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Thread: kishy's 1983 Grand Marquis 2dr
Reply #34, 2020-05-21. I removed the fuel sending unit to install a new float on it, and discovered that the inside of the tank and the sending unit itself were very rusty and needed attention. Good photos for reference.
Thread: Sending Unit, Carb Applications (internet finds)
Whole thread is useful, but Reply #22 shows the two different (yet oddly the same) NOS sending units I purchased and now have.
The scenario:
My 83 Grand Marquis was factory built with a carb 302. This means the car was assembled using the carburetor fuel tank: the rear-facing fuel pump hole seen on FI cars is not present. The fuel gauge sender which fits into the 2" hole on the front of the tank also features a fuel pickup tube. This is a returnless system so there is only one fuel line fitting.
The problem:
Initially, the vehicle had an inoperative fuel gauge, and fuel drainback issues.
Upon removal of the sending unit to install a new float, I discovered the tank and sending unit were thoroughly rusted, due to the car having been parked for a long time with an empty tank.
The sending unit rheostat is operational and installing a new float would have corrected the gauge concern.
However, the fuel line fitting (external to the tank) has rust holes through it, and the steel is very thin in areas.
The rust holes through the fuel line fitting did create an external leak, however because this fuel system is a suction system (pump on engine, not in tank), the leak that was occurring was air coming in, rather than fuel going out. Hence the drainback issue. It also would have leaked fuel out if the fuel level were high enough, but it seems just by chance it never was for long enough to happen.
Further repair/refurbishment was required. I preferred the option of finding a replacement part if possible.
Steps taken so far:
I acquired a 1983 carb Town Car for parts, which had a new condition fuel tank and an original but decent-seeming-condition sending unit that would work for my needs.
I installed the replacement fuel tank which corrected the rusty tank concern.
The 83TC sending unit required repair (fuel line fitting), which I successfully did, and I then installed the part.
After filling the tank, it was discovered that the 83TC sending unit has a fuel leak through a rust hole in the round mounting plate.
I attempted to mitigate this by using JB Weld Steelstik putty to fill and enclose the rust hole, however, fuel leaks around the JB Weld product.
I purchased two NOS sending units that turned out to both be the wrong resistance range (one for Lincoln with digital cluster, one for 90-91 carb box).
Current state:
The car is parked with a low fuel level.
The 83TC sending unit remains installed in the car at present. It will leak if the fuel level is at the sending unit height or above.
The 83GM sending unit is on my workbench. It was thoroughly de-rusted and sandblasted. It has flash-rusted over much of its surface area again but this is easily dealt with.
Options to move forward:
Notes about these options:
1. When I repaired the fuel line fitting on that part, the method I used created a fuel bottleneck from normally 5/16 down to approximately 1/4" due to the repair method I used on the fuel line fitting. This may or may not be an issue. Other than this concern, I like the idea of this option quite a bit. It is also worth considering that removing the JB Weld might destroy more of the thin steel encased within. It is unclear to me if metal joining techniques hotter than simple soldering are practical because the adjacent electrical connector is plastic.
2. It might not make sense to do this. Repairing the fuel line fitting will result in the same concern as above. Maybe some form of electroplating could be done to the rest of the part to improve metal strength concerns and ward off future corrosion.
3. I have spares of the EFI parts so this is definitely an option
A. Modify an OE design part: the 5/16" tubing that forms the structure of the part can be extended down to the bottom of the tank, and the plug soldered into it through the mounting plate can be removed. Attaching an external fuel line fitting to the existing 5/16" tubing will create the same concern as #1 though.
B. Second method, which could also be applied to a reproduction part: use a bulkhead fitting to get the fuel through the mounting plate. Build a pickup tube which attaches to the bulkhead fitting.
4. At this point, I have low confidence in ever finding the correct part, used, in condition good enough to use without the same issues I'm already trying to get past. And NOS is an expensive proposition.
5. The NOS parts I have, specifically the 90-91 carb part, can be altered to meet the need. The fuel return line fitting will need to be sealed off, and the rheostat will need to be swapped with one of the correct resistance range. A complicating factor is that the rheostat mounts "backwards" between this part and the ones the correct rheostat will need to come from, which might create the need for breaking the mounting piece off and spot welding (not within my abilities).
This thread serves to gather input as well as eventually show my progress.
I will work on supplying additional photos but the above-referenced threads have some good ones already.
Thread: kishy's 1983 Grand Marquis 2dr
Reply #34, 2020-05-21. I removed the fuel sending unit to install a new float on it, and discovered that the inside of the tank and the sending unit itself were very rusty and needed attention. Good photos for reference.
