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Discussion Starter · #1 ·
My first thread on this was locked by the moderator so here we go again. :nonod:When I installed the new sender and filled the car I noticed that it didn't read full. Well I was below E today and when I fill it it only held 10 gallons and read 1/2 tank but the car was full. I drove straight back home and measured the resistance at 21 ohms. Does someone have the specs for the ohms rating of the sender on a 66 Mercury Cyclone.

LR
 

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Can't help with the ohm spec's but are you 100% sure you got the right fuel gauge sending unit. I have a 69 Fairlane that will run out of gas with 5 gallons still in the tank and the gas gauge showing E.
 

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From my pal Seabronc at broncozone.com

The gauge should read "E" when the resistance reaches 73 ohms, Mid scale at 22 ohms. You can test the gauge by putting a 22 Ohm resistor from Radio shack across the connector and putting the key in the ON or ACC position. Also use a 73 Ohm resistor for the E check. No connection at all will show the same as when the key is off. If that works your wires and gauge are good and the sender is bad.
 

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If you short accross the connectors it should go to full.
 

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Discussion Starter · #5 ·
When full my sender is reading 21 ohms and the gauge shows 1/2 tank. I suspect that this new sender is junk. And of course, Classic Car Auto Parts has not responded to my email. :mad:

LR
 

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Discussion Starter · #6 ·
Okay, here's the follow up. The owner of Classic Car Auto parts tried to refute every piece of technical information that I gave him. His last comments were to send him the sending unit, send him freight so he could ship me another one and if "he" found the unit to be defective he would issue credit. This led me to believe that he wasn't going to do s***. So, I ran the car close to empty and drained the tank, pulled the unit and bench tested it. 10 ohms full and 75 ohms empty which is close so he wouldn't have given me credit and I would've paid for two sending units. The bottom line is that the float was so far out of calibration that the unit wasn't reading close to what it should. So I sized things up, did my best at the physics part of the equation and bent the hell out of the float arm in hopes of correcting the sending unit. I think it will be close enough but we'll see. I had to bend the arm about an inch! I will give give a follow up and "BEWARE OF CLASSIC CAR AUTO PARTS".
 

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Just out of curiosity while you had the unit out of the tank, did you hook it up to your guage and see how that read?
 

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Discussion Starter · #8 ·
No Poppy, I didn't. I used the information your friend shared. I placed a 10ohm resistor on the wire and it read full. I placed a 22 ohm resistor on and it read right at or a fuzz above 1/2. I then put a string of resistors in series to create 74 ohms and it read full. To create 74 ohms I put two 22 ohm and three 10 ohm together in series to make the total f 74 ohms resistance. The resistor packages were $2.06 at radio shack, two 5 packs.

LR

PS I put 3 gallons back in and it reads just a fuzz over empty. I'll fill it up today.
 

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Discussion Starter · #9 ·
Just filled it up with 93 octane ethanol free fuel. I put 8 gallons on top of the approx. 2 gallons that were in the tank and it read just on the left side of 1/2. I filled it completely up and she shows on the right side of the full mark. So, if anyone is replacing one of these perhaps looking at the float positions of both the new and old unit would be a good idea. I'm sure this effin thing was made somewhere offshore without the quality control standards that the USA would consider to be the norm, sigh.

LR
 

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Can't help with the ohm spec's but are you 100% sure you got the right fuel gauge sending unit. I have a 69 Fairlane that will run out of gas with 5 gallons still in the tank and the gas gauge showing E.
how can you run out of fuel, AND still have 5 Gallons in it? sounds more like a shot fuel pump to me...
as i recall, when older fords said they were empty, they were empty.
 

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The brass floats on the older FoMoCo tend to get a hole in them.
Check the float and see if it has fuel in it.
You don't have to replace the complete unit .
If the float is bad use Ford basic part # 9202
 

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Discussion Starter · #12 ·
First thing I checked when I pulled it. On my unit the potentiometer went bad. I hope I spelled that right. It sounded like opening a barn door with rusty hinges when i moved it up and down. Gees, and after only 44 years of use, sigh..:incazzato::smilewinkgrin:
 

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how can you run out of fuel, AND still have 5 Gallons in it? sounds more like a shot fuel pump to me...
as i recall, when older fords said they were empty, they were empty.
I think the pickup is too short. The fuel pump is on the engine in a 69. I have had the car stumble going uphill but was able to turn around and drive back to the nearest gas station. There is a drain on the gas tank and when I tried draining the tank on empty I had to go get a 5 gal gas can to get it all out.
 

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Discussion Starter · #14 ·
Sounds like your pickup tube was engineered by the same knuckleheads that may my float arm. I don't know if it is possible to just take the potentiometer off of a new unit and place it on the old original sender but that is something I will consider in the future.

LR
 

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When you installed the new unit, did you place it in the exact position that you removed the old one? Before you removed it, did you mark the outside of the old one and then mark the new one before installing. If not, that could be the problem. :)-O)
 
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