I have a 48 F1 8BA flathead positive ground 6 volt system. The fuel gauge is not working , I have a new sending unit , I have removed it and hooked it straight to the fuel gauge and it moved to full, So I have the ground wire from the sending unit going to the frame, it is a small gauge wire, so thinking I may get like a 16 gauge wire and try grounding it at different places.
My Battery gauge does not move.
My oil gauge only moves when you increase the rpm s. When at idle it is barely to the right of the first square close to zero.
Temp is the only one that seems to work.
Don t know if the speed armiture work because it is not hooked up , have a cable but have not installed it yet.
Right now would like the fuel gauge working more than the other, but would be great to get all working. I think there is a company that refurbish these old gauges?
Any help appreciated,f1butcher .

 

The stock sending unit uses the The King-Seeley (Ford Stock) principle. These sending units supply a full 6V through the heater wire in the gauge in the form of a square wave with the duration of the "on" being the variable determining the gauge reading. The longer the duration, the more fuel in the tank. It is this full 6v of current which heats the bi-metallic strip in the stock gauge that causes the gauge to read via a small gear train (that may adjustable). Most other makes and after market sending units are simply a variable resistor which sends a constant voltage to the gauge, lessening that voltage as the fuel level goes down. Therefore, the sending units signal doesn't heat the bimetallic strip in the gauge as much. Unfortunately, the calibration of the after-market sending units and the stock gauges don't match up very well due to the differences in the principle of the signal.

Bottom line, if you want stock gauges, you need stock style sending units. I know the one aftermarket sending unit that was "supposed" to work with a stock.gauge did not.

The service manual states to test the fuel, oil, or temp gauges, simply independently put a D cell to them and they should read half way (there is no polarity to worry about). If the gauge test good, the sender is replaced.

 

Bmoran4 laid out a great explanation of the OEM 6 volt gauge system and troubleshooting.
I just wanted to add make sure also your cab sheet metal has a good ground to your engine block and frame. That one is easy to forget but with rubber mounts it doesn't generally ground itself very well so its a good idea to ground the firewall to where your battery ground connects to your engine block. As long as you are adding that, you might want to make sure your frame grounds to that same point too.

 

I’ll start by saying I’m no expert, I can only speak for my experience and what other folks have told me.

The oil pressure in my flatty does exactly what yours does. I installed an aftermarket gauge and it’s the same. At cold start it goes up to maybe 40lbs, then after warm up at idle it’s at about 10lbs, rev it up and it goes to between 30-40. I went to a local early ford V8 club and they told me that this is normal. One guy said to consider minimum to be 10lbs/1,000 rpm. Most good engines will be over that. This guys explanation was that the oil pressure pickup is at the wrong location, at the filter. Connect a gauge to the block and it will be very different.

Now that battery gauge. Mine didn’t move either, I even replaced the gauge with a NOS unit. One evening we got stuck with a dead battery, push started it and just made it the 8 miles home. Turned out the generator wasn’t keeping up with the current needs. I had the generator and regulator checked out by a shop, they adjusted it and gave it the ok. Still, I wasn’t getting enough current.

Finally I swapped in a PowerGen 6v +ground alternator. The gauge registers fairly high, maybe 3/4, after startup then goes to center after it recharges the battery. I’ve purposely drained the battery by leaving lights on and the meter goes even higher. Bottom line, the meter was accurate, the generator simply wasn’t charging.

On the gas, I can’t help there. My original sender works fine.

Good luck, I hope my information is accurate.

 

Thanks for all the input, I did hookup a 6 v dry cell to the fuel gauge and it when to full, did not leave on there for long, not wanting to burn it up. I will try the D cell battery just to see if it goes half way. I purchased my sending unit from Dennis Carpenter , which way be what you say is the problem, if so where can I buy a sending unit that will work the old gauge ?
Also have the the firewall grounded to the block and the block grounded to the frame, but the cab has a few rusted out area toward the lower back, so may ground the sending unit to the frame or engine block.
The generator is charging the battery , just the gauge doesn t say so. Thanks about the oil gauge. f1butcher

 

I wouldn’t be so sure of that unless you’ve measured the current going into the battery. I picked up this gauge which verified that I had little charging current. As I said, once I installed the alternator the stock gauge shows that the battery is being charged.

 

OK thanks for the replys, I have got the oil gauge working , it is holding pressure around 30, all I did was changed the oil and cleaned out the oil filter container and new filter. Now on to the fuel gauge.