Fuel Gauge

I'm having a problem with my fuel gauge. It stopped working last week and
when I checked the sender, it was full of gas. After replacing the sender,
the gauge will only read just above empty and the low fuel light stays on.
When I shut the key off, the needle will drop down below empty, but will
never come up any higher than about 1/8th. I know that there is gas in the
tank. Any
suggestions? Regards - Ron, '59 150 dhc

If you drain the tank, I think you might be able to look through the drain
hole and see the float mechanism. If so, you can reach up into the tank
with a stick and gently lift the lever to see if it has free travel through
its full range. If it does, have someone watch the petrol gauge
while you do it to see what the petrol gauge does. If the float moves
properly while the gauge continues to do what you described, I'd check the
resistance in the sender to see if it agrees with a good one. I think the
sender is a variable resistor and the gauge is an ampmeter. Since your
warning light also stays on, my guess is the float is not staying on top of
the petrol. I believe there are baffles in the tank and it might be hitting
one of them. - Bruce Cunningham, '53 XK120 OTS

Ron: Don't throw the old one away, it is supposed to be full of gas by
design. First, try grounding each lead and see if gauge reads full to check
gauge. It's a simple circuit and can be checked with a meter or try using
the old sender with a earth lead attached. If no luck, drain the tank and
remove the sender to see that arm has free movement and that the float
"floats".
Good luck. - Bruce Baysinger

Ron: I would remove the sender again and attach the terminals to your
volt-ohm meter on the bench. Move the float through its full throw and
verify that the resistance changes uniformly. If you don't have a volt-ohm
meter proceed to the next step. Re-attach the gage leads in the car without
installing the sender in the tank and, taking reasonable precautions for
the possible spark and fuel vapor hazard, again move the float through its
full travel while watching the fuel gage reaction. Same problem? Maybe
you've got the leads swapped. The system is fairly simple and reliable
though not terribly accurate.  - Regards, Dick Cavicke

If you have any questions or comments send e-mail to: ted@jag-lovers.org
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