Re: [DML] Fuel Sender or the Gauge?

[mike clemens <rmclemns@xxxxxxxxx>]

Hi Sal,

Since no one else responded, I'll give you my
thoughts.  I've got three transmitters taken apart and
sitting in front of me.

All three exhibit a tendency for the rheostat wire to
slide to the bottom of the post that it is wrapped
around thus ending up with too many turns at the lower
end of the scale.  The wire does not appear to be
glued to the post, probably so the metal slide will
make good contact.  You can slide the wire back up the
post with your fingers, but I have found that gravity
will eventually cause it to fall back to the bottom.

My resistance readings are from one ohm to 100 ohms
one all three.  I don't have any voltage readings at
this time.  You can contact me offline if you have any
questions.

Mike


--- Steelwings <steelwings@xxxxxxxxxxx> wrote:

> I'm having a problem with either my fuel sender or
> the gauge. I was hoping someone on the list might
> give me the benefit of their experience with this as
> I can find almost nothing in the archives. Here's
> what is happening: I have a stock, 1981 original
> gauge and sender. My tank is about half-full. The
> fuel gauge is indicating an "above full" reading
> with the low fuel warning light dimly lit. (The
> needle is at the 12:00 o'clock position) If I remove
> the sender and allow the float inside to fall to the
> bottom of the tube, the needle will drop to the
> "empty" mark and the fuel warning light will
> illuminate normally. If I manually bring the float
> up approximately 1/4 of its total travel up from
> bottom, the gauge will read "Full" and any linear
> increment below that point will deflect the needle
> accordingly.(for instance: 1/8 of the total travel
> from the bottom reads "half-full") I have removed
> the sender and examined it visually both inside and
> out. It appears to be in almost new condition. No
> visible damage, no varnish or discoloration of the
> plastic or metal components. The float and wipers
> travel freely along the "rheostat" winding. The
> windings appear to be evenly spaced and undamaged. I
> placed a VOM across the wiper lead and winding lead.
> At the bottom float position, it reads about 20ohms.
> At the top float position, it reads about 100ohms.
> Sliding the wiper along the winding , the readings
> are linear. Then, in circuit, I took a voltage
> reading across the leads. Black (ground) to Red
> (Power) was approximately 12.5VDC. Then I checked
> across black to yellow (the return) and I got the
> following: With the needle on the gauge reading
> "full" (4/4ths) with the float approximately 1/4 up
> from the bottom of the tube, I read 6vdc. (That is:
> 6 volts to cause the deflection to read exactly
> full) at 1/8th the travel from the bottom, 3 volts
> and so on. If I go beyond quarter of the way up from
> the bottom, the voltage exceeds the 6 volts and the
> needle will deflect beyond the full mark and
> continue counter clockwise until it can't go any
> further. All the way up (full travel) was about
> 10vdc.  The circuit looks pretty simple but the
> books don't give me any reference measurements to
> compare. Has anyone ever measured the resistance of
> the travel in the stock DMC sender? How many volts
> will cause a full deflection in the gauge? Any
> Ideas? Is it the gauge or the sender? Thanks in
> advance for any advice you guys might have.
> Sal
> 
> 
> [Non-text portions of this message have been
> removed]
> 
> 
> 
> 
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