Attention: TDR Forum Junkies 
This may be of interest to those of you who do not have in-tank lift pumps.
Recently, I had trouble with my fuel sending unit. I finally determined that the problem was with the float valve which lies within the strainer at the bottom of the sending unit. Being tired of spending money at the Dodge dealer, and not really wanting to repair what many have called a piece of junk, I set out to completely replace the entire lower portion of the sending unit with something of my own design. Now I've heard (or more accurately, read) that quite a few guys have basically gutted the lower portion of the sending unit, which, as far as I can tell, leaves the sending unit unable to retain any fuel when the truck is running over hilly terrain unless a minimum amount (quarter tank or so) of fuel is in the tank. That idea is too worrisome for me. I figured I'd share what I came up with. Use the ideas you see here if you want. Throw rocks if you want. Add suggestions if you want. Send me a PM if there's something you're wondering about that I've omitted.
I've drawn a fuel sending unit, as modified. The entire lower portion of the fuel sending unit is made from a stainless steel flour/sugar canister that I found (actually the missus found it) in the kitchen gadget aisle at Wal-Mart. It's 5” in diameter and just a shade under 7” tall. It comes with a glass lid that I have no use for now…. .
In the drawing I referred to the following notes:
Note 1) The reason I originally had the sending unit out was that the supply and return line nipples were perforated with rust, later discovering the float valve problem . I made my own fittings and suction/return tubes only to find out that there is such a thing as the Vulcan Draw Straw II which does all that for about $50. Even though I have all of the necessary tools and sufficient know-how to make the fittings, I would never make my own again unless I had a lot of time on my hands and I couldn't spare 10 or 20 dollars (even making your own costs something)
Also, you'll need to place the sealing gasket (sending unit to tank flange) somewhere above the gauge sender for the step where you install the unit into the tank. The extra girth of this setup, while still small enough to fit into the tank without the gasket in final position, requires that the gasket be “along for the ride” until the gauge sender is past the flange.
Note 2) As is shown in the drawing, you'll need to flatten the side of the canister to allow fastening the fuel gauge sender, plus the fact that unless you flatten this area, the modified sending unit will not fit into the tank with the gauge sender in place.
The flattened area will end up being about 3” wide and extend about 2/3 of the distance down the side of the canister. A little patience is needed as you alternately flatten this area and try to keep the rest of the canister as round as possible. A trial fitting into the tank (canister only) is a must for this step. DON'T DROP IT IN THE TANK!!!
You'll need to decide at what height to position the fuel gauge sender. I measured (on the stock setup) from the bottom of the strainer to the lowest fastening screw and subtracted ½' (the distance the modified unit will sit above the bottom of the tank). See Note 4.
Drill through the side of the canister with a 3/16 bit. Use #8 stainless machine screws and self locking nuts. Make two shims of 1/32” viton rubber sheet between the gauge sending unit (template the shape of the shims and location of screw holes from the sender unit base) and the canister to ensure that the gauge unit is electrically isolated from the canister. (The float arm fulcrum, which has electrical continuity with the blue wire terminal will make contact with the metal canister without the rubber)
Unless you managed to get the flattened area perfectly flat do not try to tighten the screws any more than is necessary to get the unit snug. Over tightening the unit may distort it and cause it to malfunction.
Note 3) The drawing should be fairly clear for this area, but the following should be observed:
I have to admit that even though I specified viton rubber in the drawing and in Note 2, I actually used nitrile rubber myself. I suppose nitrile would be okay ( and about 1/5 the price) if you absolutely know you'll never be running bio-fuels; with the way fuel gets reformulated at regular intervals, who knows? Use viton- this is one miserable job and there's no sense cutting corners to save five bucks. Viton rubber sheet is available in pieces as small as 6”x6” online from McMaster-Carr.
Let's get back to the can. It should go without saying that you should thoroughly de-burr all of the drilled holes. The reed valve you're creating won't work worth a nickel unless the bottom of the canister is flat, smooth and free of burrs.
Use a ¼-20 x ¾ hex head bolt and self locking nut with a 1” OD washer (all stainless) to retain the viton rubber disc in the bottom of the canister. Over tightening will cause the rubber to distort, so only tighten the bolt and nut enough so they don't rattle.
