'65 Fuel Gauge Revisited

[Omni]

Good Day All
With the 'Party Barge" ('65 Newport ) nearing completion, I dumped 5 gallon into the tank. A check of the fuel gauge shows nothing - no movement.
Wiring shows continuity from the dash to the sending unit. A test light, however, shows nothing. I have several (used) dash voltage limiters but none have resolved the issue. Looking at a electronic one from Real Time Engineering, but they do not show a listing for '65. (They go from '64 to'67.) Can't find a good phone number for them to verify. Both numbers I found are disconnected.
My main question concerns the fuel gauge itself. Does it have a internal heater? If I understand this correctly, internal heater gauges need to be disabled in order for a electronic unit to work. The gauge cluster is installed in the car as the limiter can be accessed from the bottom.
If the sending unit went south I should still have power (test light lit) wouldn't I?
All comments welcomed.
Thanks for your time
Omni

 

[Sixpactogo]

Not sure what you mean by "internal heater"
I'm guessing you are referring to the voltage limiter that is built into the fuel gauge. It supplies the needed 5 volts to the fuel and temp gauges since 12 volts is too much for them. If I understand your question, you can disable the voltage limiter in the fuel gauge and wire in the electronic limiter you mentioned. If your temp gauge is still working, your voltage limiter is working. If both don't work, it is probably the limiter that has failed.

 

[Big_John]

Good Day All
With the 'Party Barge" ('65 Newport ) nearing completion, I dumped 5 gallon into the tank. A check of the fuel gauge shows nothing - no movement.
Wiring shows continuity from the dash to the sending unit. A test light, however, shows nothing. I have several (used) dash voltage limiters but none have resolved the issue. Looking at a electronic one from Real Time Engineering, but they do not show a listing for '65. (They go from '64 to'67.) Can't find a good phone number for them to verify. Both numbers I found are disconnected.
My main question concerns the fuel gauge itself. Does it have a internal heater? If I understand this correctly, internal heater gauges need to be disabled in order for a electronic unit to work. The gauge cluster is installed in the car as the limiter can be accessed from the bottom.
If the sending unit went south I should still have power (test light lit) wouldn't I?
All comments welcomed.
Thanks for your time
Omni

The sender is a simple rheostat.

All it does is vary the resistance to ground. In other words, if the tank is half full, the measured resistance should be 23 ohms. Empty should be 74 ohms and full should be 10 ohms.

The fuel gauge measures the resistance. It's that simple.

 

[Big_John]

Good Day All
With the 'Party Barge" ('65 Newport ) nearing completion, I dumped 5 gallon into the tank. A check of the fuel gauge shows nothing - no movement.
Wiring shows continuity from the dash to the sending unit. A test light, however, shows nothing. I have several (used) dash voltage limiters but none have resolved the issue. Looking at a electronic one from Real Time Engineering, but they do not show a listing for '65. (They go from '64 to'67.) Can't find a good phone number for them to verify. Both numbers I found are disconnected.
My main question concerns the fuel gauge itself. Does it have a internal heater? If I understand this correctly, internal heater gauges need to be disabled in order for a electronic unit to work. The gauge cluster is installed in the car as the limiter can be accessed from the bottom.
If the sending unit went south I should still have power (test light lit) wouldn't I?
All comments welcomed.
Thanks for your time
Omni

Sorry, had to help Mrs. Big John with something, so I didn't finish...

The simplest way to explain how the gauge itself works is covered better here than I can explain.

How Fuel Gauges Work

So, yes, there is a bi-metal strip that is heated by a small coil and that shows fuel level.

 

[Big_John]

Here's how I diagnosed and fixed mine. Gas Gauge Fix

Simplest thing is to remove and ground the sender wire and see if the gauge reads full.

 

[Omni]

Thanks to All for the responses.
To clarify a couple of points.
1) Some pertinent history: Tank was removed for cleaning (sending unit removed/reinstalled.) All was well before.
2) Only have 1 gauge (fuel). Temp is a hot/cold light. Both of which work.
3) Grounded sender wire with no change. If I read the FSM correctly, a test light will blink as the voltage limiter points open/close. I hooked up my test light to the sender wire terminal and grounded the other end. I have no light at all which is what leads me to believe that the voltage limiter is FUBAR. I also did this at the harness connector behind the kick panel with the same results.
After reading, the thought occurred that 5 gallon may not be enough to move the float on the sender. So, I'm at a cross roads: Do I add more fuel or remove the sender (original as far as I know) to manually move the float arm? Again, the FSM is pointing me toward the limiter.
No mention was made in the reading of having to disable a bi-metal strip in the gauge itself (internal heater) if one does install a electronic dash voltage limiter.

Thanks for the input
Omni

 

[Big_John]

Thanks to All for the responses.
To clarify a couple of points.
1) Some pertinent history: Tank was removed for cleaning (sending unit removed/reinstalled.) All was well before.
2) Only have 1 gauge (fuel). Temp is a hot/cold light. Both of which work.
3) Grounded sender wire with no change. If I read the FSM correctly, a test light will blink as the voltage limiter points open/close. I hooked up my test light to the sender wire terminal and grounded the other end. I have no light at all which is what leads me to believe that the voltage limiter is FUBAR. I also did this at the harness connector behind the kick panel with the same results.
After reading, the thought occurred that 5 gallon may not be enough to move the float on the sender. So, I'm at a cross roads: Do I add more fuel or remove the sender (original as far as I know) to manually move the float arm? Again, the FSM is pointing me toward the limiter.
No mention was made in the reading of having to disable a bi-metal strip in the gauge itself (internal heater) if one does install a electronic dash voltage limiter.

