Fuel Gauge Flutter

Hi all -- posting to both saloons & xks because the problems apply to both types of cars. Mine is an original Mk IX, 792817 BW, with twin fuel tanks. Since I got the car in Feb. '89, the left tank fuel reading has done a VERY fast flutter of gauge needle when less than full (right fuel reading is OK and stable). Last week, the fast flutter wound up snapping the needle off right at the point where it hits the stop; gauge still reads but with only 1/2 of a needle! So I went after it, starting yesterday -- removed the instrument veneer panel, removed the glass cover on the fuel gauge by unscrewing the black rim, fished out the broken part of the needle (about 1/2"), bent the needle out a little, glued the broken piece in with a drop of contact cement, then superglue, then recoloured in flat white. I also superglued a small piece of rubber in at the needle stop so if it flutters again it hits rubber instead of metal. Tested, read OK, then filled both tanks again and did about 10 miles, still reading OK. The only problem is the needle now shows (with a small "lump") where I did the repair. So today, I went to reinstall the instrument veneer panel, only to discover that the switch rod for the headlamps was pushing back into the dash, so I couldn't press the chrome knob on. So -- removed both under-dash panels and radio to get to headlamp switch, discovered that the plastic had broken loose from the metal housing -- used a big pair of vice-grips to press-fit them back together; reinstalled switch; rod now appears to hold with pressure. Decided enuff for tonight, will (hopefully) finish tomorrow. Two questions: (1) I have an identical fuel gauge (Smiths FG 2230/00, confirmed by my Mk IX Spare Parts Catalogue) which looks perfect, from my spares car, 791118 BW, an Alabama rustbucket too far gone to restore -- since I'm this far down anyway, should I install the spare gauge, or leave the original with the little lump on the needle (which a concours judge may gig for 1/10 point)? (2) re: the needle flutter -- my friend Jerry Theis (54 Mk VII, '61 Mk IX) thinks the flutter (which caused the needle to break in the first place) can be caused by either a bad electrical connection at the sending unit, or by worn contacts inside the sending unit -- the fix is to drain the tank (left on this car), drive home on the right tank, then remove the sending unit and clean everything thoroughly. Does this sound like the right thing to do? Any help from anyone is really appreciated - Larry Martz

Larry: It would be your choice on swapping the gauge; it sounds like a lot of work. I'd be surprised if any judge gave your "repaired" needle a deduction. As to the fluttering, I would suspect excessive wear or dirt on the movable wiper or the winding of the tank unit. Cleaning may help. A loose wire would more likely cause intermittent operation instead of a flutter. You should be able to do a perfunctory check of the (removed) tank unit using a volt-ohm meter conected across its terminals. See if the resistance increases and decreases smoothly as the float is slowly raised and lowered. Erratic V/Ohm needle movement would indicate a bad spot(s) on the winding. Good Luck - Dick Cavicke

Hi Dick & all -- TNX for your comments re: checking the movable wiper. My good friend Jerry Theis ('54 Mk VII) suggested that; he says have the float unit out and clean the contacts gently but thoroughly -- unfortunately, I topped off the LH tank again while checking this out, so will have to wait 'till it's empty again to get the float out -- I appreciate your comments -- Larry Martz

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