fuel sender ground issue

[fastexas]

My '06 225 Tournament's Yamaha fuel gauge stopped working a few months ago (flashing 1 bar). Finally got around to
trouble-shooting this past week.....seems the tank ground is bad, because I can attach a wire to the sender ground at the tank, then to the battery ground and get a correct reading
(1/2 full, where I expected it to be). Also the same temporary ground wire shorted to the pink sender wire gives me a full tank reading, so the gauge is good.
Question is, how can I "fix" the tank ground without just running a wire to the battery negative permanently? . I've tried removing the ground and wire brushing the post (no luck), and nowhere else
on the metal tank can I get a good ground.
Thanks for any advice in advance.

 

[DennisG01]

There is a bigger issue here than your fuel gauge. From what you've written, if I'm reading correctly, it sounds like the bonding/grounding wire for your fuel tank has failed. THAT is the issue - the fuel sender is secondary. Metal fuel tanks MUST be grounded. Do not ground to the battery - ground to the negative bus bar or directly to the engine ground. There is no shortcut for this - the tank ground (lack of) must be fixed. Fix the primary issue and the secondary one will fix itself.

To start with, locate your bus bar (you may have more than one) and remove/inspect/clean/tighten every wire on there. Now check to see if you have a path to ground (bus bar) using your DMM set to resistance - checking between ring connector at the tank and bus bar. If no luck, cut off the ring connector at the tank side and peel back some of the sheathing - check again. If still no luck, then it would seem that the wire has failed somewhere in between - run a new wire.

 

[fastexas]

Thanks Dennis for this reply.
I will do this in a couple of weeks when I'm down at the dry stack again...
1) DMM...you mean my multi-meter?
2) Is the BUS bar the electrical "bar" with what looks like a bunch of ground wires (8 or 9) attached all in a row beneath all the other wiring behind the helm?
3) what ohm reading should I be looking for?
4) I assume the ring connector is how the sender ground is attached to the L-shaped bracket that is in turn attached to the fuel tank right next to the sender on top of the tank. I've already wire brushed this bracket down to shiny metal, and the sender ground wire is clean too.
5) If no luck on the resistance do you mean run a new sender tank ground wire, or a new actual tank ground? Would just grounding the sender to the BUS be adequate, and not be concerned with
the fuel tank itself being properly grounded?

 

[Halfhitch]

5) If no luck on the resistance do you mean run a new sender tank ground wire, or a new actual tank ground? Would just grounding the sender to the BUS be adequate, and not be concerned with
the fuel tank itself being properly grounded?

fastexas, Read the first paragraph that Dennis wrote above, one more time. He specifically addressed your question.

 

[DennisG01]

Thanks Dennis for this reply.
I will do this in a couple of weeks when I'm down at the dry stack again...
1) DMM...you mean my multi-meter?
2) Is the BUS bar the electrical "bar" with what looks like a bunch of ground wires (8 or 9) attached all in a row beneath all the other wiring behind the helm?
3) what ohm reading should I be looking for?
4) I assume the ring connector is how the sender ground is attached to the L-shaped bracket that is in turn attached to the fuel tank right next to the sender on top of the tank. I've already wire brushed this bracket down to shiny metal, and the sender ground wire is clean too.

1) Correct ("Digital" MM). But an analog would be fine for this application.
2) Yes.
3) Very low... in the single Ohm category. It's not an exact science, but the closer to zero (NOT infinity or "no" reading) the better.
4)Correct. But corrosion has a way of wicking up inside the vinyl sheathing of the wire. As you peel back the sheathing, you will mostly likely see the strands are black - and possibly some white/green corrosion. It's even possible that some of the strands are broken. I can't tell you how bad or good it is from where I am, nor can I tell you where the "break" is. But that's why you use the meter to at least narrow down the issue area. Then you either track the wire and repair or just replace.