Thanks for the input
Omni

OK, I kept getting interrupted LOL. Mrs. Big John has started getting seedlings ready for her garden and it's in my best interest to help... On many levels.

Let's take the list on.

1. Possible damage to wiring or sender. Another possibility is you no longer have a good ground because the tank is painted(?)

2. The hot/cold lights have zero to do with the gas gauge. Simply put, if the sender reads cold, it lights the cold light etc. Nothing to do with the voltage limiter.

3. If grounding the sender wire has no result, the problem is in the wiring, gauge or voltage limiter. That doesn't mean the sender isn't screwed up too... Just that part of the circuit isn't working.

The voltage limiter is basically not an item that will last 60 years... It's a coil with a set of points. It will open and close the points very fast and by doing that, limit the current. I wouldn't even bother to test one... It's safe to assume it's worn out. That said, I don't know as a test light is the best way to test it anyway. A really good analog voltmeter would be my first choice, followed by a DMM.

I spotted this today. [FOR SALE] - Solid State Rallye Gauge Instrument Voltage Regulators (IVR)

I've used units like this 12v to 5v Volt Converter DROK DC 8-35V to 5V 3A 15W Voltage Regulator Board P... 682516778958 | eBay with good luck. In fact, buy the right one and you can get a USB socket to charge your phone.

Your gauge won't work without the bi-metallic strip and coil. In fact, that's 99% of the gauge, the rest being the pointer and the little gizmo that moves the pointer, so you can't take it out.

 

[rags]

on my '65 300, i had to pull the instrument cluster and clean the several oxidized connections. the grounding points were especially bad. the ground to the sender itself was bad. last thing to get the fuel gauge to work was to empty the gas out of the sender float and solder the pinhole shut. found four separate problems before the fuel gauge worked.

 

[Omni]

Good Morning All
Thanks to who have responded.
Big_John: You got me thinking (rare occurrence) about the test light. It would make sense that a test light would not work as the voltage is reduced from 12V to around 5-7. As stated, I have several used voltage limiters so I checked each one with both of my meters (a cheap O'Reilly special and a Craftsman.
They all read between 0.3 and 6.something. They readings change as the points open/close (I guess).
Don't know if this is normal, however, the electronic versions have a constant output between 5-6 volt.
I am going to bite the bullet and order a new one (Real Time Engineering). Allegedly this is a 'plug-n-play' swap.

Omni

 

[Big_John]

Big_John: You got me thinking (rare occurrence) about the test light. It would make sense that a test light would not work as the voltage is reduced from 12V to around 5-7. As stated, I have several used voltage limiters so I checked each one with both of my meters (a cheap O'Reilly special and a Craftsman.

You also have the delay of the filament in the bulb and it's a larger current load than the gauge.

They all read between 0.3 and 6.something. They readings change as the points open/close (I guess).
Don't know if this is normal, however, the electronic versions have a constant output between 5-6 volt.

That's correct, the points open and close to give an average. In an electronic version, the same thing happens, only it's much faster and you won't see the pulsing. That's basic electronics.

 

[Omni]

Good Day All
The electronic voltage limiter arrived today from Real Time Engineering.
Plugged it in and the gas gauge now works like a charm. I checked it with a meter before installation and the voltage still jumped around like the point style (?) but it works none the less.
Thanks to all who took the time to respond.
Omni

 

[HWYCRZR]

If you read the fine print, I believe the RTE gauge is built to simulate the points style regulators.
I don’t remember if it is this voltage regulator or the meter match that also replicates the slow gauge “warm up”.

 

[3175375]

If you read the fine print, I believe the RTE gauge is built to simulate the points style regulators.
I don’t remember if it is this voltage regulator or the meter match that also replicates the slow gauge “warm up”.

I have the RTE regulator in Shamu, my 1969 Plymouth Fury III vert and the fuel gauge takes a few seconds to register the correct level.
I don’t know if the Meter Match equipment affects this or not.

 

[Big_John]

I don’t remember if it is this voltage regulator or the meter match that also replicates the slow gauge “warm up”.

I don’t know if the Meter Match equipment affects this or not.

My gas gauge with the Meter Match is slow.

 

[3175375]

My gas gauge with the Meter Match is slow.

Do you also have the RTE or equivalent solid state voltage limiter/regulator?

 

[Big_John]

Do you also have the RTE or equivalent solid state voltage limiter/regulator?

My car had the low fuel relay that has the limiter built into it. When I installed the Meter Match, it had a low fuel warning feature and that eliminated the low fuel relay.

I used something like this. Waterproof DC-DC Converter 12V Step Down to 5V Power Supply Module 3A 15W BLACK | eBay
Cheap and seems to be reliable. I think mine is rated at 5amps and I can use it to charge my phone too.