Date:         Mon, 23 Jun 1997 23:38:54 -0700
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         Ari Ollikainen <ari@interserve.com>
Subject:      Re: Fuel Gauge inaccuracy(pessimistic vs optimistic)

Jim Thompson wrote:
> 
> Ari -
> 
> Vanagon gas gauges have a notorious habit of becoming "optimisticly"
> inaccurate when the fuel level gets low and close to the red zone
> (so-called reserve area) of the gauge.  Generally speaking from the
> owner's manual, when the needle hits the red you're supposed to have 2.5
> gallons left to get yerself to a gas station.  I've seen it dip as low as
> half-way thru the red zone on the gauge.  However when the tank finally
> empties out, the sender (or the gauge - or both I really don't know) has
> the habit of causing the needle to slightly drift back up showing just
> over a quarter of a tank of fuel left to drive on.
> 
> This has happened in my 80 Vanagon (now sold off) and I have a few other
> friends with Vanagons that this has happened to as well.  When your tank
> empties out (as you and maybe others have found out already), the van
> starts to slow down due to the lack of fuel slowly becoming unavailable
> in the FI system.  Because the fuel is used to "cool" the fuel pump,
> running it dry can (but not always) overheat and destroy the pump.  An
> area to be very careful as pumps are NOT cheap.

	A quarter to half mile of travel won't hurt the pump...been there, done
that!
	(including Sunday)

	Having a history of 35+ years of VW ownership including the first model
('62)
	with a fuel gauge I can, anecdotally, report that NONE (zero, zip,
nada) have 
	exhibited "optimistic" behavior...they have all reported LESS fuel
remaining
	(ie. PESSIMISTIC readings) than acually remaining in the tank! The
sample 
	includes: '62 112, '64.5 Porsche 356SC, '66 Westfalia, '68.5 Bug
w/autostick, 
	'69 Westfalia, '71 Westfalia, '73 Westfalia, '75 VW-Porsche 914 2.0, 
	'81 (basic) Westfalia, '85 VanagonGL, '85 Westfalia, '86.5 Scirocco16v, 
	'91 VanagonCarat...

	HOWEVER, EMPTY, as beyond the RESERVE (or "red zone") or almost pegged
is 
	pretty much fumes remaining in the tank. 

	The ONLY exception is the current '91 Westy under discussion. In
otherwords, 
	the behavior of the fuel gauge is decidedly NOT normal!
> 
> Don't always trust the gauge.  I use the odometer and the gauge as a team
> to keep track of the fuel and of course the mileage I'm getting as well.
> I always fill up between the 1/4 to 1/2 mark.

	Yep...and I said as much in my original post. I ALWAYS reset the trip
odo on 
	fill-up and note the mileage. 
> 
> I might add that the fuel gauges in my 84 Westy, 62 Bug and the following
> formerly owned VW's have always been "optimistic" and never that
> accurate: 67 Bus, 63 Kombi, 69 Camper, 71 9 Passenger Bus, 64 Notchback,
> 73 Panel Bus, 61 Panel Bus (Retrofitted with factory gauge/sender [new] -
> recently seen in Hot VW's now owned by Scott Pearson/WCM), 81 Rabbit PU
> Diesel, 63 Bug, 73 Karmann Ghia (bought that new) and a 59 Euro Single
> Cab PU.

	I think you have to learn the definition of "optimistic"...
> 
> My 73 Toyota PU and 78 "Cheby" Monte Carlo are VERY accurate.

	I have more anecdotal evidence with other car makes which refutes the
idea
	of "accurate"...
> 
> I'm going to acquire a 90 VW Fox Wagon this week (VERY low miles, fully
> loaded).  It will be interesting to see how accurate the gauge is on it's
> trip from LA to Redding.
> 
> My experience has been that the term -  fuel gauge accuracy -  in
> Volkswagens is an oxymoron.

	That depends on how you view it...I'll bet that *most* auto
manufacturers bias
	their fuel gauges to be pessimistic as opposed to optimistic or
accurate to 
	combat the tendency of the average owner to "streeeeetch" the time
between 
	fill-ups.

	I'll bet it's the voltage stabilizer.