[Chrysler300] RE: Sender/gas tank pickup

["'John Grady' jkg@xxxxxxxxxxxxxxxxx [Chrysler300]" <Chrysler300-noreply@xxxxxxxxxxxxxxx>]

Hi, J-Y,

Decided to send this exchange to list server, lots of hard earned info about
gas gauge in this, might help others. "More than you ever wanted to know
about gas gauges" ; taking tank in and out gets ,er, boring, fast..and
messy. 

By being sure when float is down in bottom of tank you have 70-75 ohms and
10 to 15 ohms when up (up , or F accuracy, less important than 70 down,
which is the E reading accuracy value ) Then you know tank and float etc are
all perfect; any problems are elsewhere. Do not bend arm ,unless with full
understanding. Be sure tank body is grounded well. Later Dodge trucks have
ground wire on lock tab area , so problems happened ..add brass screw and
bolt,. Wire to frame? Some repro senders do not work right, ohms are off.
Bad ground = gauge stays on E. Or drops to E .

To test wiring short wire at tank from the gauge on dash to frame at back
for 5 seconds or so  , gauge should go up; if not,  problem is at dash
gauge, regulator, or wire or bulkhead plug ; if it does go up, but was stuck
at E before,  problem is in tank or ground of tank no good. 

 Actually , J-Y, I had forgotten what we did---on opening all this, dropping
tank again,  to see why the 40 ohms max at E ,(we thought float was hung up)
instead of 70, we see we had reworked that Matador sender long ago to get
the 3/8 pickup ; it had a new sender box MIG welded (!) to a new 3/8 pickup
pipe, and a homemade filter screen of metal mesh on pipe end . That sender
box,  on the one on there,  (box with fine wire winding) came from some
other vintage or make car; it is,  from its factory equipped with only 40
ohms of winding, total--which is wrong . Arm was moving correct amount etc
but wrong resistor winding ; we had 4 NOS F senders , checked them all 10-15
to 65 70 ohms (correct numbers) ; one NOS MOPAR of unknown application, with
cork float  went like 20 to 200? Early car? 40's-50's?

We used one of the NOS F to replace it,  although now back to 5/16 tank
pickup, which is probably OK. Based on my own experience and Jamie's we left
plastic basket filter off of pickup pipe, added a plastic in line clear one
at tank outlet. I do not like this, probably paper filter more restrictive
than tank mesh, not good to restrict pump suction side , but we know that
mesh falls apart or swells in alcohol, closing up the holes, clogging inside
the tank--a worse problem. This way you can see and fix in a few minutes. I
did this on many Packards, rust particles from tank on those make fuel pump
valves stick open.  Discussion with Ed,  all his lawnmowers and garden
tractor etc had failed, swelled  fuel lines this year..this stuff is BAD; I
think it gets the earlier gaskets at fuel gauge port , too, causing leaks
with full tank . Last 6 gallons are above sender port (ask me how I know
that) . NAPA ones junk, they swell, as is kit they sell for tank, lock ring
is thin, low quality,  easily bent metal and too small diameter. So save and
fix old MOPAR one.

I have a Moroso race filter , about 4" long aluminum filter with stainless
mesh in it. 3/8 too, female pipe thread ends.  You can open and clean, that
is the right thing for at tank , but 80$ or so, (auugh)  and ordered for
hemi project, not this. (Summit). May get another one for this.  Correct way
to deal with eliminating nylon mesh and alcohol fuel. All tank gaskets now
seem suspect ...

I have found opening that sender resistance unit..which I will do later on
this one ,(to see about the 40 ohms)...  almost always bends the little
slider which is quite critical in pressure on windings..if too much,  it can
hook on one wire of winding, hanging up or breaking, or wear out very
fast..often worn to nothing  ; although I have done so in past, trying to
repair it, I do not think I will ever open one again( three little
tabs..leave alone) ..too easy to break or bend it while opening it, a
critical thing . If intermittent in car or hanging up, you have to write it
off..or you spend a day messing with it , another half day exchanging tank,
only to have it screw up a week later. Sometimes little box is full of rust
....

On calibrating gauge, if tank is 70, empty, it should read E; if gauge
regulator is pulsing, probably ok, but that impacts temp and oil gauges too,
so all will be high or low if that is defective. If it sticks it can burn
out all the gauges , by putting 12 volts on what is supposed to be about 5 v
average (averaged by the pulsing 12V on and off), usually gauges are OK,
unless someone messed with them, in my experience. But many ARE messed with.


