blimpy
New member
Caveat : This info relates to the SW fuel gauge system installed in my particular 1947 Cruisaire.
Other systems can and do work differently. Test your system to find out what you have
in YOUR plane, before launching into the following methods .
I found 3 things wrong with my Stewart Warner Sender... left tank in my case.
The fixes were not difficult and required no special parts.
Pictures posted May 6, 2013 - Pictures SW etc.
Please test your system by electrically before removing or taking apart your sender.
When you short across the two terminals AT THE SENDER !!! with a clip lead your gauge will read FULL if your gauge and the associated wiring to the sender is OK. Master switch ON.. Gauge selector set to appropriate tank or course.
If not - fix your wiring problem before messing with the sender.
________________________________________________________________________
These 3 problems result in gas gauge readings being erratic,
inaccurate or NFG. I assume they are common in vintage Bellanca with the Stewart Warner Fuel Level Senders:
1. mechanically Rough though the range of motion... with a tendency to "hang up" in spots.
2. Erratic resistance readings-- possibly beyond the 0-90 ohm range.
3. No reading at all - always reads empty.
TOOLS
Here is what you need to inspect and service your sender.
1. Ohm Meter and 2 clip leads
2. Drill or drill press with good set of bits, and counter sink.
3. Contact Burnishing Tool - GC Electronics GC9338 ( http://www.tubesandmore.com) ~ $1.
Or alternately use extremely fine emery cloth (wet sand paper) 400 grit or more.
4. Electronic Contact Cleaner: Caig De-Oxit D7, GC or MG Products Contact Cleaner
5. Small needle nose pliers, very small screwdriver with GOOD hardened blade.
6. Strong Pliers with smoothest jaws possible. I used electrician’s pliers.
7. Clean flat work table- with a flat under surface. I used heavy plywood.
Removing the Sender -Master OFF
1. Disconnect the sender. Wrap the "hot wire with insulating tape, or put it in a plastic
bag so it cannot short to ground.
2. Mark the tank rim and sender with "permanent" marker at the ground screw. SAE mounting has an offset screw pattern.
Mark the top of the sender with an arrow pointing Forward toward leading edge of wing.
3. Remove the sender, and seal the tank opening temporarily with a plastic glove stuffed with a rag. You can remove the gasket to use as a size and hole template for making a sealing plate if you need one. I used cardboard and a sheet of plastic, but gasket paper and aluminium is nicer.
For SAFETY in a shared hanger or for long term delays, make the dummy plate.
4. Mark the Bottom of the sender -same spot as the ground screw but underneath- so you can align the top shell with the bottom. This will save a lot of time later.
Assess your sender problems and Make Notes:
5. Shake the Float and listen for gas inside. You should not hear sloshing or rattling.
An empty float is very very light. We will test it further later on. Make a note if you hear sloshing or rattling or its heavy.
6. Move the float arm through its range. It should move smoothly, and not tend to catch or
hang up at any point. Yes, you can feel the windings of the resistance wire... but it should be smooooth. Make a note, of any roughness, or tendency to catch or “hang up”.
7. Measure the resistance from stop to stop. At the low point –Empty Tank- you re get 90 ohms. We can adjust this later if needed. At the top – Full Tank- you should read a fraction of 1 ohm). Make a Note, of the high and low position (Full and Empty) readings.
Note: if the stop is not correctly adjusted when the float is high, the wiper will go past the resistance winding and the reading will jump up to the full resistance (about 140 ohms).
8. To check the travel in the full (float up) position tests it against the bottom of your table.
Place the sender with the rubber gasket installed so the bottom of the gasket it even with the bottom of the table, now raise the float until it contacts the bottom of the table (top of the tank).
The reading MUST not be High. It must be a fraction of 1 ohm. Make a note of the reading.
We will adjust that later also.
