Any adjustment on old dial fuel gauge?

Cpeek007

Recruit
Joined
Jun 28, 2010
Messages
4
With new fuel sending unit float all the way down it still shows 1/4 tank on fuel guage. When I raise float up it goes past full when only up about half way. Is there a way to adjust guage?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Any adjustment on old dial fuel gauge?

No. You adjust the float arm and/or float position on the arm. You need to actually install the unit to see where you are at. Adjust for an accurate "empty" reading because you know when the tank is full as you filled it. Because of how fuel tanks are built and how senders are made you cannot get really accurate readings across the entire band. And remember, a fuel gauge is a fuel "level" gauge not a fuel "quantity" gauge. If you look at a cone shaped cup, there is much more stuff in the top half than the bottom so shape of the tank has the same characteristics.
 

wire2

Lieutenant Commander
Joined
Jun 25, 2007
Messages
1,584
Re: Any adjustment on old dial fuel gauge?

All fuel senders have a specific resistance range. There are several different ranges. It has to match the gauge or you'll never get proper empty to full indication.
A fuel level gauge is just a voltmeter that measures between +12v and ground through the resistance of the sender.

If the old sender is damaged/lost, you can "read" what range your gauge wants with a potentiometer (volume control) from an electronics supply and a multi meter.

Get a pot rated at 500 Ω, connect the left post to the sender connection of your gauge, the middle post to ground. Key on, slowly turn the pot until you see an "Empty" indication on the gauge. Remove 1 wire from the pot, read the resistance between the left and middle posts.

Connect the wire again, then turn the pot to get a "Full" indication. Remove the wire, read the resistance of the pot. Now you have the lower/upper range of the sender your gauge wants. An error of ? 10% is no biggie.

Here's an article on automotive senders/gauges listing some common ranges;
http://www.summitracing.com/expertadvice/professoroverdrive/default.aspx?techQuestion=3679
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Any adjustment on old dial fuel gauge?

No need to go through all that. American marine fuel senders are 33 - 240 ohms (full-empty respectively). International units are different. Yes - the gauge and sender need to match but again, American marine fuel gauges are equally standardized.
 

wire2

Lieutenant Commander
Joined
Jun 25, 2007
Messages
1,584
Re: Any adjustment on old dial fuel gauge?

No need to go through all that. American marine fuel senders are 33 - 240 ohms (full-empty respectively). International units are different. Yes - the gauge and sender need to match but again, American marine fuel gauges are equally standardized.
Agreed. But the OP apparently has a non standard sender or gauge, most likely the former.
 
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