Fuel sending units

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crewchief

crewchief

A & P Mechanic
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Does anyone know if the the part number 2421493 is interchangeable with the 3621615? The 73 Duster calls for the 3621615 and I have a 2421493 that I want to use. Any input would be very helpful. Pic is of the 242 one.

2421493.jpg
 
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I know this is probably long settled but what I am finding is that 2421493 is superseded by 3621615 which is superseded by 4051004. So technically you could use the 242 in place of the 362. THAT being said...if you haven't used your 242 and it is NOS would you like to sell it? I am restoring my Dads 67 Dart and want to keep it as original as I can.
 
Sorry Dana67, I did install the 2621493. Remember, the Mopars are non-linear systems. Aftermarket ones are ALL linear and will NOT read at the gage.
There are companies out there that can rebuild your old factory one.
 
Why use a plastic float when OEM brass is still available?
 
Daves69 said:
Please clarify, "will not read at the gauge".
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A Mopar gauge is meant to receive a signal in a non-linear resistance format. Therefore you must use a matching signal in order for the gauge to read it properly. Attached are the physical differences between the two types.
All Mopar fuel sending units house the resistor up at the mount at the tank end. aftermarket ones are mounted half way down the tube. I hope this clears this up.
You can use an aftermarket sending unit but you have to change the way the stock gauge receives the signal.
First pic is a linear resistor the second is non-linear

Linear Board.jpg


Non-Linear Board.jpg
 
Oh well had to ask. At least I have a photo of a stock 2421493 to help with my search. The original was replaced long ago, I get the linear vs no linear issue. the current sender I have reads full when the tank is full (18 gallons), 3/4 with 16 gallons, 1/2 with 14 gallons, 1/4 with 12 gallons and a little less than 1/4 at 9 gallons and stayed there for the next 100 miles till I ran out of gas. should have had 3-4 gallons still in the tank by my calculations. (I have checked with a dedicated 5V power supply and 0 to 100 ohm variable resister that the gauge and wiring from the sending unit are good ~75 Ohms empty on the gauge, ~23 1/2 on the gauge, and ~9 full on the gauge) Forgot to add that the grounding strap on the sender to fuel line is in place and good. I will point out that the windings in the top photo look to have a different pitch on the left side than the right side and that would give you a form of non linear sender. also the shape of the tank will effect the linearness of the readings as the tank will deplete from the top down and the A body ( dart) has a basically rectangular tank till the lower 1/4 to 1/3 then it adds the area under the spare tire which will deplete slower than the upper part from a level stand point. Just my 2 cents. I did find the last ( what I was told by the dodge dealer) 4051004 NOS sender in the dodge factory parts system, hope it works properly, will know next week. In the mean time I will be keeping my eyes out for a NOS 2421493 or maybe a wrecking yard OEM that can be repaired by one of the links you all provided.
 
Dana67Dart said:
Oh well had to ask. At least I have a photo of a stock 2421493 to help with my search. The original was replaced long ago, I get the linear vs no linear issue. the current sender I have reads full when the tank is full (18 gallons), 3/4 with 16 gallons, 1/2 with 14 gallons, 1/4 with 12 gallons and a little less than 1/4 at 9 gallons and stayed there for the next 100 miles till I ran out of gas. should have had 3-4 gallons still in the tank by my calculations. (I have checked with a dedicated 5V power supply and 0 to 100 ohm variable resister that the gauge and wiring from the sending unit are good ~75 Ohms empty on the gauge, ~23 1/2 on the gauge, and ~9 full on the gauge) Forgot to add that the grounding strap on the sender to fuel line is in place and good. I will point out that the windings in the top photo look to have a different pitch on the left side than the right side and that would give you a form of non linear sender. also the shape of the tank will effect the linearness of the readings as the tank will deplete from the top down and the A body ( dart) has a basically rectangular tank till the lower 1/4 to 1/3 then it adds the area under the spare tire which will deplete slower than the upper part from a level stand point. Just my 2 cents. I did find the last ( what I was told by the dodge dealer) 4051004 NOS sender in the dodge factory parts system, hope it works properly, will know next week. In the mean time I will be keeping my eyes out for a NOS 2421493 or maybe a wrecking yard OEM that can be repaired by one of the links you all provided.
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Dana67, I had readings at the sending unit (with a good ground); 73 ohms at empty and 10 ohms at full. The gauge moved very slow so be patient when moving the float in the full range. When i installed the sending with 3 gallons of fuel, the gauge showed just about empty.
 
Ya it is hard to be patient with thermal gauges but you have no choice. I saw another thread where there was a Technical service bulletin for 69 Challenger (I think) that talked about bending the pickup tube with the sender on it ( like the aftermarket types) to a steeper angle to correct fuel reading in that car. turns out some of the OEM senders were inches off the floor of the tank and the angle of the sender was off giving incorrect readings and lower than expected fuel capacity.
 
Yes, I dropped my tank and looked thru the filler tube opening and saw where the pick up tube sock rested on the bottom of my tank. If yours is not resting close to the bottom, you can bend it to fit properly. Be sure and move the float to full up to make sure it stops at the top. If it wants to continue make adjustments and take new readings.
 
The only tech bulletin on sending units I have is for the 73's.

Tech Bulletin.jpg
 
I used an endoscope to look into my fuel tank this evening and found that the dime store replacement pickup is about 3 inches from the bottom of the tank. I have an NOS sender on the way so I will play with the old dime store replacement and try bending the tube to see if the float will be 1/2 gauge when there is 9 gallons in the tank and E or below with no gas in the tank.

The 3 inches explains why I ran out of gas with 3-4 gallons in the tank!
 
Dana67Dart said:
I used an endoscope to look into my fuel tank this evening and found that the dime store replacement pickup is about 3 inches from the bottom of the tank. I have an NOS sender on the way so I will play with the old dime store replacement and try bending the tube to see if the float will be 1/2 gauge when there is 9 gallons in the tank and E or below with no gas in the tank.

The 3 inches explains why I ran out of gas with 3-4 gallons in the tank!
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Common problem with aftermarket senders. Happened to me with a couple of them over the years. The pickup tube location has to be checked with each of those sending units. There's even ones where the pickup tube is bent too far down thus preventing the sending unit from sealing properly.

When you get your OEM sending unit be sure to submerge the float in water for a day or 2 to see if there's any pinhole leaks. If you need a new float you can use the one off your junky sending unit, it will fit.
 
On the one hand, I want to send a OEM sender out for rebuild... but which vendor? At what cost?
On the other hand, Buying the reproduction was too simple. Wrong report and now dead after only 8 years... but still without questions/the simple option.
Proper quality reproductions must be too much to ask of the aftermarket.
 
RedFish said:
On the one hand, I want to send a OEM sender out for rebuild... but which vendor? At what cost?
On the other hand, Buying the reproduction was too simple. Wrong report and now dead after only 8 years... but still without questions/the simple option.
Proper quality reproductions must be too much to ask of the aftermarket.
Click to expand...
I have found after doing much research and contacting manufacturers and suppliers. All aftermarket sending units are linear. Only NOS for Mopars are the only way to go. You would have to look into reviews on rebuilders to make your decision. I was fortunate to have located an old unit by shear luck. I paid a high price but it's worth it since there aren't many out there anymore. Plus, I threw my OEM one away with the tank not knowing of the overhaul option.
 
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