Sender Disassembly and Inspection
The sender has two main parts... the top shell with the captive wire wound resistor, and the bottom with all the moving parts. These two halves are riveted together with 3 rivets which we will drill out.
9. IF you have the ability to flush rivet the sender back together... then carefully drill out the rivets from the top preferably with a drill press.
Optionally, drill out the rivets from the bottom. You will end up countersinking the resultant holes so V head machine screws will fit flush under the gasket when we re-assemble the sender.
10. Carefully lift off the top of the sender, taking care not to snag or bend the wiper which is attached to the top of the rotating brass shaft – part of the bottom half of the sender. Set the bottom half aside for now, with the internal gasket.
11. Inspect the wire wound resistor inside the top using your magnifier. There should be no broken, burned or out of place turns. The ohm meter should show continuity with about 140 ohms resistance measured between the insulated terminal and the top shell of the sender.
If any turns are touching each other gently separate them with the blade of the tiny screwdriver.
Don’t try to adjust the turns where they are wound closely together.. the winding is NOT Linear.
Note: If any of the winding is broken (open electrically)... you MUST replace or rewind your resistor. That job is beyond the scope of this little ditty. It is NOT possible to solder to resistance wire. But replacing the resistor is easy if you can find a good one.
Cleaning
Spray your intact resistor with Contact Cleaner and wipe with a paper towel or T-shirt rag. Inspect and repeat if necessary. Paper towels are slightly abrasive and will burnish the winding nicely. Leave no paper strands behind. Never use emery cloth on the resistor !
Measure the resistor between the shell and the insulated terminal. Mine reads 140 ohms.
Set the top section aside.
12. Inspect BOTH Bottom Section Electrical Contacts: The spoon shaped Wiper,
And the 2 Finger shaped brass wipers. They work together to conduct electricity to ground through the aluminium casting. This is where we will fix any erratic tendency, roughness, or hang-ups.
Look at the little springy copper/bronze spoon shaped Wiper with your magnifier.
One small surface has been in contact with the resistor winding. The wiper will be dull, and
have an obvious worn spot. If it had a tendency to be rough or hang up, you will see the cause
in front of you. A rough spot may have snagged and hung up on a winding at some point.
Look at the little finger shaped wipers that rub against the aluminium casting. See the deposits ?
Those interfere with the path to ground for the resistance determined by the wiper’s position on the variable resistor.
A. Spray the wiper and the finger contacts with Berryman’s B12 or Contact Cleaner.
The fingers rotate, so clean their path well. Use the hardended blade of the tiny screw driver to burnish the aluminium bright, but do not score or cut the surface. Just remove
any crud and leave a nice clean smooth surface for the fingers to contact. Gently run the burnishing tool under the finger contacts one at a time, and give them each a couple of strokes, flush with contact cleaner. Dry the aluminium contact path with paper towel.
B. Gently use the contact burnishing tool to remove any roughness or dullness on the face of the Spoon shaped springy wiper. Is the old contact spot still rough or deformed? Work on it again. If not perfect :
C. Reposition the wiper slightly to change the contact patch on the wiper.
Use your fine needle nose pliers to gently bend the springy wiper so new
Contact spot will rub against the resistor windings. After you do this, you will need to
Carefully put the top back on the sender – don’t forget the internal rubber gasket - clip the bottom and top together with one alligator clip- so they are electrically connected- then measure the resistance throughout the range of motion of the float arm. Use the assembly marks put on in the beginning.
Check for mechanical and electrical smoothness. Compare max and minimum resistance readings with your notes. We can fix minor differences later. If something is obviously wrong, Take the sender apart, and try again. Very small adjustment of the wiper angle is all that will be required. Caution: Any metal will fatigue and break if repeatedly bent.
All we want it a very small” twist” to change the contact patch – without altering the
angular relationship between the shaft and the contact point on the resistance winding
very much. Don’t bust it being ham handed... the wiper is delicate.
