How to reconnect fuel gauge wires?

[capestriper]

Hi all,

As usual, thanks in advance for any advice!

I've read a bunch of related posts, but still stuck on how to repair my non-functioning fuel gauge in my 2000 Osprey 200.  As you can see from the attached pictures. the screw head corroded off the wiring, leaving the pink (sending i believe) attached, but the black (ground?) with nowhere to attach.  The fuel gauge is pegged empty in this state.  When I hold the black wire to the top of the screw (above the nut over the pink wire), it bounces to full.  Additionally, when I hook up mutlimeter (one against the screw head and one on the black wire) i get a reading of 144 ohms (the tank was full during this testing.) i thought I had read elsewhere that is should read 244 when full?

Is there a solution (temp or otherwise) to get me through this summer?  Is the correct position for the black wire to be attached at the top of the screw? 

I'll be on my boat this weekend so can try/test any solutions you all have.

Thanks again!

[Blue Agave]

Easy fix, buy a new sender.

[Capt. Bob]

Agreed.

Is there a tank bonding lug you can see? That's where the green wire (and the black) should be. Chances are the rheostat in the sending unit is shot to hell (hence the peg to full) when you ground the black wire.

So now you have three choices.
New gauge
Tank empty (stays empty)
Tank full (stays full)

Assuming you get the screws out and replace the sender, you can use one of the screws as a ground if no bonding lug is available.

Here's a popular model many of us have.
http://www.wemausa.com/sensors/level-FuelWater.shtml#.V4kO7BJvCvY

Good luck.

[capestriper]

Thank you for the replies. 

So am i to understand correctly that the black/green should not be attached to anything on the rusted sending unit top, but instead it should be connect to eleswhere on the fuel tank.  If i recall, when i first got in there, there was a screw head 'attached' to the back/green ring connector.  i had assumed that it had snapped off the center bolt above the nut holding the pink wire on, but perhaps i missed the real connection for the black.

thanks.

[Capt. Bob]

You need to have the sender grounded. Some brands have a lug (or screw) on the gauge itself (probably what you had). Others have two wires coming from the gauge itself (as in the link supplied) That gauge would be wired by splicing the pink that is currently attached to your existing gauge to the pink (or possibility white) coming from the new gauge. Black splices to black but you must confirm that the existing black wire has a good ground at the other end. The green is the tank bond that is carried between the fill, the tank and your ground. I would think that the black should terminate at your ground buss (or the back of the gauge which is also wired to the ground buss). The green probably terminates at your fill.

When you touched the black to the mounting screw, you completed the grounding of the gauge so...

Depending on the course you take, replacement of the sender will eventually be needed for your gauge to function correctly. Depending on the brand you pick, you may get a unit with two wires (strongly suggested) or just a "naked" sender. That style will have the center post for your pink wire and a dedicated lug on the sender face for your black and green wire.

Two wire WEMA sender. Note tank lug for bond (green wires). Sender ground is run back to the ground buss at the helm in this pic.




Good luck.

[capestriper]

Thanks Capt Bob!  It looks to me the old ground connection was the 2 oclock position on the unit plate, in between the mounting screws at 12:30 and 3pm.  In the short term, what if i were to remove one of the mounting bolts and hook the ground that way?

[Capt. Bob]

That will work but if the sender is shot, it's just going to read full (pegged) all the time.

Good luck.

[capestriper]

Thanks again.  I wanted to reply for posterity sake (and anyone else who might stumble across this issue/thread) that reattaching the ground to one of the mounting screws worked for me, even on this old rusted sending unit.

[love2fish]

glad that fixed your problem.

not to be the bearer of bad news- but you may want to pull that gas tank sooner than later and give it a thorough inspection for pit marks and holes, based on the condition of that sending unit- looks like there has been a good amount of trapped moisture in there. hopefully it's just the sending unit- but mine looked brand new on the top when I re-cored the coffin lid, but the sides had some pretty good sized holes and eventually gave way to a good leak.