Re: Is my Gas Gauge Bad?

["Gregory S. Youngblood" <greg@domain.elided>]

On Fri, 17 May 2002, Jon Durham wrote:

> Gas gauge doesn't function on my 74 Spider. I've tested the sending unit
> with an ohm meter and it seems fine. I've switched the wires (pos and
> neg) from the unit
>
> Fixes?

Did it work before, or has it ever worked since you've had the car? If it
did work before, did it work correctly? And, if it worked before, did it
start behaving odd before it failed?

I've got a similar problem on my 74 Spider - it reads at most 1/2 a tank,
and it varies wildly between E and 1/2 while driving. Even revving the
engine will make the guage climb. :)

Previous answers to that same question that I posed were to check the
ground wire from the sending unit at the tank. Or to install a new wire
that you knew was definitely going to a good ground. Checking the wires at
the guage is also a good idea.

I've also noticed a gentle tapping on the guage will sometimes wake it up.
If I didn't know better I'd almost think there was a mechanical interface
between the fuel guage and the float in the tank. ;) Actually I think my
guage has a lose wire or dirty connection.

Keep in mind I haven't repaired this myself yet, so I'm only relaying the
answers kindly given to me a couple of months ago.

One more thing - I don't know the electrical system in the Spider, but I
do know that in a lot of DC based circuits if you reverse polarity then
you will now need to start replacing things.

Perhaps someone else here on the digest knows if you potentially damaged
your guage or anything else when you reversed the wires. If the guage
works like a lightbulb and there is nothing else in the circuit, your
probably ok.

Here's a silly question, perhaps you already checked, but have you checked
your fuse panel for any blown fuses? Surely the guage is on a circuit
shared with other items so you should see more than just the gas guage
fail if it were a fuse, but it can't hurt.

Good luck,
Greg
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