NOTE: Emery cloth should never be used on the resistor windings! I discourage its use on the spoon wiper at all. In any case 400 grit would be MINIMUM. It should NOT be used on the finger wipers. Flush well. I’d avoid HOT solvents on the resistor and insulators like Berryman’s.
13. Temporarily put the sender top and bottom back together using 3 #10 machine screws and nuts once the sender is working smoothing and reliably on the work bench.
Don’t forget the internal gasket. This affects the calibration, and also prevents leaking,
Because when the tank is full gas can slosh up past the rotating shaft into the resistor area. And would then leak out into the wing between the mating halves of the sender
Setting Float Arm Stops.
Look at the sender with the forward arrow pointing to the right. There are two flat metal
Wings or Tabs that act as Stops for the Float Arm. NEVER BEND THESE TABS !!!
On the right side... the long float arm wire hits the stop at the limit of the Upward travel - Tank Full.
On the left side... the short or tail end of the float arm wire hits the stop at the limit of the Downward travel – Tank Empty.
The Maximum Resistance Is Set By Bending the LEFT (short) FLOAT WIRE.
This is how we make sure the Empty Resistance is 90 ohms. 90 ohms=Empty.
Now if it read 95 ohms... well our empty needle reads a little more empty.. but an reading
Of 85 ohms means empty is above E somewhere. Not good.
14. SET EMPTY = 90 OHMS.
If necessary, slightly bend the short end of the float wire - attached to the gear -
to reliably achieve 90 ohms when gravity takes the float to the bottom of its arc.
15. SET FULL = FRACTION OF 1 OHM.
If necessary, slightly bend the Long Float Arm wire...AT THE STOP ONLY
to reliably achieve a fraction of 1 ohm when the wire hits the stop.
Note: Do NOT grab and bend the float arm anywhere but right where it contacts
the stop. The rest of the float position is independent of, and adjusted
after, this basic setting is made.
16. Re-assemble the float for installation using flush rivets or counter sunk machine screws. These rivets or screws are necessary electrical connections.
Repairing Float Leaks – Slowly and Majestically-
Heavy Floats that sink, floats the slosh inside, or bubble when submerged are leaky.
Leaky floats must be emptied and sealed with solder.
There are 2 techniques for finding leaks: The Safe method and The Sure method.
Try the Safe method first, by submerging your float in a dishpan of hot water. Wipe the surface of the float with your hand to get rid of any clinging little bubbles, and then watch.
IF you see bubbles emerging from your float- lift it out and circle the area with a pencil.
Rotate the float 180 degrees so what was up is now down. Try again, looking for
escaping bubbles. Hot water will cause the air/gas to expand inside the float and escape. Cold water won’t. The trouble with the safe method is it often doesn’t work.
Next, try the Sure Method. Carefully heat the float. You can use a heat gun, light bulb, don't use an open flame like I did !
Let Me Say it again : No Open Flame Testing ! This thing isn't a tiny float from a lawn mower carburetor.
I found out that my float contained a LOT more gasoline than I thought it did!
My fist time around carefully using the kitchen stove test I got a nice little candle flame.
The second time the hole grew, and the float shot burning gas across the kitchen, setting things on fire ! In the end, after drilling a drain hole.. I collected enough gas to fill a pill bottle, or blow my face off. Which ever comes first!
100-140 degrees F is hot enough. This is not so hot you cannot touch the float. Oozing fuel is easy to spot. Again mark the hole with a pencil or marker.
Drill the hole bigger with a very small drill to speed the draining of the trapped gasoline.
Double check for other holes. Drill a vent hole if you need to.
Heat the float gently with gun or lamp until ALL the gasoline has evaporated.
Darwin‘s List NOTE: Please do not blow yourself up ! If these is obviously a large amount of gasoline in your float... use the light bulb or heat gun method and liquid will be forced out, there will be no need for – and we positively don’t want any open flame.
