fuel gauge issue

I was replacing the fuel gauge in my boat today and incorrectly wire the gauge. I turned on the ignition switch before I discovered that I had wired in wrong. I put the ignition wire on the sender post and the sender on the ignition post. The gauge of course didn't work. I reversed the wires and tried again and it still didn't work. Did I fry the gauge. I am assuming that I probably did, but want some verification before I order another gauge.

Re: fuel gauge issue

denpat said:

I was replacing the fuel gauge in my boat today and incorrectly wire the gauge. I turned on the ignition switch before I discovered that I had wired in wrong. I put the ignition wire on the sender post and the sender on the ignition post. The gauge of course didn't work. I reversed the wires and tried again and it still didn't work. Did I fry the gauge. I am assuming that I probably did, but want some verification before I order another gauge.

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No, I'm afraid you fried the sender...

When you get a new fuel gauge, the sender post has a little tag on it that says, "Do not attach 12V+ to the sender post. Doing so will cause irrepairable damage to the sending unit."

Re: fuel gauge issue

I don't think you fried the sender. Here is how it should be.

http://www.moellermarine.com/sites/moellermarine/files/gauge_sender_wiring_diagram.jpg

Normal resistance of the sender is 33 to 240 ohms.

Re: fuel gauge issue

I just got back in from running some more tests. I found out that the purple wire that goes to the ignition, for what ever reason, was not hot. I pull power off the tachometer and the gauge moved a little. The tank is completely empty. I put a jumper on the sender and the gauge went way past full. It looks like I just got lucky and didn't burn out anything. A blind squirrel finds a nut sometimes. Thanks for responding.

Re: fuel gauge issue

Glad to see my fuel gauge diagram has made it to a commercial web site. Guess I should copyright them. Are you sure the gauge was the problem to begin with? Most of the time it is not.

Re: fuel gauge issue

denpat said:

I just got back in from running some more tests. I found out that the purple wire that goes to the ignition, for what ever reason, was not hot. I pull power off the tachometer and the gauge moved a little. The tank is completely empty. I put a jumper on the sender and the gauge went way past full. It looks like I just got lucky and didn't burn out anything. A blind squirrel finds a nut sometimes. Thanks for responding.

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You got lucky. Had the purple wire been hot, that sender would have been toast...

Re: fuel gauge issue

There wasn't anything seriously wrong with the old gauge I just thought a new one would look better. After I posted that the purple wire wasn't hot I asked my self why not. I went back out and did some more diagnostics on the electrical and found that the purple wire went to the accessory switch and that switch had to be on before it was hot. I felt better when I found that, because I wouldn't have ever put power to the gauge possibly frying the sending unit. I had previously replaced the sending unit and didn' want to go through that drill again. Still don't know why it would be wired through the accessory switch, but its an older boat and who knows what someone has done to the wiring.