The little brass tanks are available from Ford parts, a pack of two.

The plastic liner someone put in this tank looks good; I have had bad luck
with that, it falls off in sheets, despite doing exactly what it says. Do
not trust it.

John Grady

-----Original Message-----
From: Jean-Yves [mailto:jymopar@xxxxxxxxxxxxxxx] 
Sent: Wednesday, June 18, 2014 7:26 PM
To: 'John Grady'; ncrdawgn@xxxxxxxxxxx
Cc: 'Jamie Hyde'
Subject: RE: Sender

I think we used the original sender or a used one I had here? 5 years ago no
repro tanks and senders? So I must have used an original sender since we
used an original tank...Float may work perfectly, but sender is made of all
very thin wire ,  brass thin plate that rubs against that may not touch
perfectly all the way?... Why ohm does not go above 40?

*** J-Y, if it does not touch, it goes to thousands, infinity , jg---or if
far end grounded (some are) to max of 75 or so 
J.Y.

-----Original Message-----
From: John Grady [mailto:jkg@xxxxxxxxxxxxxxxxx]
Sent: June-18-14 4:08 PM
To: ncrdawgn@xxxxxxxxxxx
Cc: 'Jean-Yves'; Jamie Hyde
Subject: RE: Sender

Ed, That is wrong ohm value sender..is it a repro sender? Maybe J-Y
remembers; this means we have to measure any repro senders, As installed.
..same one must be in red 2wd dodge truck tank, does inverted version of
same thing .
only takes 8 gallons when on 1/8 .

But pipe is at right depth. 

Any one of those old F ones would work, 15-70 closest to spec , be sure
float is OK ,and that suction pipe ends up where the one you are taking out
is , in depth in tank . 


~15 ohms F ; 70 E ; spec is 10.3 and 73 ohms I think..used for many many
years by MOPAR

-----Original Message-----
From: ncrdawgn@xxxxxxxxxxx [mailto:ncrdawgn@xxxxxxxxxxx]
Sent: Wednesday, June 18, 2014 2:07 PM
To: jkg@xxxxxxxxxxxxxxxxx
Subject: RE: Sender

It looks like the sender/ meter  was reading correct. ( but wrong value!)
After taking it out it is reading 2.5-40 ohms. We have three more senders of
that type. They range from;

1) 15-65 ohms
2) 15-70 ohms
3) 22-80 ohms

Which sender should I put in?

Ed


---------- Original Message ----------
From: "John Grady" <jkg@xxxxxxxxxxxxxxxxx>
To: <ncrdawgn@xxxxxxxxxxx>
Subject: RE: Sender
Date: Wed, 18 Jun 2014 12:40:37 -0400

Float must not be dropping to bottom of tank , bringing ohms to 70 or so? If
it worked outside the tank, arm travel is screwed up, not the sender
resistor; (***this is wrong,  meter was misadjusted first time, outside
tank) this is why it never goes below 1/8, ohms never go over 40, float does
not drop enough ? Or is hitting pipe ? Yes we have to open and look at why
it does not go to far end of resistor . I do not know what you mean .2?
you mean zeroing it, right? .2 ohms on X1 is Ok, close enough to zero (it is
.2 compared to 10 or 70, not an issue; BUT--not really linear like that,
but you get it; accurate zero setting impacts low readings more , like the
10 ohms or less on X1, but critical to zero the ohmmeter by shorting leads
on scale you are using each time . At least not a damn digital meter which
will jump all around due to (normal) intermittent contact of swing arm with
housing (the ground of swinging arm is not good..way it is made--but works) 

-----Original Message-----
From: ncrdawgn@xxxxxxxxxxx [mailto:ncrdawgn@xxxxxxxxxxx]
Sent: Wednesday, June 18, 2014 12:26 PM
To: jkg@xxxxxxxxxxxxxxxxx
Subject: Sender

Hi John,

No leaks from tank. I checked the sender in the tank the ohms are between
6-40. The ohms are still 40 with the tank in place. I haven't added gas yet.
I checked the meter when I got back. It was at .2 on the X1 scale when I
took the reading outside the tank (3-50 ohms). 

Do you want to change the sender?

Ed



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Posted by: "John Grady" <jkg@xxxxxxxxxxxxxxxxx>
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