Also... if you were wrong, and there is no hole in your float it would be “unfortunate”
to explode it with excess heat. This will ruin your day, and a perfectly good float !
I hope it goes without saying that this work should not be performed around open gas tanks, solvents, in hangers full of airplanes. Take the work home. Safety goggles are good.
Go Slowly and Majestically when you apply heat to a float, turning it over as you go.
17. When you have marked the hole(s) in your float, make a circles of bright
Brass around the hole by rubbing with a scotch brite kitchen pad or similar
Mild abrasive so you have a clean surface to solder to.
Use an electric soldering iron 35 to 100 watts, and radio solder (rosin core not acid core) to seal the hole. Do NOT use a propane torch or other elephant gun methods
which could unsolder the joints in the float. Again you don’t want to apply a lot of heat to a sealed metal container. Remove any residual flux (rosin) with alcohol.
Submerge the float in hot water for 30 minutes. Turn it over once.
Give it the shake and listen test.
18. Put the tank gasket on the sender again. Temporarily mount the sender in the tank using the position markings. Connect the wires to the sender.
Setting Float Position
The aim of setting the upper and lower float positions is to:
A. Insure the float indicates Full and Empty in a repeatable, reliable, and understandable way.
B. Insure that the float cannot “wear through” by bottoming out or topping out on the tank skin when the tank is Empty or Full.
Note: how we set the float is subjective. I prefer to have a little gas under my float when it hits the Empty stop, rather than have my float wear through (again!) In other words the float will hang down, having hit the stop but not the physical bottom of the tank.
I have chosen to have approx 2 gallons in the tank when the sender hits the stop and the gauge reads Empty. How you do it is up to you. We will measure the exact quantity at the end, when we make a calibration chart to go with the gauge.
The regs say the only time a fuel gauge has to be “accurate” is when the tank is empty I like my error on the wet side. If a wing wiggle won’t give a flicker then sucker really is empty !
How one prevents float rubbing with the tanks are full is another problem, especially since it is nearly impossible to see or manipulate the float to the full up position through the gas filler hole. You can bend the float arm to prevent this when truly FULL but only with some compromise at the Empty end of the scale. Considerable
dicking around can be done to achieve the best results.
I chose to use the table bottom measurement method to simulate the tank top.
In practice I only fill to 19 gallons to prevent siphoning out the tank vent when I fill up. That is about all I can do – or have thought to do thus far- to prevent float rubbing when full. I’ll let you know how it works out.
19. Shine your bright “explosion proof” flashlight into the tank and look sideways at the float. Use your non-metallic gas dipstick or other clean probe to touch and move the float. What we want is to be sure float positively can’t touch the bottom of the tank.
Push down on the float to make sure this is true.
Drain gas if necessary just until float is hanging but not floating.
If float touches the bottom of the tank, remove the sender and bend the float arm UP
At the existing 45 degree bend...Not at the stop tab.
Replace sender and check again. Repeat until the float cant bottom out.
This is where you’ve established how much remaining fuel you have in your
tank when the gauge first hits Empty. ¼ to ½ inch clearance when dry is probably
a practical minimum to account for vibration and movement of the un-damped float.
You can experimentally determine how much gas this really is, and adjust it to suit yourself. Or create a positive stop on the UP side, and live with what you get on the Empty end of the arc. It’s important to KNOW how much gas remains, either way.
Turn Master ON and select correct tank on panel.
Gauge should read Empty. Note Needle Position.
Install all Sender Screws and inspection cover when you are satisfied.
Calibrate your Fuel Gauge.
20. Drain tank dry.
a. Add measured amount of fuel until it just touches the bottom of the sender.
Note the amount. This is your “thank you Jesus I’m an idiot” reserve.
b. Add fuel in 5 gallon (1/4 tank) Increments.
Note gauge reading at each point. Tap meter, if Stewart Warner, they stick !
c. Placard gauge with a chart showing qty at ¼, ½, ¾, and Full.
