sound like the fuel gauge or wiring issue ?

[SoCal250]

He all I replaced both sending units on my 69 250 the one behind the seat had no float attched to it , the one in the aux tank had broken all to pieces both did not work before also i changed the selector switch and checked for power at the senders , the main tank just rises a little , when flipped to aux it goes to full even when tank is empty the gauge is over a hundred bucks new what do you think ?

[Thipdar]

He all I replaced both sending units on my 69 250 the one behind the seat had no float attched to it , the one in the aux tank had broken all to pieces both did not work before also i changed the selector switch and checked for power at the senders , the main tank just rises a little , when flipped to aux it goes to full even when tank is empty the gauge is over a hundred bucks new what do you think ?

If I had to bet, I'd bet on the wiring being the problem.

I'm looking at the 1970 wiring diagram, but it should be 'close enough' for this.

The power for these circuits should come from the Instrument Cluster Constant Voltage Regulator. That power goes through the gauge, then is controlled on the other side of the gauge by the sender(s).

Each "sender" applies a variable ground to that power, which operates the gauge (as long as the tank selector switch is set correctly, that is). Each sender needs to have a valid ground for it to work correctly - hope you were careful about connecting the ground wires at each sender when you replaced the senders.

Rather than look for voltage at the senders, you'd probably be better off to check the wiring from the senders to the selector switch, to make sure each has continuity. Look for zero (or very low) ohms, instead of volts.

My truck has a 6-pin connector (three wires from which go nowhere and are taped off) on the Tank Selector Switch. Of the three active wires on that connector, I believe (I'd have to check to confirm) that the center wire goes to the gauge and the other two wires go to the senders. Wire to gauge is orange for 1970.

If you find continuity from each sender to the wires feeding the switch, the problem is likely at the Instrument Cluster Connector.

If the gauge goes to full even when the tank is empty, that sounds like a full ground... I'd guess that a wire is shorting somewhere, and bypassing the sender. That will be a problem even if you have otherwise-correct continuity.

To help straighten out some confusing things, consider this:
1) The "Senders" actually receive power (they still control the action of the gauge).
2) The "Tank Selector Switch" should actually be called the "Tank Sender Selector Switch", since it selects which sender is controlling the gauge.
3) The "Tank Selector Switch" is not the same thing as the "Fuel Selector Valve" that's down on the floor.

[1guydude]

http://fordification.com//tech/fuel-sending-units.htm

I used this as a guide and I did replace my volt reg on the instrument panel...
hths
-d

[SoCal250]

Thanks for the reply after the post I realized I need to know and read up before I start moving wires around I. The 69 there was a thicker orange wire just there to nothing female connector I thought it went to this breaker looking thing not the CV on the back of the cluster so what I did was hook it to a switched 12 v on that breaker I think that was the aux tank orange . After disconnected it did not go up to full when empty .
I seen all the schematic posted here and it shows it goes to the gauge although the gauge already has a orange to it I think the CV unit is bad only gauge that works is the temp sender and speedo the senders were toast anyway the cab tank had no float / aux tank I removed and cleaned out sender was in pieces at bottom of tank .

[SoCal250]

Is there a co that sells a new gas selector valve ???? I don't know how but good thing I looked I disconnected the main line and off is main I think aux is off and main is aux I don't know how but someone turned the valve or the valve is sticking I thought in off it was off but it was giving gas from the cab tank I have not seen a direct replacement from Macs or Dennis Carpenter or whoever .

[Thipdar]

Is there a co that sells a new gas selector valve ???? I don't know how but good thing I looked I disconnected the main line and off is main I think aux is off and main is aux I don't know how but someone turned the valve or the valve is sticking I thought in off it was off but it was giving gas from the cab tank I have not seen a direct replacement from Macs or Dennis Carpenter or whoever .

Before you replace the valve, check for operation. "Aux" should be towards the rear of the truck; when the handle is rotated to the "Aux" position, the small pointed end of the handle should be aimed at the "Aux" label. When you rotate the handle from "Aux" halfway to "Main", the pointer on the handle should point to "Off". If it points away from "Off", the handle is probably 180 degrees out. It's simple to fix.

On my first F250, the previous owner had reversed the orientation of the handle (removed the screw, pulled the handle off the valve, rotated it 180 degrees, replaced the handle and screw). He did that because he couldn't remember that it was the point that did the indicating... he'd reach down, feel that the paddle of the handle was facing forward and figure that it meant he was on the main tank (which was exactly wrong).

Once I got tired of having to interpret his special signaling system, I removed the screw, pulled the handle off, set it the way it was supposed to be and replaced the screw.

That doesn't sound exactly like what you've described...

Could the handle on your valve be 90 (or maybe 270) degrees off? If so, it should be an easy fix.

However, if you do want to change out the valve:

Valve Assy. (fuel tank selector) basic Ford part # is 9189.
'69/71 F100/250(4x2), F350 Replaced by D2TZ-9189-A

I can't find any on-line.

Tom's Bronco Parts has an aftermarket part that might work.
"Manual Fuel Selector Valve", part number 6185, $49.95
It's for the right vintage of Broncos.
You might have to re-plumb your fuel system.

Let us know what you do... and how it works out

[basketcase0302]

"SoCal250"]Is there a co that sells a new gas selector valve ???? I don't know how but good thing I looked I disconnected the main line and off is main I think aux is off and main is aux I don't know how but someone turned the valve or the valve is sticking I thought in off it was off but it was giving gas from the cab tank I have not seen a direct replacement from Macs or Dennis Carpenter or whoever .

I have a used one for sale I pulled out of my 71 F-350 DRW'.
Shoot me a PM if your interested.