Guys, I recently replaced the bow mounted tank in my '76 18 OB with a new Moeller unit of the same dimensions as the original. This boat was originally rigged so you must turn on the running lights to activate the fuel gauge(?)...whatever.... I plugged in the Moeller sender like the old one (sender pre-installed in the new tank), but with the tank is 1/3 full for testing the fuel gauge "pegs E" when I turn on the lights. The original gauge has 4 posts like the other fuel gauge wiring diagrams I have seen online: input from sender, ground, hot, and a light. There does not seem to be much to go wrong with this system - other than user error. Would my 1976 gauge NOT be compatible with a 2013 sender for some reason? I thought I should post here before buying a new gauge.... Thanks! Scott [vicariously boating every weekend through this great website - keep the posts coming]
Yes, not compatible. Make sure the new one is compatible with your sender. The gauge and sender should get power from the ignition switch, not the light switch. jim
I think the standard sending unit is 33-240 ohms which is what is in the Moeller. Jim is correct in that you need a new gauge - luckily they are not expensive.
New tank with modern sending unit = need for new gauge. Do not wire the gauge thru the light switch. There is a purple wire (if you have a Merc) that comes out of the shift/throttle box that is 12 VDC and is ignition key controlled. Use that wire for all gauges and accessories. If you have something that draws alot of electricity such as a trolling motor or stereo use a separate lead to the battery. You should not have to turn on the lights to use the fuel gauge or any thing else. It sounds like a backyard electrician found some power and fed it to the fuel gauge.
