I've cleaned the contacts at the sending unit on the inside tank but still having the guage working when it feels like it. I there a way to narrow it down to the guage switch under the dash or the contact on the board at the dash guages?
The guage has never read full only 3/4 at best but it used to at least always read. Now it is mostly reading on empty!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

Hole in float ?

Ground connection on SU secure ?

ICVR functioning with correct pulse of power ?

Contacts on Printed circuit clean ( Not corroded ) ?

ICVR ground tab secure ?

 

Make sure your ground wire is hooked up good

 

The ground at the sending unit is good. What is ICVR? How do you chase the lead from the switch from tthe guage to the display circuit?

 

Sounds like the constant voltage regulator, not sure where it is on the 67 and newer trucks, but on my 66 it was on the back side on the dash.

 

The ICVR is attached to the instrument panel on my 68. If all other gages are fine, I would lean to ward a bad connection or sending unit. There is a bullet connector under the dash, this is where the wires that come from the sending unit, dome light connect to the main harness. I would twist these connection to make sure you have a good connection. Connect a volt meter on the sending unit and see if it's constant or jumping around. If you have a 100ohm (3-90) variable resister ( or 50 fixed), connect it where the sending unit is. This can be used to test the sending unit.

To trace the leads , notice the color and trace on the wire. It will come out under the dash on the kick panel, high through a plastic garment. The wire is routed over the door frame. At the tank it is ground to the cab, make sure that screw connection is clean and tight.

 

ICVR is the Instrument cluster voltage regulator.

It is pulsing power of 5 volts not constantpower

 

C6DZ-10804-A (1967/70); D1AZ-10804-A (1971/72) .. ICVR (Constant Voltage Regulator) Bad ICVR, the gauges do the hula, fluctuating back and forth.

C0AZ-9202-B .. Fuel Sender Float ~ The float is made from two pieces of copper soldered together, solder breaks down, gas seeps in, float slowly sinks to the bottom of the tank.

C1TF-9276-A .. In Cab Tank Fuel Sender Gasket

D7TZ-9275-G .. In Cab Tank Fuel Sender (comes with float & gasket)

The float, sender and gasket are still available From Ford

Everything except the fuel sender is available from NAPA.

NAPA can cross these Ford part numbers over to the brand they sell.

 

Thanks guys this will be a lot of help.