Date:         Thu, 19 Apr 2001 15:21:14 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: 89 - Fuel/temp/speedo
Comments: To: Marcus Ward <marcusward@MSN.COM>
In-Reply-To:  <NFBBIHBOALHPLHFCLJCOAEEICBAA.marcusward@msn.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 01:21 PM 4/19/2001, Marcus Ward wrote:
>1. I am considering replacing my fuel tank sender unit because the fuel
>gauge is reading low.  I have replaced the voltage regulator and tested it.

Meaning, you measured it at ten volts +/- half a volt?

>I have grounded the fuel gauge and it reads full quite quickly when I do so.
>Sender is left?  How sluggish is the fuel gauge normally?

The gauge takes maybe a minute to reach a final reading, might be more at
very low readings.  Also may need to be tapped or vibrated to come to final
reading (the engine usually takes care of that) -- oil on the pivot may be
useful, don't know.  You have to remove the gauge completely to get to that.

The test box mentioned in Bentley is *not* calibrated in ohms but in some
arbitrary VW unit.  I've measured one gauge that AFAIK works reasonably --
at ten volts, it takes 250 ohms for bottom of the red, 150 for top of the
red, 110 for one quarter, 75 for one half, 40 for full.  You could make up
test resistors of 250 and 40 ohms to see how that corresponds to
yours.  The specified limit in Bentley is +/- one needle width at both top
and bottom -- I suspect that they're typically closer than that but don't
know for sure.  Changing the input voltage to 10.5 or 9.5 moves the needle
about one needle width at full scale and somewhat less at top of the red.

Grounding the gauge for any length of time will produce an overheated smell
and will probably change the characteristics of the gauge somewhat.

david


David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"