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Fuel Sending Unit

jag13catjag13catMember
I have exhausted my search from previous posts - any help appreciated.
My fuel gage either reads completely full or empty (with fuel light on) when I switch the sending unit wires. I'm thinking my sending unit float arm is stuck against the interior of the tank. The two wire terminals at the top of the tank are pointing to 9 o'clock. The float swing arm should be pointed to the rear of the tank. Without removing the sending unit to check the arm, is there a relationship of the arm's position and the two exterior wire leads. Any other comments?
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jtpanterajtpanteraMember
I've pulled several sending units out of Panteras. On later cars, it can be done w/o removing the side window. I generally find that that the reostat in the tank that reads the arm/float movement is compromised after 40+ years. Wilkinson sells replacement sending arm units for a reasonable price. I doubt the issue is the wiring from the sending unit to the gauge. Although, easy enough to check with an ohmmeter.
huskerhuskerMember
My sending arm was stuck up against the back of the tank, indicating 1/4 full all the time. This was at the apex of its arc. No way the the float can be stuck up against the tank when its all the way up. The sending arm has to be toward the rear of the tank. Only way it can be installed. The rear most terminal is the fuel light. With power off read resistance between the forward terminal and ground. Mine read 340 ohms empty, 20 ohms full. It appears the sending unit will have to come out no matter what. I bought an endoscope to look inside the tank which was how I determined my float was hung up. i used an old electric pump to drain the tank. By the way when I refilled the tank I pumped gas in by 1 gallon increments. My fuel gauge is way off. The fuel light comes on with 5 gallons in. 1/4 tank was 10 gallons, 1/2 tank was 15 gallons. I was warned the arm is brittle so I left it the way it was. The units are a bit pricey!
liv1sliv1sMember
quote:
Originally posted by comp2:
Good point. Not likely. If the overall diameter is not too big an adapter would not be hard to make.


I've seen this sending unit installed on a Pantera and always wondered where it was sourced. It's got the correct ohm rating to match the factory and my aftermarket VDO gauge. I've had trouble with installing the factory replacement sending unit. The vendors get it through the same source and none are calibrated so you have to try to bend tha float arm yourself. I gave up after the last one I changed would show empty after the fuel level fell below half tank after several attempts to calibrate it. On my last trip, I just checked my odometer and made a mental note to fill up every 200 miles.
When I bring my car back from Vegas, this will be one of my first projects. Using Centroid's Fuel Level Sender should be the final solution in getting an accurate fuel level reading. Too bad it doesn't have a built in fuel pickup though.
Edit: Found the pic of one mount on a stock pantera gas tank using an adapter.

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dave2811dave2811Member
quote:
Originally posted by LIV1S:
....I gave up after the last one I changed would show empty after the fuel level fell below half tank after several attempts to calibrate it. On my last trip, I just checked my odometer and made a mental note to fill up every 200 miles.
When I bring my car back from Vegas, this will be one of my first projects. Using Centroid's Fuel Level Sender should be the final solution in getting an accurate fuel level reading. Too bad it doesn't have a built in fuel pickup though.


Try this unit. I have just ordered one, so I don't have a review yet. It will translate any input into any output. Gotta love modern microprocessors! Thumbs Up! I'll report back once I get it installed.

http://www.technoversions.com/MeterMatchHome.html
davidnunndavidnunnMember

Mike,

Pantera Performance in Colorado sells a Centroid adapter for the Pantera's fuel tank. Unfortunately, there's no provision for a fuel pick-up, so you need to draw fuel from somewhere else. Accordingly, I replaced the drain plug on the bottom of the tank with a high flow banjo fitting from BAT in Florida. I suppose an adapter could be machined that incorporates a fuel pick-up but I decided to go with the PPC adapter. 

Centroid has had a few Pantera owners and vendors provide them with calibration data. Centroid warned me that the specs they have been provided with differed quite a bit, so they were the most comfortable if I provided my own calibration specs.

The other thing they warned me about was, due to the design of the Pantera's fuel level gauge, it is sensitive to input voltage. It will read differently with the engine "off" and the engine "running". They said the Veglia gauge works fine with +6V, so their advice was to supply power with a +6V voltage regulator. That way, it always reads the same, as long as the car's battery/alternator voltage is higher than +6 volts. The sending unit then needs to be calibrated for +6V, for the gauge to read accurately.

Centroid Adapter

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M mpaschettoMember

Hi David,

My electric fuel pump picks up fuel from the bottom of the tank already, so no worries there.  However, the return line after my regulator utilizes the old pick-up location, so I'd have to find a spot for that...

I like the idea of the capacitive sending unit, no moving parts to wear out.
There are a few other options I'm considering:

https://www.tanksinc.com/index...mode=prod/prd346.htm

https://www.vdo-gauges.com/sen...50mm-240-33-ohm.html

https://shop.classicinstruments.com/sn35t

All three of the above are 'two-wire' solutions, so they're simply some sort of variable resistance to ground.

Mike

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