I hope you are having better luck than I am... Heres what I have found. First off my boat is a Wauquiez Amphitrite built in 1984 in France
so I am reasonably sure the guages for the water tanks
are on some sort of european standard. I have two gauges which monitor
. I am pretty well certain the problem is that I have the wrong sending unit because the gauge in question reads correctly for the other tank it monitors so does the other gauge on both of its tanks. There is a three position toggle switch to select which of the two tanks I want to check. I replaced the sending unit with a vdo european scale model but this did not help.
Tonight at the boat I took some measurements on the sender that is not reading right and also on one which is. First i measured voltage. When I remove the wires from the sender I get 8.2 volts on the good gauge and 8.4 on the bad one. Im willing to say this is close enough to equal given the differnent lenght circuits and voltage drop. I then removed the good sender and measured roughly 1 volt when in the empty position and 5.4 when full. I also measured ohms but am not sure I trust my old fluke 75 100%. I got 22-25 ohms on empty and 140-150 on full. Again this was on the good sender which I removed from the tank disconnected the wires from and manually actuated the float from empty to full positions. I think I need to find this type sender. On top of this VDO sender are the following numbers
I did not remove the bad sender because Im pretty sure its just the wrong type of sender and I ran out of beer
With the wires disconected from this sender im seeing 66-77 ohms when I know the tank is full. Im also seeing 3.2volts with the wires connected. Again Im not sure I trust the accuracy of my meter and admit Im not so great at using it when measuring resistance. Also of note when ever I disconnect the wires from the sender my gauge on both the good and bad tanks pegs full. If I connect the two wires together the gauge pegs empty.
Did I just get a bad sending unit or is there some funky european sender with variable voltage like Arno mentioned a few posts back? If so where do I find one of those? I suppose there is the possibility that the float on the sender I replaced is getting stuck on something inside the tank and in fact is okay. The gauge when it is connected stays right about 1/2 full which for a european gauge could be about 66-77 ohms. I guess I better get more beer
and pull the sender. But I was pretty carefull when I set it up and installed.
Boy will I feel stupid if it turns out the sender is jsut catching somthing inside the tank...