[Chrysler300] 300D gas tank question

Hi all:

Years ago I replaced the sender unit on my F. When comparing the new one with the old one, I found that the range of movement and ohmic readings were not the same. The unit was manufactured by a company in MA. I drew a to-scale front to back cross section sketch of the tank at the sender unit, laid the new unit on the sketch, moved the float througn its range on the sketch, and bent the new rod to read the correct ohmic measurements. The result is that my sender unit gives a reasonably accurate reading of the fuel remaining in the tank, but, since most of my driving is long distance and get about 10 mpg at 70 mph, I normally find a gas station and pit stop at about 170 miles. Good distance to stretch legs also and fill the tummy.

Dan Reitz

In a message dated 1/6/2018 5:28:21 PM Pacific Standard Time, Chrysler300-noreply@xxxxxxxxxxxxxxx writes:

John — I think you have a sending unit for later thermal gauges , 60 and later . Not sure from your Post the year of car you are talking about ? He is in a 57 ? 57-59 are 20 to 200 . ( from measuring a 57 original) 57-59 have instant responding magnetic gauges. Thermal are 10-90 ohm senders . Chinese ones are very inaccurate , 10-90 part is fairly close ( 75?) but calibration awful — even when in correct car . Or in my case truck . They are selling one sender for all mopar cars . Clueless .

Bought three from Van’s , two in restored 70 ‘s trucks and a 67 dart — both trucks drop fast to E , but 6 gallons still in tank . Dart lingers near e for last 5 gallons ..ran out twice . Guessing “is it empty? “ Ran out in truck , used to running around on E . PIA . I try to save old one now , often you can . If you bend rod it often goes past full which IS better . The 57 has positive mechanical stops on the old one .

Could trim electrically with resistors . Too lazy ....

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On 6 Jan 2018, at 6:03 pm, John Holst <jholst@xxxxxxxxx> wrote:

There is one final link in this set up and that is the curved angle of the rod that holds the float. When you check the resistance on the bench of the sending unit you would have unlimited movement and the extreme full/empty readings should be correct, 75-15 ohms ~. When you install the sending unit inside the tank and button everything up and fill the tank hopefully the gauge will read full. The first time we did this we had to adjust the rod to just touch the top of the tank to read correctly. Took a slight adjustment to get this right since the gauge read 3/4 full when the tank was really full. The rod was too straight and the float hit the top of the tank before the tank was really full. Just added a bit more bend to the rod and was able to get this right. Unfortunately you cannot remove the sending unit with a full tank and will have to drain down to about half full and start over. Have done this three times thru the years. A 12 v transfer pump helped in this process and filling and unloading the tank was fairly simple. The third Chinese made sending unit came with gaskets that were not usable. Found a gasket/nut set on line or $6.00 PPD. that worked beautifully. The last time the hole for the sending unit was corroded enough to not stop a leak and also added a new tank to the process. Once we also found that the connection to the sending unit for the blue wire was rusty and had to be cleaned up and replaced with a SS nut instead of the plastic plug connector. John Holst..

I once read online that all the old Beast drivers usually carried 3-5 gallons of fuel in a trunk can because you were never sure what the gauge said was correct.

On 1/6/2018 8:01 AM, John Grady jkg@xxxxxxxxxxxxxxxxx [Chrysler300] wrote:

Hi Tom There is an o ring where the filler pipe slides into the tank ;in a groove in the tank . usually in pretty good shape , but can get new one. Judgement call . Do not use o ring from cheap kit in red o ring box. ( China) Must be gas resistant . . Possibly grease the pipe after thorough cleaning ( front end grease ).

How is the cork ? I recently replaced the cork with Ford style little brass tank gas float by using # 12 building wire solid, and solder , cut off arm wrap loop around brass tank groove. Clean arm end till shiny wrap wire around it and solder . I also soldered quickly to little tank . Cork can sink . Has to move in same arc thought center of float . Check sender with ohm meter , not the same ohms as common later (60 up) thermal gauges.( 10-90) Mine was 20 to 200 ohms . It was ok , but corroded connection . I also solder a ground wire to the gas exit pipe where it leaves flange and ground that to car sheet metal . Common problem with fuel gauge is poor connections here .

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On 5 Jan 2018, at 5:53 pm, Tom Chvapil tomchvapil@xxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

Good morning,

We pulled the gas tank out yesterday (to fix the pick up tube sock and sender), and in the process the filler tube separated from the tank. Is it designed to do this, or should it be part of the tank?

If it is separate, is there a seal or??? that needs to be used to make sure fuel doesn’t leak out when filling the tank, or bouncing on my dirt road with the tank full?

Any input will be appreciated.

Thanks,

Tom

Tom Chvapil

tomchvapil@xxxxxxxxx