fuel gauge?

ANY OF THE BOAT STORES, DO A SEARCH ON THIS SITE BECAUSE THERE HAVE BEEN SEVERAL THREADS ON THE PROS AND CONS OF A FUEL GAUGE ALONG WITH WIRING TIPS AND DIAGNOSTICS.
 
maybe I got a little ahead of myself, so the gauge isn't working.

All the other gauges work fine, there are four connections and wires on the back of the gauge, the light blue wire and connection on top turns the light on for the gauge, (it works), the connection on the right with the purple wires, is hot when the power is on, the one in the center is the ground, and the connection on the left has a red wire on it.

The one on the left never lights up with the test light. I think it is the one going to the tank. I also replaced the sending unit in the fall.

So I guess my question is

"Should the wire that goes to the tank light up with the test light when the power is on, and should the test light come on at the sending unit?
 
Cy before I would touch anything with the potential for spark to anything with vroom juice I would do a search on this site, I remember The Grand Puhbah putting out a nice disertation on the subject last year while he was holding court one day ;D he had redone his and all his V's wiring.
that was in 2005 BC Before Crabby
 
Yeah, I'm a little leary on wading in on this subject cause it was a heated discussion last year. That being said here goes. You need to have a ground wire from the sending unit to the battery ground. And a second ground for corrosion. You will have a voltage signal coming from the gauge to the sending unit. Your gauge is llooking for a ground to make the needle move, the sending unit id a variable resistor, the more current that flows thru the sending uniy, the more the nedle moves.
Here is a link to a typical wiring diagram
http://i3.photobucket.com/albums/y67/Flafranco/gauge_measurements_wiringdiagram.jpg

Your wire colors may be different, But the voltage(red) wire feed the gauge, the ground (black) goes to the sending unit, thru the sending uniy and out to battery ground. The light(red/white wire) comes hot with your nav lights and the blue is the ground for the light. Hope this helps, comments welcome!!
 
thanks for the diagram Franco, exactly what i was looking for. and thanks to everyone else who threw in their two cents.

chris

i will keep you updated on the progress
 
I'm getting in a little late, but my '85 fuel guage didn't work either. I popped the cover in the deck and found the connection on the top of the tank was a gob of corrosion. Took it off to clean it up and the wire broke off the connector - it was a gob of corrosion too. I had other wiring problems, so went out and got a marine crimper and some connectors, cleaned it up and put it back together and the needle jumped to life. If somebody hasn't messed around with things, the wires probably all go to the right places and the first thing to check on a boat, especially one that's around salt water, is corrosion at the connections.

On the advice of a friend, I bought some Boeshield T-9 (it's a solventized parafin wax juice in a spray can - West Marine has it, or Google it and you can get it online). It's a little expensive (around $13/can) but it goes a long way and it really works to prevent corrosion. I use it on the milled surfaces of shop tools (table saw, etc.) trailer hitches, hand tools, battery terminals, etc. - it's good stuff.

Good luck with the problem.

Scott
 
thanks for all the advice guys, ;D i found the problem was a bad connection at the sending unit. Put a new female plug on and she jumped to life.


Thanks..
 
Spray some Boeshield T-9 on that connection and it won't give you any more trouble for a while.

Glad you got it fixed - mine works great. All I have to do now is put the head back on, reassemble the outdrive with a bunch of new parts, fix the outdrive hydraulics and I'll be fishin'.
 
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