I have this for both sides.
Aren’t Antiques Grand?
Other systems can and do work differently. Test your system to find out what you have
in YOUR plane, before launching into the following methods .
I found 3 things wrong with my Stewart Warner Sender... left tank in my case.
The fixes were not difficult and required no special parts.
Pictures posted May 6, 2013 - Pictures SW etc.
Please test your system by electrically before removing or taking apart your sender.
When you short across the two terminals AT THE SENDER !!! with a clip lead your gauge will read FULL if your gauge and the associated wiring to the sender is OK. Master switch ON.. Gauge selector set to appropriate tank or course.
If not - fix your wiring problem before messing with the sender.
________________________________________________________________________
These 3 problems result in gas gauge readings being erratic,
inaccurate or NFG. I assume they are common in vintage Bellanca with the Stewart Warner Fuel Level Senders:
1. mechanically Rough though the range of motion... with a tendency to "hang up" in spots.
2. Erratic resistance readings-- possibly beyond the 0-90 ohm range.
3. No reading at all - always reads empty.
TOOLS
Here is what you need to inspect and service your sender.
1. Ohm Meter and 2 clip leads
2. Drill or drill press with good set of bits, and counter sink.
3. Contact Burnishing Tool - GC Electronics GC9338 ( http://www.tubesandmore.com) ~ $1.
Or alternately use extremely fine emery cloth (wet sand paper) 400 grit or more.
4. Electronic Contact Cleaner: Caig De-Oxit D7, GC or MG Products Contact Cleaner
5. Small needle nose pliers, very small screwdriver with GOOD hardened blade.
6. Strong Pliers with smoothest jaws possible. I used electrician’s pliers.
7. Clean flat work table- with a flat under surface. I used heavy plywood.
Removing the Sender -Master OFF
1. Disconnect the sender. Wrap the "hot wire with insulating tape, or put it in a plastic
bag so it cannot short to ground.
2. Mark the tank rim and sender with "permanent" marker at the ground screw. SAE mounting has an offset screw pattern.
Mark the top of the sender with an arrow pointing Forward toward leading edge of wing.
3. Remove the sender, and seal the tank opening temporarily with a plastic glove stuffed with a rag. You can remove the gasket to use as a size and hole template for making a sealing plate if you need one. I used cardboard and a sheet of plastic, but gasket paper and aluminium is nicer.
For SAFETY in a shared hanger or for long term delays, make the dummy plate.
4. Mark the Bottom of the sender -same spot as the ground screw but underneath- so you can align the top shell with the bottom. This will save a lot of time later.
Assess your sender problems and Make Notes:
5. Shake the Float and listen for gas inside. You should not hear sloshing or rattling.
An empty float is very very light. We will test it further later on. Make a note if you hear sloshing or rattling or its heavy.
6. Move the float arm through its range. It should move smoothly, and not tend to catch or
hang up at any point. Yes, you can feel the windings of the resistance wire... but it should be smooooth. Make a note, of any roughness, or tendency to catch or “hang up”.
7. Measure the resistance from stop to stop. At the low point –Empty Tank- you re get 90 ohms. We can adjust this later if needed. At the top – Full Tank- you should read a fraction of 1 ohm). Make a Note, of the high and low position (Full and Empty) readings.
Note: if the stop is not correctly adjusted when the float is high, the wiper will go past the resistance winding and the reading will jump up to the full resistance (about 140 ohms).
8. To check the travel in the full (float up) position tests it against the bottom of your table.
Place the sender with the rubber gasket installed so the bottom of the gasket it even with the bottom of the table, now raise the float until it contacts the bottom of the table (top of the tank).
The reading MUST not be High. It must be a fraction of 1 ohm. Make a note of the reading.
We will adjust that later also.
Sender Disassembly and Inspection
The sender has two main parts... the top shell with the captive wire wound resistor, and the bottom with all the moving parts. These two halves are riveted together with 3 rivets which we will drill out.
