldn’t stop leaking gasoline) and using the new return line that the sending unit included. I also cut parts of the old fuel lines that were cracking and damaged and used a nylon connector to join them, as well as the new rubber lines, together. No leaks anymore! I was going to try to replace the whole lines, but the clamps that joined the rubber and the metal lines were too far in the hole where the rubber lines are supposed to be fished out.

In terms of the sending unit, I seem to get a pretty accurate reading when I get to 3/4. Technically, the gas pump is supposed to stop at 6 gallons, but it did at 5.7. However, filling the tank only slightly helped dampen the fuel gauge tendency to bounce around.

NicolasB
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Re: Fuel Sending Unit

Postby NicolasB » Wed Jun 09, 2021 9:42 am

Looking at how fast the fuel gauge drops really shows how much of a gas hog this car is haha, never truly knew how much it could consume a quarter tank on the city until now.


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