how to test a fuel guage
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=46960
Printed Date: 27 Jul 2025 at 1:50pm
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Topic: how to test a fuel guage
Posted By: tractorman
Subject: how to test a fuel guage
Date Posted: 09 Mar 2012 at 5:15pm
I have non working fuel guages on my 185, 190 and Simpicity Sun Star How do i test them so i can get them fixed??? Tractorman ------------- Play on 38 B 49 WF , working on D14, D15 B10, Bee 12 B110. use 185 and 190 |
Replies:
Posted By: Austin(WI)
Date Posted: 09 Mar 2012 at 5:21pm
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First find out if it is the gauge... Ground the gauge and see if it moves...if not the gauge is junk and you need a sending unit. ------------- "Better By Design" |
Posted By: Gerald J.
Date Posted: 09 Mar 2012 at 7:45pm
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I take the sending unit out of the tank. I connect it to the gauge normally and I use a clip lead to ground the mounting flange of the sending unit. Then I run the float up and down by hand to see if the gauge follows. On one of my tractors the wiper on the resistance wire was worn (along with the pivots) so it wasn't touching. I was able to bend the contact to make it ride on the resistance wire coil again and now it works. There are two schemes for a gas gauge, either the resistance rises as the fuel rises or the resistance goes down as the fuel rises. Testing by shorting the sensor terminal to ground gets different results on the gauges with these different systems. In one it pegs the gauge at full, with the other it drives it to the peg at empty. Then with the opposite operation there are several values that have been used for full and empty resistances so gauge and sender have to match to have a useful gauge display. Gerald J. |