9. IF you have the ability to flush rivet the sender back together... then carefully drill out the rivets from the top preferably with a drill press.
Optionally, drill out the rivets from the bottom. You will end up countersinking the resultant holes so V head machine screws will fit flush under the gasket when we re-assemble the sender.
10. Carefully lift off the top of the sender, taking care not to snag or bend the wiper which is attached to the top of the rotating brass shaft – part of the bottom half of the sender. Set the bottom half aside for now, with the internal gasket.
11. Inspect the wire wound resistor inside the top using your magnifier. There should be no broken, burned or out of place turns. The ohm meter should show continuity with about 140 ohms resistance measured between the insulated terminal and the top shell of the sender.
If any turns are touching each other gently separate them with the blade of the tiny screwdriver.
Don’t try to adjust the turns where they are wound closely together.. the winding is NOT Linear.
Note: If any of the winding is broken (open electrically)... you MUST replace or rewind your resistor. That job is beyond the scope of this little ditty. It is NOT possible to solder to resistance wire. But replacing the resistor is easy if you can find a good one.
Cleaning
Spray your intact resistor with Contact Cleaner and wipe with a paper towel or T-shirt rag. Inspect and repeat if necessary. Paper towels are slightly abrasive and will burnish the winding nicely. Leave no paper strands behind. Never use emery cloth on the resistor !
Measure the resistor between the shell and the insulated terminal. Mine reads 140 ohms.
Set the top section aside.
12. Inspect BOTH Bottom Section Electrical Contacts: The spoon shaped Wiper,
And the 2 Finger shaped brass wipers. They work together to conduct electricity to ground through the aluminium casting. This is where we will fix any erratic tendency, roughness, or hang-ups.
Look at the little springy copper/bronze spoon shaped Wiper with your magnifier.
One small surface has been in contact with the resistor winding. The wiper will be dull, and
have an obvious worn spot. If it had a tendency to be rough or hang up, you will see the cause
in front of you. A rough spot may have snagged and hung up on a winding at some point.
Look at the little finger shaped wipers that rub against the aluminium casting. See the deposits ?
Those interfere with the path to ground for the resistance determined by the wiper’s position on the variable resistor.
A. Spray the wiper and the finger contacts with Berryman’s B12 or Contact Cleaner.
The fingers rotate, so clean their path well. Use the hardended blade of the tiny screw driver to burnish the aluminium bright, but do not score or cut the surface. Just remove
any crud and leave a nice clean smooth surface for the fingers to contact. Gently run the burnishing tool under the finger contacts one at a time, and give them each a couple of strokes, flush with contact cleaner. Dry the aluminium contact path with paper towel.
B. Gently use the contact burnishing tool to remove any roughness or dullness on the face of the Spoon shaped springy wiper. Is the old contact spot still rough or deformed? Work on it again. If not perfect :
C. Reposition the wiper slightly to change the contact patch on the wiper.
Use your fine needle nose pliers to gently bend the springy wiper so new
Contact spot will rub against the resistor windings. After you do this, you will need to
Carefully put the top back on the sender – don’t forget the internal rubber gasket - clip the bottom and top together with one alligator clip- so they are electrically connected- then measure the resistance throughout the range of motion of the float arm. Use the assembly marks put on in the beginning.
Check for mechanical and electrical smoothness. Compare max and minimum resistance readings with your notes. We can fix minor differences later. If something is obviously wrong, Take the sender apart, and try again. Very small adjustment of the wiper angle is all that will be required. Caution: Any metal will fatigue and break if repeatedly bent.
All we want it a very small” twist” to change the contact patch – without altering the
angular relationship between the shaft and the contact point on the resistance winding
very much. Don’t bust it being ham handed... the wiper is delicate.
