Re: [DML] Fuel Sender or the Gauge?

["Steelwings" <steelwings@xxxxxxxxxxx>]

I will be happy to post a digital of the internal windings. I will do this
tomorrow after I get home from work. However, I wish we had a baseline unit
to compare our readings. So far the only responses have been from you and
Mike and I think we all have the same problem. I don't mind springing for a
new sender. I just don't want to buy a new sender only to discover my gauge
is bad. If we could get someone on the list that could give us the impedance
characteristics of a known good unit as well confirm that a 6vdc input to
the gauge would normally cause the needle to deflect to the "full" mark.
>From what I've read, this is a problem that has been haunting Delorean
owners for years. I'm just surprised no one really responded to the thread.
Anyone want to throw us a bone here? Thanks in advance.
Sal
----- Original Message -----
From: "Marv Hein" <marvhein@xxxxxxxxxxx>
To: <dmcnews@xxxxxxxxxxxxxxx>
Sent: Wednesday, November 02, 2005 6:32 PM
Subject: Re: [DML] Fuel Sender or the Gauge?


> I have symptoms similar to Sal's, just no solution as of yet.
>
> In my case, the gauge is also pegged high when full and when it
> starts to come down, it's about 1/2 tank off from reality.  I use my
> 1/2 mark as Empty and the wild fluctuations I get between 1/2 and
> 1/4 as REALLY EMPTY. :)
>
> If you are right, then my rheostat wire has also slipped down, just
> less than his. I am puzzled by your description vs. his statement
> that the windings appear to be evenly spaced.  It sounds like your
> senders do not have this appearance.
>
> Sal, if you want to email me a digital photo of what yours looks
> like, I'll pull my sender and do the same.  I'll be working on the
> tank this weekend anyway, installing new pump boots.
>
> It shouldn't take much to determine if the relative appearances of
> the two senders somehow corresponds to their differences.  Ideally,
> we'd also have a photo of a sender that is functioning perfectly.
> Any volunteers?
>
> There is also the possibility, I guess, that we both have good
> senders and bad gauges.
>
> Marv
> #10820
>
>
> --- In dmcnews@xxxxxxxxxxxxxxx, mike clemens <rmclemns@xxxx> wrote:
> >
> > 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@xxxx> 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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