I tested the function of the reed valve by sitting the assembled canister in a large coffee can of water. The canister filled (about ½ gallon I figure) in 15 seconds and when I lifted the canister out of the water, seepage from the valve was minimal. Keep in mind that I was using nitrile rather than viton. Viton is not available in as soft a compound as nitrile; the difference may be noticed in the reed valve's ability to flow liquid into the canister and it's ability to stop the outward flow when viton is used. At 1/32”. however, I doubt that the difference is significant.
One other important item here: The in-tank strainer has been eliminated and replaced with an external in-line strainer(WIX P/N 33270)
Note 4) The flange to canister bottom dimension was determined by measuring from the flange (with gasket in place) to the bottom of the tank and subtracting (in my case) ½”.
I fastened the canister to the existing metal “slides” using stainless ¼-20x3/4 bolts/locknuts (4 of). 3/16 stainless rivets would probably work just as well. Keep whatever fasteners you use as high on the canister as possible to minimize leakage.
When I assembled mine, I fastened the gauge wires, using small zip ties, to the metal slides near the top flange to keep them out of the way. I placed a small length of ¼ vacuum hose around the wires where the zip ties go around the wires to prevent chafing. I also used small lengths of the vacuum hose around the terminal ends.
For the suction tube, I used 3/8 OD copper with a tee fitting soldered on the lower end, placed directly at the bottom of the canister (the two open tee nipples are horizontal) and off to one side. The return tube is 5/16 and is ½“to ¾” from the bottom to minimize air entrainment.
Placing the fully assembled unit in the tank is only a tight squeeze when coaxing the float arm fulcrum past the tank flange. I'm not the most patient person and I got it in there; you can too.
#ad
As I said in introducing this thread, any ideas or constructive criticism are welcome.
I'll be dropping the tank again, in the summer, to replace my nitrile boo-boo with the better viton rubber pieces. If I find an unfolding disaster in there, you'll be the first to know.
I'm fairly sure it'll be okay, owing to the relative simplicity of this setup.
I'm also attaching a better quality drawing in PDF, if I can get a kid to help me.
Drawing coming soon
Recently, I had trouble with my fuel sending unit. I finally determined that the problem was with the float valve which lies within the strainer at the bottom of the sending unit. Being tired of spending money at the Dodge dealer, and not really wanting to repair what many have called a piece of junk, I set out to completely replace the entire lower portion of the sending unit with something of my own design. Now I've heard (or more accurately, read) that quite a few guys have basically gutted the lower portion of the sending unit, which, as far as I can tell, leaves the sending unit unable to retain any fuel when the truck is running over hilly terrain unless a minimum amount (quarter tank or so) of fuel is in the tank. That idea is too worrisome for me. I figured I'd share what I came up with. Use the ideas you see here if you want. Throw rocks if you want. Add suggestions if you want. Send me a PM if there's something you're wondering about that I've omitted.
I've drawn a fuel sending unit, as modified. The entire lower portion of the fuel sending unit is made from a stainless steel flour/sugar canister that I found (actually the missus found it) in the kitchen gadget aisle at Wal-Mart. It's 5” in diameter and just a shade under 7” tall. It comes with a glass lid that I have no use for now…. .
In the drawing I referred to the following notes:
Note 1) The reason I originally had the sending unit out was that the supply and return line nipples were perforated with rust, later discovering the float valve problem . I made my own fittings and suction/return tubes only to find out that there is such a thing as the Vulcan Draw Straw II which does all that for about $50. Even though I have all of the necessary tools and sufficient know-how to make the fittings, I would never make my own again unless I had a lot of time on my hands and I couldn't spare 10 or 20 dollars (even making your own costs something)
Also, you'll need to place the sealing gasket (sending unit to tank flange) somewhere above the gauge sender for the step where you install the unit into the tank. The extra girth of this setup, while still small enough to fit into the tank without the gasket in final position, requires that the gasket be “along for the ride” until the gauge sender is past the flange.
Note 2) As is shown in the drawing, you'll need to flatten the side of the canister to allow fastening the fuel gauge sender, plus the fact that unless you flatten this area, the modified sending unit will not fit into the tank with the gauge sender in place.