NOTE: Emery cloth should never be used on the resistor windings! I discourage its use on the spoon wiper at all. In any case 400 grit would be MINIMUM. It should NOT be used on the finger wipers. Flush well. I’d avoid HOT solvents on the resistor and insulators like Berryman’s.
13. Temporarily put the sender top and bottom back together using 3 #10 machine screws and nuts once the sender is working smoothing and reliably on the work bench.
Don’t forget the internal gasket. This affects the calibration, and also prevents leaking,
Because when the tank is full gas can slosh up past the rotating shaft into the resistor area. And would then leak out into the wing between the mating halves of the sender
Setting Float Arm Stops.
Look at the sender with the forward arrow pointing to the right. There are two flat metal
Wings or Tabs that act as Stops for the Float Arm. NEVER BEND THESE TABS !!!
On the right side... the long float arm wire hits the stop at the limit of the Upward travel - Tank Full.
On the left side... the short or tail end of the float arm wire hits the stop at the limit of the Downward travel – Tank Empty.
The Maximum Resistance Is Set By Bending the LEFT (short) FLOAT WIRE.
This is how we make sure the Empty Resistance is 90 ohms. 90 ohms=Empty.
Now if it read 95 ohms... well our empty needle reads a little more empty.. but an reading
Of 85 ohms means empty is above E somewhere. Not good.
14. SET EMPTY = 90 OHMS.
If necessary, slightly bend the short end of the float wire - attached to the gear -
to reliably achieve 90 ohms when gravity takes the float to the bottom of its arc.
15. SET FULL = FRACTION OF 1 OHM.
If necessary, slightly bend the Long Float Arm wire...AT THE STOP ONLY
to reliably achieve a fraction of 1 ohm when the wire hits the stop.
Note: Do NOT grab and bend the float arm anywhere but right where it contacts
the stop. The rest of the float position is independent of, and adjusted
after, this basic setting is made.
16. Re-assemble the float for installation using flush rivets or counter sunk machine screws. These rivets or screws are necessary electrical connections.
Repairing Float Leaks – Slowly and Majestically-
Heavy Floats that sink, floats the slosh inside, or bubble when submerged are leaky.
Leaky floats must be emptied and sealed with solder.
There are 2 techniques for finding leaks: The Safe method and The Sure method.
Try the Safe method first, by submerging your float in a dishpan of hot water. Wipe the surface of the float with your hand to get rid of any clinging little bubbles, and then watch.
IF you see bubbles emerging from your float- lift it out and circle the area with a pencil.
Rotate the float 180 degrees so what was up is now down. Try again, looking for
escaping bubbles. Hot water will cause the air/gas to expand inside the float and escape. Cold water won’t. The trouble with the safe method is it often doesn’t work.
Next, try the Sure Method. Carefully heat the float. You can use a heat gun, light bulb, don't use an open flame like I did !
Let Me Say it again : No Open Flame Testing ! This thing isn't a tiny float from a lawn mower carburetor.
I found out that my float contained a LOT more gasoline than I thought it did!
My fist time around carefully using the kitchen stove test I got a nice little candle flame.
The second time the hole grew, and the float shot burning gas across the kitchen, setting things on fire ! In the end, after drilling a drain hole.. I collected enough gas to fill a pill bottle, or blow my face off. Which ever comes first!
100-140 degrees F is hot enough. This is not so hot you cannot touch the float. Oozing fuel is easy to spot. Again mark the hole with a pencil or marker.
Drill the hole bigger with a very small drill to speed the draining of the trapped gasoline.
Double check for other holes. Drill a vent hole if you need to.
Heat the float gently with gun or lamp until ALL the gasoline has evaporated.
Darwin‘s List NOTE: Please do not blow yourself up ! If these is obviously a large amount of gasoline in your float... use the light bulb or heat gun method and liquid will be forced out, there will be no need for – and we positively don’t want any open flame.
Also... if you were wrong, and there is no hole in your float it would be “unfortunate”
to explode it with excess heat. This will ruin your day, and a perfectly good float !
