fuel gauge problem

[le3]

A week and a half ago I had the boat dropped and ran her back to my slip. On the ride back we left a farely rough inlet and I noticed the fuel guage was below E (I know it was working before because I remember commenting to my buddy about it before we got to the inlet). At first I thought that it was just the guage or the sender. I went down to the cockpit and lifted the rear hatch and noticed the bilge was not working.

So to make a long story short, something (I assume the fuel gauge) tripped the primary breaker. Once I reset the breaker back at the dock, the fuel gauge still is not working (the bidge is working now). I come to find out that my winter storage marina replaced one of the ignitions (apparently they lost the key) without telling me (wasn't really paying attention to the keys in the ignition when I first started the boat).

On top of installing the new ignition they actually installed a new genset over the winter. Any dea how a fuel guage could trip a main breaker? I am thinking that the work they did behind the dash when installing the ingition has something to do with it. Any ideas?

[Dave Kosh R.I.P.]

le3,
I would first tell them what you have and see if they will cover it under warranty. If not you just have to trace the wiring. It is pretty simple. 12 Volts to gauge and sender only when the ignition is on or in the run position. Sender fuel stick wiper wire to gauge and sender and gauge have a ground. Also to the gauge there is 12 volts positive and negative to the light when you have your instrument lighting turned on. See if they did something and be adamant about them fixing it. It sure sounds like they made the error from what you have said. Dave K

[In Memory of Vicroy]

Well, let's apply logic to the problem. A fuel gague works by passing a small amp 12v DC current thru the sender unit, which is nothing but a variable resistor (some call it a reostat) that makes more reisstance (ohms) when the tank is full and less when the tank is empty. Most use a float to move the variable resistor thru a lever. The gague on the dash is nothing more than a sensitive voltmeter that reads the voltage coming thru the variable resistor sender - more volts reads full, less reads empty. Because the voltage differential is so small, any added resistance in the circuit (corroded terminals, wires broke) will cause it to read wrong or not at all. In most cases the initial 12V DC comes from one of your ignition switches (turn it on and the voltage goes downstream), then is fed thru wiring to one terminal on the fuel tank sender, and out the other side (after being "resisted" or knocked down some by the sender) back to the fuel gague, which reads the voltage that comes back to it. All DC circuits must have two sides, the + (goes thru the sender) and a minus (ground) to measure the + against. The ground to make the gague read the minute changes in voltage is on the "other side" of the the gague. The ground is just as important as the plus side. Think this thru and you will find the problem, probably a faulty + out of the new ignition switch or a bad ground at the gague when the voltage comes back. Since we are talking about so little current (amps, or micro amps) in this kind of circuit, any little fault in either the positive thru the sender or on the ground side will cause havoc.

UV

[In Memory Walter K]

They installed a new Genset without asking you? Have you gotten their bill yet? Walter

[le3]

I am actually a little put off that they changed the ignition without asking me. Yes I paid the bill already for the genset.