webcraft
Well-Known Member
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Does it just mean the connections are the wrong way round?
- W
Does it just mean the connections are the wrong way round?
- W
If a fuel gauge shows full when the tank is empty . . .
- Thread starter webcraft
- Start date
prv
Well-Known Member
It can mean that it’s the wrong type of gauge for the sender. There are two common standards, sometimes called “US” and “European” though it’s not quite that clear cut.
Pete
Pete
Bilgediver
Well-Known Member
What did you do since it last worked? If you bought a new gauge it could be the wrong type. As another poster said there are various gauges around and they are often used with a variable resistance sender. Some systems operate with the sender at high resistance for a full tank and some with the sender at low resistance for a full tank.
If you put fuel in the tank and the needle goes to a lower reading then you have a mismatched sender and gauge. Just have to learn that full means empty and empty means full.
If you put fuel in the tank and the needle goes to a lower reading then you have a mismatched sender and gauge. Just have to learn that full means empty and empty means full.
RichardS
N/A
If it shows full all the time it could just be a bad connection/broken cable, depending upon what type of sender/gauge it is.
Richard
Richard
Dan Tribe
Well-Known Member
Mine showed full when the negative side came adrift.
Martin_J
Well-Known Member
UK senders show full with a bad connection..US show empty with a bad connection ... Not the best for us UK boaters...
simonfraser
Well-Known Member
yep full with a dud connection, clean the connectors up. who i their 'right' mind designed that ??!!!
my floorboards on top of the tank were sikkaflexed down and screwed down with laminate glued on top ...
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mlines
Well-Known Member
Or stuck.
We had the opposite problem, showed empty when full. Float had sunk
We had the opposite problem, showed empty when full. Float had sunk
Norman_E
Well-Known Member
Anyone remember driving an early VW Beetle? The fuel gauge would show full until you had used most of a tank, then suddenly drop. Whether it was the gauge or the tank shape that made it work like that I don't know, but my boat is much the same, showing full until about half a tank is used.
matthewriches
Well-Known Member
The 2 main types of in tank senders are resistance or milliamp. Generally on pleasure boats they'll be resistance 0-180 ohm or 240-30 ohm there or thereabouts; the former being "euro". Although different manufacturers may use their own scale as Vetus sometimes does.
Quickest thing to do if the sender is accessible is to pull it out and flap it up and down. Some are on a shaft and slide up & dow, some are on an arm.
I ended up putting in all new senders and monitoring equipment in my own boat as the old ones were unreliable at best.
Quickest thing to do if the sender is accessible is to pull it out and flap it up and down. Some are on a shaft and slide up & dow, some are on an arm.
I ended up putting in all new senders and monitoring equipment in my own boat as the old ones were unreliable at best.
matthewriches
Well-Known Member
A side note... The outputs may differ if you have dual helms as you cannot simply put resistance gauges in line and end up with the same reading!
Mistroma
Well-Known Member
Not certain what you mean here. I think you are talking about duplicate instrumentation at each helm position, not the fact that there are twin wheels.
OP might also check if there's an inline fuse at the sender, it could have gone. A bad connection is much more likely as the current is very small and unlikely to blow a fuse unless something pretty unusual happens. Bad connections happen frequently on these senders.
Mine would sometimes give pretty random readings until I tightened the connectors up and used some Contralube.
The sender still physically sticks sometimes and readings are incorrect even without electrical issues. I'm trying to sort out something better.
lpdsn
Well-Known Member
Same here. Caused by the shape of the tank. Must be a German thing. A reading of half full means nearly empty.
ghostlymoron
Well-Known Member
Try a stick.
Not certain what you mean here. I think you are talking about duplicate instrumentation at each helm position, not the fact that there are twin wheels.
OP might also check if there's an inline fuse at the sender, it could have gone. A bad connection is much more likely as the current is very small and unlikely to blow a fuse unless something pretty unusual happens. Bad connections happen frequently on these senders.
Mine would sometimes give pretty random readings until I tightened the connectors up and used some Contralube.
The sender still physically sticks sometimes and readings are incorrect even without electrical issues. I'm trying to sort out something better.
Mistroma
Well-Known Member
Might be a problem getting it down the 3+metres of hose from the filler and then turning 90 degrees to dip the tank. I could lift the berth cushions, open the hole for the sender and dip it at that point. However, the tank tapers from front to back in width and depth. The base is slightly curved and it has a wide central pillar acting as a baffle. Working out the depth from a dip would require some calculation. It isn't very convenient either .
My present system works well enough, usually accurate to within 1-5 litres over most of the range. The last 20 litres is pretty inaccurate and usually shows 10 litres more than actual. The top end is only accurate to about 75% and then it just jumps to 100% fairly quickly. The potentiometer is obviously too close to the end of the track at that point.
Sticking is the main problem. I should be able to adjust the arm and re-calibrate to give decent readings between 5% - 95%. I might replace the sender and re-calibrate again but am wondering if I can build a better sensor. Not a stick
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