Fuel gauge intermittent
- Thread starter Boeing
- Start date
grumppyoldman
Well-known member
I am going thru something of the same situation. I have a new tank to put in, using the guage that was in the car when I bought it. It is a re-pro, I checked the resistance reading with a vom at on end it reads 100 at the other 10, so don't know how that will work with original gas gauge. I will check everything out before I install tank and new gas line, if and when this damn storm lets me get back to work. They still may have a mandatory evacuation for us. PS Thank's again for the prayer's, so far something has saved us. Al
Boeing
Member
Well Now I am at a complete loss. I have checked the wiring, ran a wire direct to the gauge, wiggled the wires behind the gauge, confirmed a good ground, tried the single "D" cell battery and had the gauge show full, now I have the original sending unit in the tank, replaced the gauge with no change. The Fuel gauge is still not indicating properly what next it can't bee this complicated...
19Fordy
Well-known member
Boeing, I had a similar problem and did the following. My 40 car has been converted to 12V except for the gauge cluster which still operates on 6V using a Ron Francis CONSTANT VOLTAGE REGULATOR that provides a steady 6V. Been using it for 15 years. However, when converting to 12V, I isolated the BATT (voltage) gauge from the original circuit and used an in-line resistor that reduced the incoming 12V to 6V. I did this:
1. Disconnect battery cables from battery
2. Buy a 6V dry cell battery from Lowe's ($4).
3. Disconnect both wires from fuel gauge and, if possible, remove it from your car. Makes it easier to work on.
4.Remove your fuel tank sending unit from your tank and gently clamp it in your vise so you can pry off the top with a brake adjusting tool or big flat blade screwdriver.
5. With the sending unit clamped in vise so that you can move the float arm, hook up the gauge and sending unit as shown in pictorial sketch. After removing the cover, you can attach the input wire directly to the brass spring arm that rubs against the inside of the top of the cover. No need to replace cover after each adjustment.
6.Then move the float through it's range of motion to see how it reads.
7.Using a small flatblade screwdriver, I turned the little star wheel CW to make the needle read closer to FULL and CCW to make it read less.
You can actually touch the bi-metal winding and feel that it gets hot based on the operating principles of the KS unit. I also checked to make sure that the carbon resistor inside the unit was fully seated with good contact. Also checked the soldered connections of the hairline wire. Also, clean all contact points with 600 emery paper.
After an hour or so of playing with the unit, I got the gauge to read better, replaced cover and tried it again to see if it was still ok. It read a little low so I again removed the cover and turned the star wheel CW an itsey, bitsey amount. Then recovered unit and it worked good.
It was interesting to do this and to actually see how the gauge and the sending unit work together on the principle of the bi-metallic strip - not OHMS.
1. Disconnect battery cables from battery
2. Buy a 6V dry cell battery from Lowe's ($4).
3. Disconnect both wires from fuel gauge and, if possible, remove it from your car. Makes it easier to work on.
4.Remove your fuel tank sending unit from your tank and gently clamp it in your vise so you can pry off the top with a brake adjusting tool or big flat blade screwdriver.
5. With the sending unit clamped in vise so that you can move the float arm, hook up the gauge and sending unit as shown in pictorial sketch. After removing the cover, you can attach the input wire directly to the brass spring arm that rubs against the inside of the top of the cover. No need to replace cover after each adjustment.
6.Then move the float through it's range of motion to see how it reads.
7.Using a small flatblade screwdriver, I turned the little star wheel CW to make the needle read closer to FULL and CCW to make it read less.
You can actually touch the bi-metal winding and feel that it gets hot based on the operating principles of the KS unit. I also checked to make sure that the carbon resistor inside the unit was fully seated with good contact. Also checked the soldered connections of the hairline wire. Also, clean all contact points with 600 emery paper.
After an hour or so of playing with the unit, I got the gauge to read better, replaced cover and tried it again to see if it was still ok. It read a little low so I again removed the cover and turned the star wheel CW an itsey, bitsey amount. Then recovered unit and it worked good.
