Fuel Sending Unit

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Dec 1, 2003 | 08:40 PM

lrhill

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From: North Texas

Fuel Sending Unit

I installed an aux tank and it registers 3/4 when full. The company I bought it from insists it needs to be adjusted because it is the correct sending unit for Ford trucks. I've had the unit out several times measuring resistance and making sure it has a free range of motion. It is accurate and proportional from 3/4 to empty and I guess I can use it that way, it's just for the money I paid, I'd like it to read full when full.

My question, does anyone know (either from a manual or from actually measuring the resistance) what the full to empty resistance readings are on the stock sending unit?

2003 PSD, CC, 4x4, short bed.

Thanks for any help.
Larry

Dec 1, 2003 | 09:25 PM

Mike W

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From: Central Kali

Hi and welcome to FTE, we sure have been getting new folks lately.

Is it possible the float hangs up near the top so it only reads 3/4? Is it ok when you test out of the tank?

Dec 1, 2003 | 09:34 PM

Franklin2

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From: Virginia

Yea, I would do what Mike suggested. Take the assembly out one more time, leave it plugged in, and if possible(may need a helper here) move the float up and down with the ignition key on, but the truck not running, and see what you have.

Just had a thought. Your truck might have the eletric fuel pump made with the sending unit together. I would think the pump would only run for a second and then cut off, but it might squirt fuel and make a mess.

Dec 2, 2003 | 06:06 AM

lrhill

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From: North Texas

I've checked the range of motion with it out. It actually registers 3/4 when the float is all the way up (full) and empty when the float is al the way down, so I think it's free is the tank with no obstructions.

I'm thinking Ford changed the resistance value in '03 or the float resistance value (on the new one) is just incorrect. I really need to know the "full" resistance value for the stock float. That would answer the question.

Thanks for the responses.
Larry

Dec 2, 2003 | 11:28 AM

Mike W

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From: Central Kali

I don't have the spec but here is a way to fix it: Put a variable resistor (volume control) across the sender. Use a 200 to 500 ohm pot. This will drop the total resistence so the guage will read higher.

Fill the tank and adjust the pot until the guage reads full.

Dec 2, 2003 | 12:33 PM

lrhill

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Joined: Oct 2003

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From: North Texas

I'm willing to try it, would be pretty easy to do. Although, I'm thinking I need more resistance at "full" and adding resistance in parallel would lower the total resistance, or am I remembering wrong. Something about total resistance being less than the least.

Anyway I still need the "empty" resistance to be what it is now so adding resistance in series would definately effect that.

Someone feel free to correct me.
Larry