Another good test is to attach the female connector to the unit while it is out of the aluminum tube ( being careful of the thin wires) and slide the float up and down by hand (out of the tank of course) while watching the fuel gauge for smooth tracking and reserve light function at bottom of float travel....Ign. key in ACC position or with the engine running
You must kneel in the seat facing backwards to manipulate the float while holding it in the rear shelf area unless you want to use jumper clips for a little more slack....

Found a couple of dead spots along the float wire path but cleaned them up with fine emery paper.....
Nice way to test unit without the mess after repairs......

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)