Fuel Gauge testing
Posted: 28 Aug 2011 17:36
So, here's the deal! The sending unit is actually two switches in one. A contact switch for the low fuel level warning light and a potentiometer for the fuel level gauge.
1976-1979
1980
The green/orange wire is for the low fuel light.
Current comes from the light in the panel to the Delay unit (attached to the instrument pod) then through the green/orange wire to the fuel level sender. At the sender the circuit is completed to ground when the float ROD touches the ROD STOP TAB. Testing the circuit. Let the float rod rest on the stop tab for at least 30 seconds, then check the dash for the Low Fuel light. You can also remove and ground the green/orange wire, after 30 seconds the light should come on.
The Green/black is for the fuel gauge.
Power comes from the gauge in the pod directly to the fuel level sending unit. The potentiometer gives full current to ground when the arm is at it's high point As the arm drops, the resistance in the circuit changes and changes the the reading on the fuel gauge.
Testing the gauge. Disconnect the green/black wire and make a good contact to ground. If the gauge reads full, then the gauge is good. If it reads 3/4, install a new gauge.
Once a new gauge is installed and with the sender out of the tank, you can adjust the float rod stop tab to give a better reading. Holding the sender unit in the correct position as it would be mounted in the tank, take a reading off the new gauge with the float rod resting on the stop tab. If the gauge doesn't read empty, then carefully bend the rod stop TAB down in small increments until the gauge reads empty.
Lifting the float to it's highest level should give you a full reading. There is no adjustment at the sender to give a higher reading.
Clay
[url="http://web.me.com/jclaythompson/Site/Welcome.html"]My Triumph Site[/url], [url="http://web.me.com/jclaythompson/Technical"]Technical Stuff[/url], [url="https://public.me.com/jclaythompson"]My Public Folder[/url], [url="http://web.me.com/jclaythompson/tr8/Welcome.html"]My TR8 Site[/url]
1976-1979
1980
The green/orange wire is for the low fuel light.
Current comes from the light in the panel to the Delay unit (attached to the instrument pod) then through the green/orange wire to the fuel level sender. At the sender the circuit is completed to ground when the float ROD touches the ROD STOP TAB. Testing the circuit. Let the float rod rest on the stop tab for at least 30 seconds, then check the dash for the Low Fuel light. You can also remove and ground the green/orange wire, after 30 seconds the light should come on.
The Green/black is for the fuel gauge.
Power comes from the gauge in the pod directly to the fuel level sending unit. The potentiometer gives full current to ground when the arm is at it's high point As the arm drops, the resistance in the circuit changes and changes the the reading on the fuel gauge.
Testing the gauge. Disconnect the green/black wire and make a good contact to ground. If the gauge reads full, then the gauge is good. If it reads 3/4, install a new gauge.
Once a new gauge is installed and with the sender out of the tank, you can adjust the float rod stop tab to give a better reading. Holding the sender unit in the correct position as it would be mounted in the tank, take a reading off the new gauge with the float rod resting on the stop tab. If the gauge doesn't read empty, then carefully bend the rod stop TAB down in small increments until the gauge reads empty.
Lifting the float to it's highest level should give you a full reading. There is no adjustment at the sender to give a higher reading.
Clay
[url="http://web.me.com/jclaythompson/Site/Welcome.html"]My Triumph Site[/url], [url="http://web.me.com/jclaythompson/Technical"]Technical Stuff[/url], [url="https://public.me.com/jclaythompson"]My Public Folder[/url], [url="http://web.me.com/jclaythompson/tr8/Welcome.html"]My TR8 Site[/url]
