The Ford Barn

Ed Pitts · 08-13-2010, 06:40 PM

What does the inside of the top of the sending unit contain? As you can see from the pics, the exterior of my sending unit is in good shape. I did the guage test and the needle rose when I briefly grounded the lead to the tank. So the problem has to be with the tank unit. I read the postings on the repops, so that does not appear to be an option. I was considering drilling out the indents on the top of the unit to get to the internals. Can this be done successfully and what is the recommended procedure?
Thanks, Ed

oldskool · 08-13-2010, 06:53 PM

i just used a wide blade screwdriver under the cap and its pops off,there is a bellows inside and contacts that may need cleaning with a point file

Gary Tosel · 08-13-2010, 08:03 PM

The cover will come off with a screw driver carefully prying the top off.

Photo indicates what is inside.

Ed Pitts · 08-13-2010, 08:17 PM

Thanks guys, that is what I needed to know. Ed

Ed Pitts · 08-13-2010, 08:22 PM

Gary, how does the top wire connection attach to the inside? Any precautions when removing the top? Thanks, Ed

19Fordy · 08-13-2010, 08:53 PM

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Gary Tosel · 08-13-2010, 10:25 PM

There is a brass arm in the unit that makes contact on the bottom of the cover where the screw attaches the wire. That screw is obviously insulated from the cover. It is important to make sure the cover is refitted tight to make good contact. Recommend cleaning both the underside of the contact and the end of the contact itself to insure good electrical connection.

If you need to get at the contact points, the internal part can be removed by carefully bending the tabs and removing. I marked the installation location to insure it goes back the same as original.

Hope this helps.

Ed Pitts · 08-14-2010, 10:27 AM

The top came off with the screwdriver exactly as described above. No corrosion was apparent; everything looked clean. Cleaned the points and contact point with the cover but alas, no cigar. Any further thoughts or suggestions? Thanks, Ed

rotorwrench · 08-14-2010, 11:35 AM

Fords fuel gauge set ups were very reliable but like any thing man made they can fail. They used wire wound resistor as a heating element to heat the bi-metalic strip with a small calibrating resistor added in line to get proper synchronization with the gauge unit. The strip bends as it is heated to a point that it will open the contacts. The successive heating and cooling keep the bi-metalic strip busy closing and opening the circuit and the amount of current necessary to do this operation is transfered back to the bi-metalic strip in the quantity indicator gauge causing it to heat & move the same amount as the srip in the sender. When pressure is applied by the float arm, it takes more current to heat the strip causing a coresponding movement in the gauge unit.

If any of these little wires finally burns through or breaks from fatigue then the system is compromised. You will have to get it rewound or replace it with a good one.

Kerby

Mr 42 · 08-14-2010, 12:35 PM

If you ground the wire at the tank for a short moment, and have a friend loking att the gauge it should move quite rapidly.

If it does that then you have a sender problem.

If not then you need to search closer to the gauge, or teh supply of voltage to the gauge.

Ed Pitts · 08-14-2010, 12:47 PM

Quote:

Originally Posted by rotorwrench

Fords fuel gauge set ups were very reliable but like any thing man made they can fail. They used wire wound resistor as a heating element to heat the bi-metalic strip with a small calibrating resistor added in line to get proper synchronization with the gauge unit. The strip bends as it is heated to a point that it will open the contacts. The successive heating and cooling keep the bi-metalic strip busy closing and opening the circuit and the amount of current necessary to do this operation is transfered back to the bi-metalic strip in the quantity indicator gauge causing it to heat & move the same amount as the srip in the sender. When pressure is applied by the float arm, it takes more current to heat the strip causing a coresponding movement in the gauge unit.

If any of these little wires finally burns through or breaks from fatigue then the system is compromised. You will have to get it rewound or replace it with a good one.

Kerby

Thanks Kerby, I checked the continuity of the top strip and it was ok but could not get to the bottom one. That may be where the problem is located. Ed

08-13-2010, 06:53 PM	#2
oldskool Senior Member Join Date: May 2010 Location: shirley ny Posts: 992	Re: 36 Gas Tank Sending Unit repair i just used a wide blade screwdriver under the cap and its pops off,there is a bellows inside and contacts that may need cleaning with a point file

08-13-2010, 08:17 PM	#4
Ed Pitts Senior Member Join Date: May 2010 Location: Irving, Texas Posts: 598	Re: 36 Gas Tank Sending Unit repair Thanks guys, that is what I needed to know. Ed

08-13-2010, 08:22 PM	#5
Ed Pitts Senior Member Join Date: May 2010 Location: Irving, Texas Posts: 598	Re: 36 Gas Tank Sending Unit repair Gary, how does the top wire connection attach to the inside? Any precautions when removing the top? Thanks, Ed

08-13-2010, 08:53 PM	#6
19Fordy Senior Member Join Date: May 2010 Location: Coral Springs FL Posts: 10,925	Re: 36 Gas Tank Sending Unit repair Sponsored Links (Register now to hide all advertisements) A drum brake brake adjusting tool works better than a screwdriver.

08-13-2010, 10:25 PM	#7
Gary Tosel Senior Member Join Date: May 2010 Location: Minnesota Posts: 1,137	Re: 36 Gas Tank Sending Unit repair There is a brass arm in the unit that makes contact on the bottom of the cover where the screw attaches the wire. That screw is obviously insulated from the cover. It is important to make sure the cover is refitted tight to make good contact. Recommend cleaning both the underside of the contact and the end of the contact itself to insure good electrical connection. If you need to get at the contact points, the internal part can be removed by carefully bending the tabs and removing. I marked the installation location to insure it goes back the same as original. Hope this helps.

08-14-2010, 10:27 AM	#8
Ed Pitts Senior Member Join Date: May 2010 Location: Irving, Texas Posts: 598	Re: 36 Gas Tank Sending Unit repair The top came off with the screwdriver exactly as described above. No corrosion was apparent; everything looked clean. Cleaned the points and contact point with the cover but alas, no cigar. Any further thoughts or suggestions? Thanks, Ed

08-14-2010, 11:35 AM	#9
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,425	Re: 36 Gas Tank Sending Unit repair Fords fuel gauge set ups were very reliable but like any thing man made they can fail. They used wire wound resistor as a heating element to heat the bi-metalic strip with a small calibrating resistor added in line to get proper synchronization with the gauge unit. The strip bends as it is heated to a point that it will open the contacts. The successive heating and cooling keep the bi-metalic strip busy closing and opening the circuit and the amount of current necessary to do this operation is transfered back to the bi-metalic strip in the quantity indicator gauge causing it to heat & move the same amount as the srip in the sender. When pressure is applied by the float arm, it takes more current to heat the strip causing a coresponding movement in the gauge unit. If any of these little wires finally burns through or breaks from fatigue then the system is compromised. You will have to get it rewound or replace it with a good one. Kerby

08-14-2010, 12:35 PM	#10
Mr 42 Senior Member Join Date: May 2010 Location: Sweden Posts: 427	Re: 36 Gas Tank Sending Unit repair If you ground the wire at the tank for a short moment, and have a friend loking att the gauge it should move quite rapidly. If it does that then you have a sender problem. If not then you need to search closer to the gauge, or teh supply of voltage to the gauge.