HZ Tank Sender Unit
Page created by T Nov 24th 2008:
HZ Tank Sender Unit:
Fuel Tank Starlock Washer:
The Fuel Sender is held in the tank by a rotatable ring called a Starlock Washer.
Fuel Tank Sender Repair Contact:
The Sender Unit consists of a hinged float connected to a Variable Resistor.The height of the Float determines the Resistance of the Variable Resistor. The lower the Float the higher the resistance.The higher the Float the lower the resistance.
The Station Wagon Sender unit can only be removed and replaced with the Fuel Tank removed or lowered from the car since there is no access panel in the floor of the Wagon.
Fuel Gauge:When the Tank is full the Sender has the least resistance. This causes maximum current to flow through the Fuel Gauge and makes it read full. When the Tank is empty the Sender has the most resistance. This causes minimum current to flow through the Fuel Gauge and makes it read empty.
Removal:The Sender Unit is held in the Tank by a round Retainer Ring. The Ring is tapped with a Screwdriver and Hammer in the anti-clockwise direction until the indents line up. Remove the Ring and then the Sender Unit can be removed.It is necessary to rotate the Sender as you pull on it to make it exit the Tank.
Readings:Resistance readings from a typical unit.Full 18 OhmsHalf 40 OhmsEmpty 80 Ohms
The Wiper in the Variable Resistor has a brass contact mounted on a steel spring . Over time the spring steel becomes resistive. It should have a resistance of 0 Ohms but over time becomes very high, typically in the thousands of Ohms (Kilo Ohms). This causes the Gauge to under read ( i.e. shows half when full).The Variable Resistor can also become too high in value, possibly caused by lack of Fuel covering the Variable Resistor as when the Fuel level is kept low.
The repair is to solder a Wire between the Wiper and the Wiper Pivot which brings the Wiper's resistance back to 0 Ohms.The 3 tabs that hold the housing together are bent back to gain access to the Wiper.If the tabs break the 2 halves can be soldered back together. The Star Washers that hold the Conductor Strip in place can be removed and replaced with a Narrow Blade Screwdriver. Going around in a Clockwise direction, progressively poke the Screwdriver under the Star Washer, lifting slightly once the Screwdriver Blade has fitted under.By the time you've gone round the Star Washer three times it will be free of the Brass Shaft.The Star Washer presses back on again with pliers.
Installation:First fit the rubber O-Ring Seal between the Tank and the Sender Unit.The Sender has to be installed Float first, then the filter then the rest of the Unit. It is necessary to rotate the Sender to get it all the way into the Tank and facing in the right direction. The Output Pipe should be facing towards the front of the Car when the unit is properly located.
There is a rotational Ring that has to be inserted between the Tank (outer) and the Sender (inner). The Ring is tapped with a Screwdriver and Hammer until it seats properly with its vertical Tabs hard up against the Outer Ring.