I hope it goes without saying that this work should not be performed around open gas tanks, solvents, in hangers full of airplanes. Take the work home. Safety goggles are good.
Go Slowly and Majestically when you apply heat to a float, turning it over as you go.
17. When you have marked the hole(s) in your float, make a circles of bright
Brass around the hole by rubbing with a scotch brite kitchen pad or similar
Mild abrasive so you have a clean surface to solder to.
Use an electric soldering iron 35 to 100 watts, and radio solder (rosin core not acid core) to seal the hole. Do NOT use a propane torch or other elephant gun methods
which could unsolder the joints in the float. Again you don’t want to apply a lot of heat to a sealed metal container. Remove any residual flux (rosin) with alcohol.
Submerge the float in hot water for 30 minutes. Turn it over once.
Give it the shake and listen test.
18. Put the tank gasket on the sender again. Temporarily mount the sender in the tank using the position markings. Connect the wires to the sender.
Setting Float Position
The aim of setting the upper and lower float positions is to:
A. Insure the float indicates Full and Empty in a repeatable, reliable, and understandable way.
B. Insure that the float cannot “wear through” by bottoming out or topping out on the tank skin when the tank is Empty or Full.
Note: how we set the float is subjective. I prefer to have a little gas under my float when it hits the Empty stop, rather than have my float wear through (again!) In other words the float will hang down, having hit the stop but not the physical bottom of the tank.
I have chosen to have approx 2 gallons in the tank when the sender hits the stop and the gauge reads Empty. How you do it is up to you. We will measure the exact quantity at the end, when we make a calibration chart to go with the gauge.
The regs say the only time a fuel gauge has to be “accurate” is when the tank is empty I like my error on the wet side. If a wing wiggle won’t give a flicker then sucker really is empty !
How one prevents float rubbing with the tanks are full is another problem, especially since it is nearly impossible to see or manipulate the float to the full up position through the gas filler hole. You can bend the float arm to prevent this when truly FULL but only with some compromise at the Empty end of the scale. Considerable
dicking around can be done to achieve the best results.
I chose to use the table bottom measurement method to simulate the tank top.
In practice I only fill to 19 gallons to prevent siphoning out the tank vent when I fill up. That is about all I can do – or have thought to do thus far- to prevent float rubbing when full. I’ll let you know how it works out.
19. Shine your bright “explosion proof” flashlight into the tank and look sideways at the float. Use your non-metallic gas dipstick or other clean probe to touch and move the float. What we want is to be sure float positively can’t touch the bottom of the tank.
Push down on the float to make sure this is true.
Drain gas if necessary just until float is hanging but not floating.
If float touches the bottom of the tank, remove the sender and bend the float arm UP
At the existing 45 degree bend...Not at the stop tab.
Replace sender and check again. Repeat until the float cant bottom out.
This is where you’ve established how much remaining fuel you have in your
tank when the gauge first hits Empty. ¼ to ½ inch clearance when dry is probably
a practical minimum to account for vibration and movement of the un-damped float.
You can experimentally determine how much gas this really is, and adjust it to suit yourself. Or create a positive stop on the UP side, and live with what you get on the Empty end of the arc. It’s important to KNOW how much gas remains, either way.
Turn Master ON and select correct tank on panel.
Gauge should read Empty. Note Needle Position.
Install all Sender Screws and inspection cover when you are satisfied.
Calibrate your Fuel Gauge.
20. Drain tank dry.
a. Add measured amount of fuel until it just touches the bottom of the sender.
Note the amount. This is your “thank you Jesus I’m an idiot” reserve.
b. Add fuel in 5 gallon (1/4 tank) Increments.
Note gauge reading at each point. Tap meter, if Stewart Warner, they stick !
c. Placard gauge with a chart showing qty at ¼, ½, ¾, and Full.
I have this for both sides.
Aren’t Antiques Grand?