The flattened area will end up being about 3” wide and extend about 2/3 of the distance down the side of the canister. A little patience is needed as you alternately flatten this area and try to keep the rest of the canister as round as possible. A trial fitting into the tank (canister only) is a must for this step. DON'T DROP IT IN THE TANK!!!
You'll need to decide at what height to position the fuel gauge sender. I measured (on the stock setup) from the bottom of the strainer to the lowest fastening screw and subtracted ½' (the distance the modified unit will sit above the bottom of the tank). See Note 4.
Drill through the side of the canister with a 3/16 bit. Use #8 stainless machine screws and self locking nuts. Make two shims of 1/32” viton rubber sheet between the gauge sending unit (template the shape of the shims and location of screw holes from the sender unit base) and the canister to ensure that the gauge unit is electrically isolated from the canister. (The float arm fulcrum, which has electrical continuity with the blue wire terminal will make contact with the metal canister without the rubber)
Unless you managed to get the flattened area perfectly flat do not try to tighten the screws any more than is necessary to get the unit snug. Over tightening the unit may distort it and cause it to malfunction.
Note 3) The drawing should be fairly clear for this area, but the following should be observed:
I have to admit that even though I specified viton rubber in the drawing and in Note 2, I actually used nitrile rubber myself. I suppose nitrile would be okay ( and about 1/5 the price) if you absolutely know you'll never be running bio-fuels; with the way fuel gets reformulated at regular intervals, who knows? Use viton- this is one miserable job and there's no sense cutting corners to save five bucks. Viton rubber sheet is available in pieces as small as 6”x6” online from McMaster-Carr.
Let's get back to the can. It should go without saying that you should thoroughly de-burr all of the drilled holes. The reed valve you're creating won't work worth a nickel unless the bottom of the canister is flat, smooth and free of burrs.
Use a ¼-20 x ¾ hex head bolt and self locking nut with a 1” OD washer (all stainless) to retain the viton rubber disc in the bottom of the canister. Over tightening will cause the rubber to distort, so only tighten the bolt and nut enough so they don't rattle.
I tested the function of the reed valve by sitting the assembled canister in a large coffee can of water. The canister filled (about ½ gallon I figure) in 15 seconds and when I lifted the canister out of the water, seepage from the valve was minimal. Keep in mind that I was using nitrile rather than viton. Viton is not available in as soft a compound as nitrile; the difference may be noticed in the reed valve's ability to flow liquid into the canister and it's ability to stop the outward flow when viton is used. At 1/32”. however, I doubt that the difference is significant.
One other important item here: The in-tank strainer has been eliminated and replaced with an external in-line strainer(WIX P/N 33270)
Note 4) The flange to canister bottom dimension was determined by measuring from the flange (with gasket in place) to the bottom of the tank and subtracting (in my case) ½”.
I fastened the canister to the existing metal “slides” using stainless ¼-20x3/4 bolts/locknuts (4 of). 3/16 stainless rivets would probably work just as well. Keep whatever fasteners you use as high on the canister as possible to minimize leakage.
When I assembled mine, I fastened the gauge wires, using small zip ties, to the metal slides near the top flange to keep them out of the way. I placed a small length of ¼ vacuum hose around the wires where the zip ties go around the wires to prevent chafing. I also used small lengths of the vacuum hose around the terminal ends.
For the suction tube, I used 3/8 OD copper with a tee fitting soldered on the lower end, placed directly at the bottom of the canister (the two open tee nipples are horizontal) and off to one side. The return tube is 5/16 and is ½“to ¾” from the bottom to minimize air entrainment.
Placing the fully assembled unit in the tank is only a tight squeeze when coaxing the float arm fulcrum past the tank flange. I'm not the most patient person and I got it in there; you can too.
#adAs I said in introducing this thread, any ideas or constructive criticism are welcome.
I'll be dropping the tank again, in the summer, to replace my nitrile boo-boo with the better viton rubber pieces. If I find an unfolding disaster in there, you'll be the first to know.
I'm fairly sure it'll be okay, owing to the relative simplicity of this setup.
I'm also attaching a better quality drawing in PDF, if I can get a kid to help me.
Drawing coming soon
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