It was interesting to do this and to actually see how the gauge and the sending unit work together on the principle of the bi-metallic strip - not OHMS.
Attachments
Last edited:
FireEngineMike
Senior Member
Post 23 on JSeery's link shows the tank side of a King-Seeley sending unit. Verify that your original looks like that so that you'll know for sure.
Sounds like you have done everything except take the gauge out. Maybe that is the next step - test the gauge and original sending unit on your workbench.
You can try SouthsideObsolete.com (you have to call to check the inventory) for a NOS gauge (Fred does not have any NOS sending units).
You could have your gauge body converted to a modern resistance unit and eliminate the incompatibility between OEM gauge and repro resistance sending unit. Possibilities: AutoInstruments.com, BobsSpeedometer.com, CgrRestoration.com, rsgaugeworks.com, williamsons.com. These are names I have collected the last few years from FordBarn posts; have not worked with any of them.
I hope something works for you. A friend cleaned up my original sending unit and it drives the gauge from E to 7/8 using jumper wires. I have to order a new float so that one of these days I can drain and drop the tank to ditch the repro unit and have a better idea of fuel level.
The other method for both of us is a Post-it on the dash with "get gas by odometer miles".
Sounds like you have done everything except take the gauge out. Maybe that is the next step - test the gauge and original sending unit on your workbench.
You can try SouthsideObsolete.com (you have to call to check the inventory) for a NOS gauge (Fred does not have any NOS sending units).
You could have your gauge body converted to a modern resistance unit and eliminate the incompatibility between OEM gauge and repro resistance sending unit. Possibilities: AutoInstruments.com, BobsSpeedometer.com, CgrRestoration.com, rsgaugeworks.com, williamsons.com. These are names I have collected the last few years from FordBarn posts; have not worked with any of them.
I hope something works for you. A friend cleaned up my original sending unit and it drives the gauge from E to 7/8 using jumper wires. I have to order a new float so that one of these days I can drain and drop the tank to ditch the repro unit and have a better idea of fuel level.
The other method for both of us is a Post-it on the dash with "get gas by odometer miles".
FireEngineMike
Senior Member
19Fordy posted while I was typing. Be careful reinstalling the cover if you follow his instructions. Do not use a mallet because you will mess up everything that you just did. D'Oh.
Boeing
Member
19 forty, Thank you for getting back to me so soon. As you can see from the previous posts I have been dealing with this for some time and have done everything that others have suggested. I will get a picture of the sending unit and post it here. I am sure it is an original Ron Francis. I have the original gauge out now as I have replaced it so now all I need is the 6V dry cell and to remove the original sending unit.
I will let you know how I make out. Thanks again.
I will let you know how I make out. Thanks again.
19Fordy
Well-known member
Boeing, Are you saying that Ron francis makes fuel tank sending units? That would surprise me. In any case, please post photos of what you are dealing with: the fuel gauge, the OEM fuel tank sending unit, any other fuel tank sending unit that you have been trying and the piece that Ron Francis makes, that you mentioned.. Thanks.
JSeery
Member Emeritus
That doesn't sound right, the "D" cell test should show 1/2 scale, not full. Can you post a photo of your sending unit.
Boeing
Member
19Fordy, My mistake on the original sending unit regarding it being Ron Francis. However, I do think it is an original. I did another test using a "D" cell which gave me a half reading and I was able to get a full reading with two "D" cells. I tried to pry off the cap but t will not move. This is getting some frustrating to say the least nothing seems to make sense. You would think that it is simple one gauge, one sending unit a ground wire and a power source...
I will try to upload a picture:https://www.fordbarn.com/forum/album.php?albumid=4144&pictureid=38861
I will try to upload a picture:https://www.fordbarn.com/forum/album.php?albumid=4144&pictureid=38861
JSeery
Member Emeritus
That could be, but the sending unit still needs the missing resistor to work!