On Thu, 21 Feb 2008 07:13:52 -0700, ED
wrote:

Burning project of the moment is a dead fuel gauge sys on the ol'
farm tractor. 70's vintage IHC lots of german made cast iron for
those appreciating that type of stuff.. Anyhow I condemened the
origional components and with a Napa gauge and sending unit kit
I can get it to work ok but I get a higher reading on the gauge then
is indicated..IOW the gauge reads 1/2 full when it should read empty.

Any tricks to get around this that anyone like to share? Some sort
of E magic or is it a case of throw away and try again.. I did do
some neat metalworking to replicate the OEM sender....hate to waste
that.. ED

Even if you got both the sender and gauge from NAPA on the same
order, somebody botched it reading the catalog and they didn't give
you a matched set - go back and raise a ruckus if necessary.

There are a dozen different resistance range systems for gas gauges,
including from memory the most popular 260-0 ohms, 72-0 ohms, 0-90
ohms (backwards - 0 at full 90 at empty)...

The gauge companies make multiple identical-looking gauges for the
various systems, only the part numbers are different - so you can put
a Stewart-Warner or VDO cluster in a car with a GM or Chrysler or
Toyota or Mercedes (or whatever) factory sender without dropping the
tank and changing the sender. Or senders for dual tanks.

If it's an aftermarket 2-1/8" style gauge it's probably a lot easier
to change the gauge end, once you figure out the one you really need.
If you are trying to use a factory gauge movement in an instrument
cluster, then you have to change to the right sender range.

Never heard of any "magic bullets" to fix that mismatch, and they
would probably cost more than the right gauge movement.

-- Bruce --