**&%&^ Fuel Gauge

[HotRod66]

with a new Instrument Cluster Voltage Regulator on the back of the Cluster and new fuel sending unit, The Gauge still wants to fry! Some Flipping PO did some re wireing on the wires that go to the Cluster Voltage Regulator. I guess I need a clear photo of the wires that go to the Voltage Regulator to see if mine are right! why would the gauge want to fry?

BTW this is a 1966 F250 4x4



I hate trying to fix POs Fluckups


Thanks!

[slickmainer]

mine is in storage sorry

[banjopicker66]

HR66: Here is how the wiring should go:
12V keyed from the ignition switch to the voltage regulator.
Regulated power feeds from there to the Fuel, Oil (idiot light), Oil Pressure (gauge, if present) and Temp gauges.
The power then flows from the back of each of the gauges to the sending units. Each sending unit varies the resistance to ground - except for the Oil idiot light, which just grounds out.
Is it possible the Fuel gauge is hooked up to the Oil idiot light? As in inadvertently crossed wires? That would be a direct short to ground when the oil pressure switch is off (no pressure).
Hope this helps.

[huckdeuceman]

Well, the omly thing I know about guege voltage regulator is if is not plugged into the ground on your dash insert it will peg the fuel/temp guages all the way to the right!, it has to be grounded on the metal part of the dash, there is a spade connector
that it plugs into behind the dash to a metal spade connection!, hope this helps?
PS, the wires that connect oil, and alt are about the max length to reach those plugs that are used for them, so if you find a wire that has more play in it,? it might be connected to the wrong gauge/ or idiot light?

[ICEMAN6166]

gas gauge is the orange wire

[ICEMAN6166]

Well, the omly thing I know about guege voltage regulator is if is not plugged into the ground on your dash insert it will peg the fuel/temp guages all the way to the right!, it has to be grounded on the metal part of the dash, there is a spade connector
that it plugs into behind the dash to a metal spade connection!, hope this helps?

only on the plastic insert. the round speedo is a metal panel and does not use that wire

[huckdeuceman]

Sorry about my mistake! I shuold have looked at the pic' you posted? I have a sweep speedo so prolly diff from yours!
appoligize for my lack of prospect!....

[HotRod66]

gas gauge is the orange wire

The Orange wire is right on my! go's to the sending unit! Im thinking its somthing to do with the wire going to the Regulator from the gauge! what side of the Regulator is that wire sopost to go to? Thats where the PO did some rewireing! I don't have the stock connectors that hook to the Regulator.

[banjopicker66]

There are 2 type of spade connectors on the voltage regulator. One is solid, one is sort of "splined."
The solid one is your 12V input, and should be marked "IGN".
The other "splined" one is your 5V-6V output that goes to the gauges, and if I remember is marked "CONTROL" or something similar. These markings should be on the regulator.
To be sure, check the output voltage, it should be no more than 6V.
If the gauge still pegs, check the orange wire for a short between the cluster and the sending unit.
Next, check the sending unit for a direct short to ground as well.

[HotRod66]

There are 2 type of spade connectors on the voltage regulator. One is solid, one is sort of "splined."
The solid one is your 12V input, and should be marked "IGN".
The other "splined" one is your 5V-6V output that goes to the gauges, and if I remember is marked "CONTROL" or something similar. These markings should be on the regulator.
To be sure, check the output voltage, it should be no more than 6V.
If the gauge still pegs, check the orange wire for a short between the cluster and the sending unit.
Next, check the sending unit for a direct short to ground as well.

There are 2 type of spade connectors on the voltage regulator. One is solid, one is sort of "splined."
The solid one is your 12V input, and should be marked "IGN".
The other "splined" one is your 5V-6V output that goes to the gauges, and if I remember is marked "CONTROL" or something similar. These markings should be on the regulator.
To be sure, check the output voltage, it should be no more than 6V.
If the gauge still pegs, check the orange wire for a short between the cluster and the sending unit.
Next, check the sending unit for a direct short to ground as well.

I put in a new wire for the gauge to sending unit, So I know its good! I took my light tester to the Regulator just a min ago, My light tester was flashing on the side of the Regulator that has the splined side! the 12v side was good! Did take my ampmeater to it! have 12v on the 12v side BUT on the splined side it would flash to 8v not for even one sec then it would go to 4v or 5v.

[banjopicker66]

I put in a new wire for the gauge to sending unit, So I know its good!

If the gauge is pegging, there is a short in the sending unit or the wire leading to it. Double check it to be sure. There are a lot of sharp edges on the many pieces that make up the cab, and it is very possible that the wire's insulation is scraped off and is grounding it out.
I would suggest you remove the wire from the sending unit and turn the ignition on. If the gauge pegs, the wire is shorted to ground.
Check for resistance in the sending unit, it should be between 8-12 Ohms full and 70-73 Ohms empty. Anything under 5 Ohms means it is bad.
Check this link out for more detailed instructions. The principles apply to our Slicks, by the way.
http://www.fordification.com/tech/fuel- ... -units.htm

I have 12v on the 12v side BUT on the splined side it would flash to 8v not for even one sec then it would go to 4v or 5v.

This is normal behavior, so your constant voltage regulator is good to go.

[banjopicker66]

It just occurred to me that the problem may be in the gauge itself, or more precisely, in its placement in the cluster.
Note in Iceman's picture the paper insulator under the nuts - yes, only paper - that keeps the gauge studs from grounding out. Your gauge may be grounding itself out on through the nuts or possibly a misaligned stud.
Remove both wires from the back of the gauge.
Leave the gauge in place.
Check for continuity between each stud and ground. You should have infinite Ohms to indicate no continuity at all.
Any reading other than infinite indicates an internal short.

[HotRod66]

It just occurred to me that the problem may be in the gauge itself, or more precisely, in its placement in the cluster.
Note in Iceman's picture the paper insulator under the nuts - yes, only paper - that keeps the gauge studs from grounding out. Your gauge may be grounding itself out on through the nuts or possibly a misaligned stud.
Remove both wires from the back of the gauge.
Leave the gauge in place.
Check for continuity between each stud and ground. You should have infinite Ohms to indicate no continuity at all.
Any reading other than infinite indicates an internal short.

LOL Well Before I seen this I went out side and was thinking! I took the gauge out of the cluster sat it on a rag so it can't ground out! Put the wires on turn then Key and it works! I then put the gauge to ground to see what it would do, It wanted to Peg out! So theres my Problem! Now if U was a lil sooner on that it would a saved me a lot of words! LOL I sure do thank u all for the help!