Thread: Sending Unit, Carb Applications (internet finds)
Whole thread is useful, but Reply #22 shows the two different (yet oddly the same) NOS sending units I purchased and now have.
The scenario:
My 83 Grand Marquis was factory built with a carb 302. This means the car was assembled using the carburetor fuel tank: the rear-facing fuel pump hole seen on FI cars is not present. The fuel gauge sender which fits into the 2" hole on the front of the tank also features a fuel pickup tube. This is a returnless system so there is only one fuel line fitting.
The problem:
Initially, the vehicle had an inoperative fuel gauge, and fuel drainback issues.
Upon removal of the sending unit to install a new float, I discovered the tank and sending unit were thoroughly rusted, due to the car having been parked for a long time with an empty tank.
The sending unit rheostat is operational and installing a new float would have corrected the gauge concern.
However, the fuel line fitting (external to the tank) has rust holes through it, and the steel is very thin in areas.
The rust holes through the fuel line fitting did create an external leak, however because this fuel system is a suction system (pump on engine, not in tank), the leak that was occurring was air coming in, rather than fuel going out. Hence the drainback issue. It also would have leaked fuel out if the fuel level were high enough, but it seems just by chance it never was for long enough to happen.
Further repair/refurbishment was required. I preferred the option of finding a replacement part if possible.
Steps taken so far:
I acquired a 1983 carb Town Car for parts, which had a new condition fuel tank and an original but decent-seeming-condition sending unit that would work for my needs.
I installed the replacement fuel tank which corrected the rusty tank concern.
The 83TC sending unit required repair (fuel line fitting), which I successfully did, and I then installed the part.
After filling the tank, it was discovered that the 83TC sending unit has a fuel leak through a rust hole in the round mounting plate.
I attempted to mitigate this by using JB Weld Steelstik putty to fill and enclose the rust hole, however, fuel leaks around the JB Weld product.
I purchased two NOS sending units that turned out to both be the wrong resistance range (one for Lincoln with digital cluster, one for 90-91 carb box).
Current state:
The car is parked with a low fuel level.
The 83TC sending unit remains installed in the car at present. It will leak if the fuel level is at the sending unit height or above.
The 83GM sending unit is on my workbench. It was thoroughly de-rusted and sandblasted. It has flash-rusted over much of its surface area again but this is easily dealt with.
Options to move forward:
- Re-repair the leak on the 83TC sending unit and continue using it in the 83GM car.
- Repair the 83GM sending unit. Preferably, this would be done in a way that adds material to the whole part, thickening and stengthening it. The metal thickness is significantly compromised.
- Modify an EFI version of the fuel gauge sender to function for this purpose.
- Locate the correct part, in adequate condition.
- Modify one of the NOS parts already on-hand to be suitable for this application.
Notes about these options:
1. When I repaired the fuel line fitting on that part, the method I used created a fuel bottleneck from normally 5/16 down to approximately 1/4" due to the repair method I used on the fuel line fitting. This may or may not be an issue. Other than this concern, I like the idea of this option quite a bit. It is also worth considering that removing the JB Weld might destroy more of the thin steel encased within. It is unclear to me if metal joining techniques hotter than simple soldering are practical because the adjacent electrical connector is plastic.
2. It might not make sense to do this. Repairing the fuel line fitting will result in the same concern as above. Maybe some form of electroplating could be done to the rest of the part to improve metal strength concerns and ward off future corrosion.
3. I have spares of the EFI parts so this is definitely an option
A. Modify an OE design part: the 5/16" tubing that forms the structure of the part can be extended down to the bottom of the tank, and the plug soldered into it through the mounting plate can be removed. Attaching an external fuel line fitting to the existing 5/16" tubing will create the same concern as #1 though.
B. Second method, which could also be applied to a reproduction part: use a bulkhead fitting to get the fuel through the mounting plate. Build a pickup tube which attaches to the bulkhead fitting.
4. At this point, I have low confidence in ever finding the correct part, used, in condition good enough to use without the same issues I'm already trying to get past. And NOS is an expensive proposition.
5. The NOS parts I have, specifically the 90-91 carb part, can be altered to meet the need. The fuel return line fitting will need to be sealed off, and the rheostat will need to be swapped with one of the correct resistance range. A complicating factor is that the rheostat mounts "backwards" between this part and the ones the correct rheostat will need to come from, which might create the need for breaking the mounting piece off and spot welding (not within my abilities).
This thread serves to gather input as well as eventually show my progress.
I will work on supplying additional photos but the above-referenced threads have some good ones already.
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