Please help,
We got an old boat with an electric gas gauge,that shows fuel when the key is off,but start it up and gauge drops to empty,stop the thing and the gauge shows gas again!
please help me fix this thing,it drives me nuts!
thanks Russ&Irene

It appears the sender unit is not matched with the guage. Possibly the sweep of of the sender will be opposite ( resistance high when full and low when empty )...but it may be as simple as the power to the guage is being picked off the wrong source ( the ignition switch may not be supplying +ve battery when it set to start )...as a temporary check, move the +ve side of the guage to a definite battery point, then the -ve side to ground ( preferably via a 20 ohm resistor, but if you just touch it for a short time it will do no harm without one)Just enough time to see if the guage comes off empty. If it does come up, then you know the guage is OK and it requires a sender that is low resistant at full, and high at empty.....with the above testing you should be able to eliminate possibilities and come up with the cause.



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see ya
Pep

I would check for a bad ground before I did anything else.
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Digger
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DSRA Member

I threw it away yesterday, now I have to go buy one
Just when you think you have won the Rat Race along come faster rats

Why not just put a meter on the gauge and check the resistence and if that is ok check to see if the power to the gauge is hooked up to the correctly. Sounds like some where down the wiring it got mixed up. Chuck